| **Fair Value (Table of reconciliation for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs) (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | $ 2,340         | $ 2,651 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | 21              | 45 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (16)            | 133 |
| Purchases                                                                                                                                                                                                      | 1,436           |   |
| Sales                                                                                                                                                                                                          | (917)           |   |
| Settlements                                                                                                                                                                                                    | (474)           |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (204) |
| Transfers into Level 3                                                                                                                                                                                         | 86              | 78 |
| Transfers out of Level 3                                                                                                                                                                                       | (725)           | (363) |
| Balance, Ending, Assets                                                                                                                                                                                        | 1,751           | 2,340 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (19)            | (16) |
| Fixed maturity securities [Member]                                                                                                                                                                             |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 2,092           | 2,467 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | (13)            | 21 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (18)            | 131 |
| Purchases                                                                                                                                                                                                      | 1,330           |   |
| Sales                                                                                                                                                                                                          | (865)           |   |
| Settlements                                                                                                                                                                                                    | (400)           |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (266) |
| Transfers into Level 3                                                                                                                                                                                         | 81              | 69 |
| Transfers out of Level 3                                                                                                                                                                                       | (700)           | (330) |
| Balance, Ending, Assets                                                                                                                                                                                        | 1,507           | 2,092 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (23)            | (20) |
| Corporate and other bonds [Member]                                                                                                                                                                             |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 624             | 609 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | (11)            | 9 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (1)             | 56 |
| Purchases                                                                                                                                                                                                      | 484             |   |
| Sales                                                                                                                                                                                                          | (204)           |   |
| Settlements                                                                                                                                                                                                    | (149)           |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 45 |
| Transfers into Level 3                                                                                                                                                                                         | 79              | 60 |
| Transfers out of Level 3                                                                                                                                                                                       | (340)           | (155) |
| Balance, Ending, Assets                                                                                                                                                                                        | 482             | 624 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (12)            | (4) |
| States, municipalities and political subdivisions [Member]                                                                                                                                                     |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 266             | 756 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  |       |    |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (1)             | 15 |
| Purchases                                                                                                                                                                                                      | 3               |   |
| Sales                                                                                                                                                                                                          |       |   |
| Settlements                                                                                                                                                                                                    | (92)            |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (507) |
| Transfers into Level 3                                                                                                                                                                                         |       | 2 |
| Transfers out of Level 3                                                                                                                                                                                       | (5)             |    |
| Balance, Ending, Assets                                                                                                                                                                                        | 171             | 266 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                |       |    |
| Asset-backed Securities [Member]                                                                                                                                                                               |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 1,199           | 1,100 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | (5)             | 6 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (13)            | 58 |
| Purchases                                                                                                                                                                                                      | 843             |   |
| Sales                                                                                                                                                                                                          | (658)           |   |
| Settlements                                                                                                                                                                                                    | (159)           |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 203 |
| Transfers into Level 3                                                                                                                                                                                         | 2               | 7 |
| Transfers out of Level 3                                                                                                                                                                                       | (355)           | (175) |
| Balance, Ending, Assets                                                                                                                                                                                        | 854             | 1,199 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (11)            | (16) |
| Residential Mortgage Backed Securities [Member]                                                                                                                                                                |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 767             | 629 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | (16)            | (10) |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (11)            | 15 |
| Purchases                                                                                                                                                                                                      | 225             |   |
| Sales                                                                                                                                                                                                          | (290)           |   |
| Settlements                                                                                                                                                                                                    | (60)            |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 181 |
| Transfers into Level 3                                                                                                                                                                                         |       |    |
| Transfers out of Level 3                                                                                                                                                                                       | (163)           | (48) |
| Balance, Ending, Assets                                                                                                                                                                                        | 452             | 767 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (6)             | (13) |
| Commercial Mortgage Backed Securities [Member]                                                                                                                                                                 |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 73              | 123 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | 20              | 10 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (7)             | 13 |
| Purchases                                                                                                                                                                                                      | 81              |   |
| Sales                                                                                                                                                                                                          | (27)            |   |
| Settlements                                                                                                                                                                                                    |       |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (8) |
| Transfers into Level 3                                                                                                                                                                                         |       | 7 |
| Transfers out of Level 3                                                                                                                                                                                       | (81)            | (72) |
| Balance, Ending, Assets                                                                                                                                                                                        | 59              | 73 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                |       | (2) |
| Other asset-backed [Member]                                                                                                                                                                                    |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 359             | 348 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | (9)             | 6 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | 5               | 30 |
| Purchases                                                                                                                                                                                                      | 537             |   |
| Sales                                                                                                                                                                                                          | (341)           |   |
| Settlements                                                                                                                                                                                                    | (99)            |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 30 |
| Transfers into Level 3                                                                                                                                                                                         | 2               |    |
| Transfers out of Level 3                                                                                                                                                                                       | (111)           | (55) |
| Balance, Ending, Assets                                                                                                                                                                                        | 343             | 359 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (5)             | (1) |
| Redeemable Preferred Stock [Member]                                                                                                                                                                            |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 3               | 2 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | 3               | 6 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | (3)             | 2 |
| Purchases                                                                                                                                                                                                      |       |   |
| Sales                                                                                                                                                                                                          | (3)             |   |
| Settlements                                                                                                                                                                                                    |       |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (7) |
| Transfers into Level 3                                                                                                                                                                                         |       |    |
| Transfers out of Level 3                                                                                                                                                                                       |       |    |
| Balance, Ending, Assets                                                                                                                                                                                        |       | 3 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                |       |    |
| Equity securities [Member]                                                                                                                                                                                     |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 26              | 11 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | (2)             | (4) |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             | 2               | 1 |
| Purchases                                                                                                                                                                                                      | 66              |   |
| Sales                                                                                                                                                                                                          | (27)            |   |
| Settlements                                                                                                                                                                                                    |       |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 17 |
| Transfers into Level 3                                                                                                                                                                                         | 5               | 8 |
| Transfers out of Level 3                                                                                                                                                                                       | (3)             | (7) |
| Balance, Ending, Assets                                                                                                                                                                                        | 67              | 26 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | (3)             | (5) |
| Derivative and other financial instruments, net [Member]                                                                                                                                                       |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 25              | (11) |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | 3               | (1) |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             |       |    |
| Purchases                                                                                                                                                                                                      | 1               |   |
| Sales                                                                                                                                                                                                          | (19)            |   |
| Settlements                                                                                                                                                                                                    |       |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 37 |
| Transfers into Level 3                                                                                                                                                                                         |       |    |
| Transfers out of Level 3                                                                                                                                                                                       |       |    |
| Balance, Ending, Assets                                                                                                                                                                                        | 10              | 25 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | 2               | (1) |
| Short-term Investments [Member]                                                                                                                                                                                |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 27              |    |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  |       |    |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             |       |    |
| Purchases                                                                                                                                                                                                      | 39              |   |
| Sales                                                                                                                                                                                                          |       |   |
| Settlements                                                                                                                                                                                                    | (29)            |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 37 |
| Transfers into Level 3                                                                                                                                                                                         |       | 1 |
| Transfers out of Level 3                                                                                                                                                                                       | (10)            | (11) |
| Balance, Ending, Assets                                                                                                                                                                                        | 27              | 27 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                |       |    |
| Life settlement contracts [Member]                                                                                                                                                                             |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 129             | 130 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  | 33              | 29 |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             |       |    |
| Purchases                                                                                                                                                                                                      |       |   |
| Sales                                                                                                                                                                                                          |       |   |
| Settlements                                                                                                                                                                                                    | (45)            |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (30) |
| Transfers into Level 3                                                                                                                                                                                         |       |    |
| Transfers out of Level 3                                                                                                                                                                                       |       |    |
| Balance, Ending, Assets                                                                                                                                                                                        | 117             | 129 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                | 5               | 10 |
| Discontinued operations investments [Member]                                                                                                                                                                   |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     |            | 16 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  |            |    |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             |            | 1 |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | (2) |
| Transfers into Level 3                                                                                                                                                                                         |            |    |
| Transfers out of Level 3                                                                                                                                                                                       |            | (15) |
| Balance, Ending, Assets                                                                                                                                                                                        |            |    |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                |            |    |
| Seperate account business [Member]                                                                                                                                                                             |            |   |
| **Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]**                                                                                              |            |   |
| Balance, Beginning, Assets                                                                                                                                                                                     | 41              | 38 |
| Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)                                                                                  |       |    |
| Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)                                                                                                             |       |    |
| Purchases                                                                                                                                                                                                      |       |   |
| Sales                                                                                                                                                                                                          | (6)             |   |
| Settlements                                                                                                                                                                                                    |       |   |
| Purchases, sales, issuances and settlements                                                                                                                                                                    |            | 3 |
| Transfers into Level 3                                                                                                                                                                                         |       |    |
| Transfers out of Level 3                                                                                                                                                                                       | (12)            |    |
| Balance, Ending, Assets                                                                                                                                                                                        | 23              | 41 |
| Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)                                                                                                |       |    |

| X                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Unrealized gains (losses) Recognized in Net Income on Level 3 Assets and Liabilities Held
+ References
No definition available.
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| X                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to assets measured at fair value on a recurring basis using unobservable inputs (Level 3).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Transfers out of assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258
+ Details**Name:**us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |