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Income Taxes (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2010 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
Income Tax Contingency [Line Items] |  |  |  |
Federal income tax computed at the statutory rate |  | 35.00% | 35.00% | 35.00%
Taxable income projection, years |  | 15Y |  |
Capital losses carry forward period in years |  | 5Y |  |
Maximum taxable income projection years |  | 20Y |  |
Deferred tax assets related to unrealized losses on investments |  | $ 105 |  |
Defined testing period for ownership change, approximate years |  | 3Y |  |
Gross deferred tax asset |  | 1,700 |  |
Cumulative amounts of untaxed earnings |  | 15 | 3 | 57
Taxable income for that carryback year, limit |  | 50.00% |  |
Tax refund with respect to its carryback in the amount | 391 |  | 41 |
Benefit/provision interest and penalties related to uncertainty |  | 1.5 | 0.6 | 0.5
Impact on effective tax rate from unrecognized tax benefit |  | 47 | 25 | 9
Unrealized tax benefit |  | (935) | (221) | 1,091
Capital loss carryforwards |  | 155 |  |
NOL carryforwards |  | 943 |  |
Minimum tax credit carryforward |  | 22 |  |
Estimated tax liiability on disposition of foreign subsidiary |  | 5 |  |
Non Variable Interest Entities [Member] |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |
Valuation allowance |  | 236 | 376 |
Valuation allowance decrease |  | 140 | 376 |
Gross deferred tax asset |  | 2,582 | 2,490 |
Maximum [Member] |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |
Unrealized tax benefit |  | 25 |  |
Minimum [Member] |  |  |  |
Income Tax Contingency [Line Items] |  |  |  |
Unrealized tax benefit |  | $ 20 |  |

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