Financial Instruments with Off-Balance Sheet Risk (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Entity Information [Line Items]
Credit Extension Commitments	$ 1,596,930
Credit Extension Commitments, Beyond One Year	416,411
Standby Letters of Credit
Entity Information [Line Items]
Credit Extension Commitments	50,022
Unused Credit Card Lines
Entity Information [Line Items]
Credit Extension Commitments	$ 550,354