Commitments and Contingencies (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended							3 Months Ended
	Feb. 28, 2011	Mar. 31, 2012 Commitments to Extend Credit [Member]	Dec. 31, 2011 Commitments to Extend Credit [Member]	Mar. 31, 2011 Commitments to Extend Credit [Member]	Mar. 31, 2012 Standby Letters of Credit [Member]	Dec. 31, 2011 Standby Letters of Credit [Member]	Mar. 31, 2011 Standby Letters of Credit [Member]	Mar. 31, 2012 Recourse Obligation on Mortgage Loans Sold [Member]	Dec. 31, 2011 Recourse Obligation on Mortgage Loans Sold [Member]	Mar. 31, 2011 Recourse Obligation on Mortgage Loans Sold [Member]	Mar. 31, 2012 Obligation to Repurchase Receivables Sold [Member] Recourse Obligation on Mortgage Loans Sold [Member]
Guarantor Obligations [Line Items]
Unused commitments		$ 5,748,952	$ 5,636,942	$ 5,704,757
Guarantor obligations amount					$ 59,798	$ 57,446	$ 71,942	$ 210,789	$ 207,963	$ 191,606	$ 161,937
General maximum recourse period, days								120 days
Number of Directors in Complaint	5