Variable Interest Entities (Details Textual) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2011 LIHTC funds [Member]	Dec. 31, 2011 LIHTC funds [Member] Investments [Member]	Sep. 30, 2011 Education Loan Securitization Trusts [Member]	Dec. 31, 2011 Education Loan Securitization Trusts [Member]	Dec. 31, 2011 LIHTC investments [Member]
Variable Interest Entities (Textual) [Abstract]
Total LIHTC investments, Consolidated VIE		$ 82,000,000	$ 67,000,000		$ 2,761,000,000
Maximum exposure to Loss, Unconsolidated VIE						389,000,000
Settlement value of third party interest, approximately		30,000,000
Settlement value of third party interest, reserves		82,000,000
Cumulative effect adjustment after-tax to retained earnings	45,000,000			45,000,000
Variable Interest Entity, Carrying Amount of Assets, Unconsolidated VIE		125,000,000				993,000,000
Recapturable tax claims						93,000,000
Additional Investments in Unconsolidated LIHTC Operating Partnerships Held By Consolidated LIHTC						$ 1,100,000,000