Variable Interest Entities (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
LIHTC investments [Member]
Variable Interest Entities Information
Variable Interest Entity, Carrying Amount of Assets, Unconsolidated VIE	$ 1,064,000,000
Variable Interest Entity, Carrying Amount of Liabilities, Unconsolidated VIE	0
Maximum Exposure To Loss, Unconsolidated VIE	476,000,000
Variable Interest Entities (Textuals) [Abstract]
Maximum Exposure To Loss, Unconsolidated VIE	392,000,000
Recapturable tax claims	84,000,000
Additional Investments In Unconsolidated LIHTC Operating Partnerships Held By Consolidated LIHTC	1,000,000,000
LIHTC funds [Member]
Variable Interest Entities Information
Variable Interest Entity, Carrying Amount of Assets, Consolidated VIE	91,000,000
Variable Interest Entity, Carrying Amount of Assets, Unconsolidated VIE	149,000,000
Variable Interest Entity, Carrying Amount of Liabilities, Unconsolidated VIE	0
Maximum Exposure To Loss, Unconsolidated VIE	0
Variable Interest Entities (Textuals) [Abstract]
Settlement value of third party interest, Consolidated VIE, minimum	42,000,000
Settlement value of third party interest, Consolidated VIE, maximum	47,000,000
Settlement value of third party interest, reserves	100,000,000
LIHTC funds [Member] | Investments [Member]
Variable Interest Entities Information
Variable Interest Entity, Carrying Amount of Assets, Consolidated VIE	75,000,000
Education Loan Securitization Trusts [Member]
Variable Interest Entities Information
Variable Interest Entity, Carrying Amount of Assets, Consolidated VIE	3,134,000,000
Variable Interest Entity, Carrying Amount of Liabilities, Consolidated VIE	$ 2,949,000,000