| **Stockholders' Equity and Statutory Accounting Practices (Narrative) (Details) (USD $)In Millions, except Per Share data, unless otherwise specified** | 12 Months Ended |        | 12 Months Ended |         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|--------|-----------------|---------|
||
| Purchase price for preferred stock                                                                                                                      |            |   |            | $ 1,250 |   |   |   |
| Purchase price of surplus note of CCC                                                                                                                   |            |   |            |    |   | 1,000 |   |
| Term of CCC surplus note                                                                                                                                |            |   |            |    |   | The surplus note of CCC had a term of 30 years and accrued interest at a rate of 10% per year.  Interest on the note was payable quarterly. |   |
| Interest accrual rate for CCC surplus note                                                                                                              |            |   |            |    |   | 10.00% |   |
| Repayment on surplus note of CCC                                                                                                                        |            |   |            |    | 250 |   |   |
| Common stock dividends declared, per share                                                                                                              | $ 0.60          | $ 0.40 |       |    |   |   |   |
| Dividends per share, paid                                                                                                                               | $ 0.60          | $ 0.40 |       |    |   |   |   |
| Dividends payable without prior supervisory approval                                                                                                    | 550             |   |            |    |   |   |   |
| Syndicate 382's capital requirement                                                                                                                     |            |   |            |    |   |   | 330 |
| Capital provided by CCC                                                                                                                                 |            |   |            |    |   |   | $ 66 |

| X                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Captail provided by CCC
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| X                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Interest accrual rate for CCC surplus note
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| X                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Regulatory approval from the Illinois Department of Insurance of amount for CCC to repay of the surplus note
+ References
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| X                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Syndicate 382's capital requirement
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| X                                                                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Term of CCC surplus note
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate dividends paid during the period for each share of common stock outstanding.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate dividends declared during the period for each share of common stock outstanding.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount available as of the balance sheet date for dividend payments after computation of statutory restrictions on capital surplus.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financial instruments issued by insurance entities (surplus notes) that are includable in surplus for statutory accounting purposes as prescribed or permitted by state laws and regulations that are liabilities of the issuer.
+ References
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