Derivative Instruments and Balance Sheet Offsetting (Net Gains (Losses) Related to Changes in Fair Value) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (1,079)	$ (1,431)	$ (83)
Forward contracts related to mortgage loans to be delivered for sale | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(685)	(669)	692
Interest rate lock commitments | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(173)	266	(1,356)
Power Equity CD | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	0	0	0
Foreign exchange forwards | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	0	0	0
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (221)	$ (1,028)	$ 581