Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Guarantor Obligations [Line Items]
Qualified Affordable Housing Project Investments	$ 110,000	$ 85,600
FDIC Indemnification Asset	7,474	4,054	$ 21,340	$ 28,701
FDIC loss share payable	128,243	126,453
Commitments to Extend Credit
Guarantor Obligations [Line Items]
Unused Commitments to Extend Credit	8,080,000	7,950,000
Qualified Affordable Housing Project Investments, Commitment	58,100	41,800
Standby Letters of Credit
Guarantor Obligations [Line Items]
Guarantor obligations amount	$ 80,300	$ 77,900
Recourse Obligation on Mortgage Loans Sold
Guarantor Obligations [Line Items]
Recourse Period, Maximum1	120 days
Obligation to Repurchase Receivables Sold
Guarantor Obligations [Line Items]
Reserve for estimated losses arising from repurchase of loans	$ 3,000