Income Taxes (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Variable Interest Entity [Line Items]
Federal statutory rate	35.00%	35.00%
Net deferred tax asset	$ 1,600,000,000
Capital losses carryforward period in years	5 years
Taxable income projections, years	15 years
Maximum taxable income projection, years	20 years
Deferred tax assets related to net unrealized losses on investments	20,000,000
Unrealizable deferred tax assets	1,600,000,000
Capital loss carryforward		155,000,000
NOL carryforward		943,000,000
Minimum tax credit carryforward		22,000,000
Non Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Net deferred tax asset	1,635,000,000	1,745,000,000
Valuation allowance	277,000,000	236,000,000
Valuation allowance increase	$ 41,000,000