Derivative Instruments and Balance Sheet Offsetting - Net Gains (Losses) Related to Changes in Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative instruments
Net gains (losses) relating to derivative instruments	$ 15	$ (72)
Forward contracts related to mortgage loans to be delivered for sale | Mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(977)	(233)
Interest rate lock commitments | Mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	1,223	161
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (231)	$ 0