Credit Commitments (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Credit Commitments
Total Credit Commitments	$ 1,936,912	$ 1,997,825
Unfunded Commitments to Extend Credit
Credit Commitments
Total Credit Commitments	1,822,387	1,875,459
Standby Letters of Credit
Credit Commitments
Total Credit Commitments	90,190	97,708
Commercial Letters of Credit
Credit Commitments
Total Credit Commitments	$ 24,335	$ 24,658