Commitments and Contingencies Outstanding Commitments to Extend Credit and Letters of Credit (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Commitments to Extend Credit [Member] Reserve for Off-balance Sheet Activities [Member]	Dec. 31, 2011 Commitments to Extend Credit [Member] Reserve for Off-balance Sheet Activities [Member]	Mar. 31, 2012 Standby Letters of Credit [Member] Reserve for Off-balance Sheet Activities [Member]	Dec. 31, 2011 Standby Letters of Credit [Member] Reserve for Off-balance Sheet Activities [Member]	Mar. 31, 2012 Commercial Letters of Credit [Member] Reserve for Off-balance Sheet Activities [Member]	Dec. 31, 2011 Commercial Letters of Credit [Member] Reserve for Off-balance Sheet Activities [Member]	Mar. 31, 2012 Residential Mortgage [Member] Reserve for Off-balance Sheet Activities [Member]	Dec. 31, 2011 Residential Mortgage [Member] Reserve for Off-balance Sheet Activities [Member]
ResidentialMortgagePrincipalBalanceRepurchaseRequestReceived	$ 3,200,000	$ 2,400,000
ResidentialMortgagePrincipalBalanceFHLBCreditEnhancement	279,000,000
ResidentialMortgageRepurchaseReservesFHLBCreditEnhancement	2,600,000
Valuation allowances and Reserves, Balance			$ 3,900,856,000	$ 3,803,532,000	$ 432,225,000	$ 444,019,000	$ 28,795,000	$ 31,557,000	$ 4,000,000	$ 1,500,000