Loans and Allowance for Credit Losses Activity in the Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 204,917	$ 225,439
Loans charged off	(10,268)	(22,106)
Recoveries of loans previously charged off	1,857	3,194
Net loans charged off	(8,411)	(18,912)
Provision for credit losses	2,500	15,000
Balance at end of period	$ 199,006	$ 221,527