Commitments and Contingencies (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) Advances	Dec. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Guarantor Obligations [Line Items]
Qualified Affordable Housing Project Investments	$ 116,700	$ 109,800
FDIC shared-loss receivable	3,981	4,172	$ 7,474	$ 4,054
FDIC shared-loss payable	98,013	97,008
Federal Home Loan Bank, Advances, Maturities Summary, Fixed Rate	$ 200,000
Number Of Federal Home Loan Bank Advances | Advances	2
Commitments to Extend Credit
Guarantor Obligations [Line Items]
Unused Commitments to Extend Credit	$ 9,030,000	8,810,000
Qualified Affordable Housing Project Investments, Commitment	61,900	57,100
Standby Letters of Credit
Guarantor Obligations [Line Items]
Guarantor obligations amount	$ 80,300	$ 83,800
Recourse Obligation on Mortgage Loans Sold
Guarantor Obligations [Line Items]
Recourse Period, Maximum1	180 days
Obligation to Repurchase Receivables Sold
Guarantor Obligations [Line Items]
Reserve for estimated losses arising from repurchase of loans	$ 3,000
Each Individual Advance
Guarantor Obligations [Line Items]
Federal Home Loan Bank, Advances, Maturities Summary, Fixed Rate	$ 100,000