Commitments and Contingencies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) Advances	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Guarantor Obligations [Line Items]
Qualified Affordable Housing Project Investments	$ 107,400		$ 85,600
FDIC Indemnification Asset	5,281	$ 7,474	4,054	$ 5,808	$ 21,340	$ 28,701
FDIC loss share payable	94,252		126,453
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	$ 8,260,000		7,950,000
Qualified Affordable Housing Project Investments, Commitment	54,700		41,800
Standby Letters of Credit
Guarantor Obligations [Line Items]
Guarantor obligations amount	$ 82,300		$ 77,900
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