Derivative Instruments and Balance Sheet Offsetting - Net Gains (Losses) Related to Changes in Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative instruments
Total gain (loss) recognized in income	$ 485	$ 509
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	66	(370)
Interest rate lock commitments | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Total gain (loss) recognized in income	709	552
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Total gain (loss) recognized in income	(290)	327
Power Equity CD | Other noninterest income
Derivative instruments
Total gain (loss) recognized in income	$ 0	$ 0