Commitments and Contingencies - Commitments and Letters of Credit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Commitment And Contingencies [Line Items]
Commitments and letters of credit	$ 1,594,230	$ 1,717,530
Standby Letters of Credit
Commitment And Contingencies [Line Items]
Commitments and letters of credit	84,534	97,676
Commitments to Extend Credit
Commitment And Contingencies [Line Items]
Commitments and letters of credit	$ 1,509,696	$ 1,619,854