Financial Instruments with Off-Balance Sheet Risk (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Entity Information
Credit Extension Commitments	$ 1,144,695	$ 1,049,796
Credit Extension Commitments, Beyond One Year	253,130,000	283,861,000
Standby Letters of Credit
Entity Information
Credit Extension Commitments	66,702,000	69,934,000
Unused Credit Card Lines
Entity Information
Credit Extension Commitments	$ 337,532,000	$ 285,761,000