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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 217,626	$ 237,316	$ 225,439	$ 258,177
Loans charged off	(18,108)	(29,966)	(61,597)	(110,765)
Recoveries of loans previously charged off	3,820	4,918	10,996	11,356
Net loans charged off	(14,288)	(25,048)	(50,601)	(99,409)
Provision for credit losses	9,500	23,000	38,000	76,500
Balance at end of period	$ 212,838	$ 235,268	$ 212,838	$ 235,268