Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Entity Information
Credit Extension Commitments	$ 1,600,034	$ 1,401,686
Credit Extension Commitments, Beyond One Year	424,542	388,752
Standby Letters of Credit
Entity Information
Credit Extension Commitments	50,613	52,250
Unused Credit Card Lines
Entity Information
Credit Extension Commitments	$ 544,922	$ 581,695