Derivative Financial Instruments - Derivatives Not Designated as Hedges (Details) - Derivatives Not Designated as Hedging Instruments - Other noninterest income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest rate swaps
Impact on pretax earnings of derivatives not designated as hedges
Net Gains (Losses) on Derivatives	$ 819	$ 901	$ 510
Funding Swap (Visa Derivative)
Impact on pretax earnings of derivatives not designated as hedges
Net Gains (Losses) on Derivatives	(169)	25
Foreign exchange contracts
Impact on pretax earnings of derivatives not designated as hedges
Net Gains (Losses) on Derivatives	$ 171	$ (240)	$ 93