Derivative Instruments and Balance Sheet Offsetting - Net Gains (Losses) Related to Changes in Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative instruments
Total gain (loss) recognized in income	$ 227	$ (84)	$ 242	$ (156)
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	959	(409)	(18)	(642)
Interest rate lock commitments | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Total gain (loss) recognized in income	(181)	325	1,041	486
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Total gain (loss) recognized in income	$ (551)	$ 0	$ (781)	$ 0