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