Commitments and Contingencies (Details) $ in Thousands	Mar. 31, 2019 USD ($) Advances	Dec. 31, 2018 USD ($)
Guarantor Obligations [Line Items]
FDIC shared-loss payable	$ 107,256	$ 105,618
Number Of Federal Home Loan Bank Advances | Advances
Standby Letters of Credit
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 152,862	147,333
Commitments to Extend Credit
Guarantor Obligations [Line Items]
Unused Commitments to Extend Credit	10,187,550	10,054,712
Qualified Affordable Housing Project Investments, Commitment	91,719	96,467
Qualified Affordable Housing Project Investments	$ 72,002	$ 67,952