Derivative Instruments and Balance Sheet Offsetting (Net Gains (Losses) Related to Changes in Fair Value) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (83)	$ 61	$ (110)
Forward contracts related to mortgage loans to be delivered for sale | Mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	692	193	(267)
Interest rate lock commitments | Mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(1,356)	(132)	157
Power Equity CD | 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	$ 581	$ 0	$ 0