Loans and Allowance for Credit Losses Activity in the Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 237,316	$ 268,633	$ 258,177	$ 275,498
Loans charged off	(29,966)	(32,897)	(110,765)	(119,101)
Recoveries of loans previously charged off	4,918	2,081	11,356	7,420
Net loans charged off	(25,048)	(30,816)	(99,409)	(111,681)
Provision for credit losses	23,000	31,000	76,500	105,000
Balance at end of period	$ 235,268	$ 268,817	$ 235,268	$ 268,817