Derivative Instruments and Balance Sheet Offsetting - Net Gains (Losses) Related to Changes in Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative instruments
Total gain (loss) recognized in income	$ 365	$ (189)	$ 1,103	$ 53
Forward contracts related to mortgage loans to be delivered for sale | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Total gain (loss) recognized in income	1,185	43	794	25
Interest rate lock commitments | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Total gain (loss) recognized in income	(904)	(198)	(141)	843
Foreign exchange forwards | Other noninterest income
Derivative instruments
Total gain (loss) recognized in income	0	5	0	5
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Total gain (loss) recognized in income	$ 84	$ (39)	$ 450	$ (820)