Variable Interest Entities (Details Textual) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended	3 Months Ended			3 Months Ended
	Sep. 30, 2011 Retained Earnings [Member]	Sep. 30, 2011 Retained Earnings [Member]	Dec. 31, 2010 Retained Earnings [Member]	Mar. 31, 2012 LIHTC funds [Member]	Mar. 31, 2012 LIHTC funds [Member] Minimum [Member]	Mar. 31, 2012 LIHTC funds [Member] Maximum [Member]	Mar. 31, 2012 LIHTC funds [Member] Investments [Member]	Mar. 31, 2012 Education Loan Securitization Trusts [Member]	Mar. 31, 2012 LIHTC investments [Member]
Variable Interest Entities (Textual) [Abstract]
Loan securitization trust VIEs				$ 87,000,000			$ 55,000,000	$ 2,747,000,000
Maximum exposure to Loss, Unconsolidated VIE									385,000,000
Settlement value of third party interest, approximately					14,000,000	26,000,000
Settlement value of third party interest, reserves				78,000,000
Cumulative effect adjustment to beginning balance of Retained Earnings	45,000,000	45,000,000	45,000,000
Variable Interest Entity, Carrying Amount of Assets, Unconsolidated VIE				124,000,000					1,035,000,000
Recapture tax claims									105,000,000
Additional Investments in Unconsolidated LIHTC Operating Partnerships Held By Consolidated LIHTC									$ 1,100,000,000