| **Fair Value Measurements - Recurring by FV hierarchy (Details) - USD ($) $ in Thousands**                                                                    | Jun. 30, 2018 | Dec. 31, 2017 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | $ 22,762,737  | $ 23,593,139  |
| Fixed maturities held-for-trading:                                                                                                                            | 19,519        | 21,059        |
| Short-term investments                                                                                                                                        | 294,314       | 350,266       |
| Limited partnership interests                                                                                                                                 | 63,586        | 45,540        |
| Collateral under securities lending agreements                                                                                                                | 80,013        | 0             |
| Collateral under derivative counterparty collateral agreements                                                                                                | 16,310        | 42,750        |
| Total derivative instruments                                                                                                                                  | 62,869        | 51,359        |
| Separate account assets                                                                                                                                       | 26,676,615    | 27,660,571    |
| **Liabilities**                                                                                                                                               |          |          |
| Payable under securities lending agreements                                                                                                                   | 80,013        | 0             |
| Collateral under derivative counterparty collateral agreements                                                                                                | 10,612        | 4,911         |
| Total derivative instruments                                                                                                                                  | 73,550        | 94,543        |
| Separate account liabilities                                                                                                                                  | 26,676,615    | 27,660,571    |
| Derivative instruments designated as hedges:                                                                                                                  |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 36,388        | 27,434        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 39,325        | 51,316        |
| Derivative instruments not designated as hedges:                                                                                                              |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 26,481        | 23,925        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 34,225        | 43,227        |
| Derivative instruments not designated as hedges: | Interest rate swaps                                                                                        |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 1,461         | 3,530         |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 884           | 1,628         |
| Derivative instruments not designated as hedges: | Cross-currency swaps                                                                                       |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 20,292        | 20,320        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 32,070        | 41,599        |
| Derivative instruments not designated as hedges: | Interest rate swaptions                                                                                    |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 163           | 75            |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Derivative instruments not designated as hedges: | Other forward contracts                                                                                    |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 4,565         |          |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 1,271         |          |
| U.S. government direct obligations and U.S. agencies                                                                                                          |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,356,173     | 1,871,642     |
| Obligations of U.S. states and their subdivisions                                                                                                             |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 2,003,422     | 2,090,972     |
| Corporate debt securities                                                                                                                                     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 15,438,738    | 15,706,087    |
| **Liabilities**                                                                                                                                               |          |          |
| Payable under securities lending agreements                                                                                                                   | 80,013        |          |
| Asset-backed securities                                                                                                                                       |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,653,801     | 1,717,976     |
| Residential mortgage-backed securities                                                                                                                        |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 57,825        | 64,984        |
| Commercial mortgage-backed securities                                                                                                                         |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,319,800     | 1,357,609     |
| Collateralized debt obligations                                                                                                                               |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 932,978       | 783,869       |
| Recurring basis                                                                                                                                               |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 22,762,737    | 23,593,139    |
| Fixed maturities held-for-trading:                                                                                                                            | 19,519        | 21,059        |
| Short-term investments                                                                                                                                        | 294,314       | 350,266       |
| Limited partnership interests                                                                                                                                 | 63,586        |          |
| Equity investments                                                                                                                                            | 42,575        |          |
| Collateral under securities lending agreements                                                                                                                | 80,013        |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 39,865        | 57,820        |
| Total derivative instruments                                                                                                                                  | 62,869        | 51,359        |
| Separate account assets                                                                                                                                       | 26,676,615    | 27,660,571    |
| Total assets                                                                                                                                                  | 49,935,932    | 51,734,214    |
| Separate account assets excluded                                                                                                                              | 450,000       | 400,000       |
| **Liabilities**                                                                                                                                               |          |          |
| Payable under securities lending agreements                                                                                                                   | 80,013        |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 12,696        | 5,490         |
| Total derivative instruments                                                                                                                                  | 73,550        | 94,543        |
| Embedded derivatives - GLWB                                                                                                                                   | 513           | 11,095        |
| Separate account liabilities                                                                                                                                  | 431,960       | 409,274       |
| Total liabilities                                                                                                                                             | 598,732       | 520,402       |
| Recurring basis | Derivative instruments designated as hedges: | Interest rate swaps                                                                          |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 5,917         | 7,476         |
| Recurring basis | Derivative instruments designated as hedges: | Cross-currency swaps                                                                         |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 30,471        | 19,958        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 39,325        | 51,316        |
| Recurring basis | Derivative instruments not designated as hedges: | Interest rate swaps                                                                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 1,461         | 3,530         |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 884           | 1,628         |
| Recurring basis | Derivative instruments not designated as hedges: | Cross-currency swaps                                                                     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 20,292        | 20,320        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 32,070        | 41,599        |
| Recurring basis | Derivative instruments not designated as hedges: | Interest rate swaptions                                                                  |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 163           | 75            |
| Recurring basis | Derivative instruments not designated as hedges: | Other forward contracts                                                                  |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 4,565         |          |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 1,271         |          |
| Recurring basis | U.S. government direct obligations and U.S. agencies                                                                                        |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,356,173     | 1,871,642     |
| Fixed maturities held-for-trading:                                                                                                                            | 15,481        | 16,836        |
| Recurring basis | Obligations of U.S. states and their subdivisions                                                                                           |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 2,003,422     | 2,090,972     |
| Recurring basis | Corporate debt securities                                                                                                                   |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 15,438,738    | 15,706,087    |
| Fixed maturities held-for-trading:                                                                                                                            | 3,001         | 3,156         |
| Recurring basis | Asset-backed securities                                                                                                                     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,653,801     | 1,717,976     |
| Recurring basis | Residential mortgage-backed securities                                                                                                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 57,825        | 64,984        |
| Recurring basis | Commercial mortgage-backed securities                                                                                                       |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,319,800     | 1,357,609     |
| Fixed maturities held-for-trading:                                                                                                                            | 1,037         | 1,067         |
| Recurring basis | Collateralized debt obligations                                                                                                             |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 932,978       | 783,869       |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1)                                                                              |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Short-term investments                                                                                                                                        | 260,967       | 288,302       |
| Limited partnership interests                                                                                                                                 | 0             |          |
| Equity investments                                                                                                                                            | 37,564        |          |
| Collateral under securities lending agreements                                                                                                                | 0             |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 39,865        | 57,820        |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Separate account assets                                                                                                                                       | 16,089,089    | 16,523,630    |
| Total assets                                                                                                                                                  | 16,389,921    | 16,869,752    |
| **Liabilities**                                                                                                                                               |          |          |
| Payable under securities lending agreements                                                                                                                   | 0             |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 12,696        | 5,490         |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Embedded derivatives - GLWB                                                                                                                                   | 0             | 0             |
| Separate account liabilities                                                                                                                                  | 0             | 8             |
| Total liabilities                                                                                                                                             | 12,696        | 5,498         |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Derivative instruments designated as hedges: | Interest rate swaps         |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Derivative instruments designated as hedges: | Cross-currency swaps        |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Derivative instruments not designated as hedges: | Interest rate swaps     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Derivative instruments not designated as hedges: | Cross-currency swaps    |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Derivative instruments not designated as hedges: | Interest rate swaptions |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Derivative instruments not designated as hedges: | Other forward contracts |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             |          |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             |          |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | U.S. government direct obligations and U.S. agencies                       |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Obligations of U.S. states and their subdivisions                          |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate debt securities                                                  |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Asset-backed securities                                                    |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Residential mortgage-backed securities                                     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Commercial mortgage-backed securities                                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Collateralized debt obligations                                            |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Significant other observable inputs (Level 2)                                                                                               |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 22,753,767    | 23,583,401    |
| Fixed maturities held-for-trading:                                                                                                                            | 19,519        | 21,059        |
| Short-term investments                                                                                                                                        | 33,347        | 61,964        |
| Limited partnership interests                                                                                                                                 | 0             |          |
| Equity investments                                                                                                                                            | 5,011         |          |
| Collateral under securities lending agreements                                                                                                                | 80,013        |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 0             | 0             |
| Total derivative instruments                                                                                                                                  | 62,869        | 51,359        |
| Separate account assets                                                                                                                                       | 10,137,807    | 10,736,532    |
| Total assets                                                                                                                                                  | 33,087,322    | 34,454,315    |
| **Liabilities**                                                                                                                                               |          |          |
| Payable under securities lending agreements                                                                                                                   | 80,013        |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 0             | 0             |
| Total derivative instruments                                                                                                                                  | 73,550        | 94,543        |
| Embedded derivatives - GLWB                                                                                                                                   | 0             | 0             |
| Separate account liabilities                                                                                                                                  | 431,960       | 409,266       |
| Total liabilities                                                                                                                                             | 585,523       | 503,809       |
| Recurring basis | Significant other observable inputs (Level 2) | Derivative instruments designated as hedges: | Interest rate swaps                          |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 5,917         | 7,476         |
| Recurring basis | Significant other observable inputs (Level 2) | Derivative instruments designated as hedges: | Cross-currency swaps                         |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 30,471        | 19,958        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 39,325        | 51,316        |
| Recurring basis | Significant other observable inputs (Level 2) | Derivative instruments not designated as hedges: | Interest rate swaps                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 1,461         | 3,530         |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 884           | 1,628         |
| Recurring basis | Significant other observable inputs (Level 2) | Derivative instruments not designated as hedges: | Cross-currency swaps                     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 20,292        | 20,320        |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 32,070        | 41,599        |
| Recurring basis | Significant other observable inputs (Level 2) | Derivative instruments not designated as hedges: | Interest rate swaptions                  |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 163           | 75            |
| Recurring basis | Significant other observable inputs (Level 2) | Derivative instruments not designated as hedges: | Other forward contracts                  |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 4,565         |          |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 1,271         |          |
| Recurring basis | Significant other observable inputs (Level 2) | U.S. government direct obligations and U.S. agencies                                        |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,356,173     | 1,871,642     |
| Fixed maturities held-for-trading:                                                                                                                            | 15,481        | 16,836        |
| Recurring basis | Significant other observable inputs (Level 2) | Obligations of U.S. states and their subdivisions                                           |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 2,003,422     | 2,090,972     |
| Recurring basis | Significant other observable inputs (Level 2) | Corporate debt securities                                                                   |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 15,429,768    | 15,696,349    |
| Fixed maturities held-for-trading:                                                                                                                            | 3,001         | 3,156         |
| Recurring basis | Significant other observable inputs (Level 2) | Asset-backed securities                                                                     |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,653,801     | 1,717,976     |
| Recurring basis | Significant other observable inputs (Level 2) | Residential mortgage-backed securities                                                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 57,825        | 64,984        |
| Recurring basis | Significant other observable inputs (Level 2) | Commercial mortgage-backed securities                                                       |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 1,319,800     | 1,357,609     |
| Fixed maturities held-for-trading:                                                                                                                            | 1,037         | 1,067         |
| Recurring basis | Significant other observable inputs (Level 2) | Collateralized debt obligations                                                             |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 932,978       | 783,869       |
| Recurring basis | Significant unobservable inputs (Level 3)                                                                                                   |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 8,970         | 9,738         |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Short-term investments                                                                                                                                        | 0             | 0             |
| Limited partnership interests                                                                                                                                 | 0             |          |
| Equity investments                                                                                                                                            | 0             |          |
| Collateral under securities lending agreements                                                                                                                | 0             |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 0             | 0             |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Separate account assets                                                                                                                                       | 0             | 0             |
| Total assets                                                                                                                                                  | 8,970         | 9,738         |
| **Liabilities**                                                                                                                                               |          |          |
| Payable under securities lending agreements                                                                                                                   | 0             |          |
| Collateral under derivative counterparty collateral agreements                                                                                                | 0             | 0             |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Embedded derivatives - GLWB                                                                                                                                   | 513           | 11,095        |
| Separate account liabilities                                                                                                                                  | 0             | 0             |
| Total liabilities                                                                                                                                             | 513           | 11,095        |
| Recurring basis | Significant unobservable inputs (Level 3) | Derivative instruments designated as hedges: | Interest rate swaps                              |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Derivative instruments designated as hedges: | Cross-currency swaps                             |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Derivative instruments not designated as hedges: | Interest rate swaps                          |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Derivative instruments not designated as hedges: | Cross-currency swaps                         |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Derivative instruments not designated as hedges: | Interest rate swaptions                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Derivative instruments not designated as hedges: | Other forward contracts                      |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Total derivative instruments                                                                                                                                  | 0             |          |
| **Liabilities**                                                                                                                                               |          |          |
| Total derivative instruments                                                                                                                                  | 0             |          |
| Recurring basis | Significant unobservable inputs (Level 3) | U.S. government direct obligations and U.S. agencies                                            |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Obligations of U.S. states and their subdivisions                                               |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Corporate debt securities                                                                       |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 8,970         | 9,738         |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Asset-backed securities                                                                         |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Residential mortgage-backed securities                                                          |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Commercial mortgage-backed securities                                                           |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | 0             | 0             |
| Fixed maturities held-for-trading:                                                                                                                            | 0             | 0             |
| Recurring basis | Significant unobservable inputs (Level 3) | Collateralized debt obligations                                                                 |          |          |
| **Assets**                                                                                                                                                    |          |          |
| Fixed maturities available-for-sale:                                                                                                                          | $ 0           | $ 0           |

| X                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Cash Received For Securities Loaned
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value of investment in certain entities that calculate net asset value per share. Includes, but is not limited to, by unit, membership interest, or other ownership interest. Investment includes, but is not limited to, investment in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds. Excludes measurement of net asset value as estimate of fair value.
+ References
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| - Definition
Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of debt securities categorized neither as held-to-maturity nor trading.
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of equity securities categorized neither as held-to-maturity nor as trading.
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| - Definition
The amount of cash received as security in return for loaning securities to another party.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.
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| - Definition
Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.
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| - Definition
Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as a liability.
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| - Definition
Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.
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| - Definition
Fair value of financial and nonfinancial obligations.
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| - References
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| - Definition
The fair value of the assets held by the Entity for the benefit of separate account policyholders.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of liability for variable contracts that meet specified criteria that are backed by assets held in separate accounts and carried at the fair value of those assets.
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.
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| - Definition
Amount of investments in debt securities classified as trading.
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