Derivative Instruments and Balance Sheet Offsetting (Net Gains (Losses) Related to Changes in Fair Value) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (395)	$ (76)	$ (551)	$ 15
Forward contracts related to mortgage loans to be delivered for sale [Member] | Net gain on sales of loans [Member]
Derivative instruments
Net gains (losses) relating to derivative instruments	(156)	(384)	(798)	(24)
Interest rate lock commitments [Member] | Net gain on sales of loans [Member]
Derivative instruments
Net gains (losses) relating to derivative instruments	(179)	308	307	39
Power Equity CD [Member] | Other noninterest income [Member]
Derivative instruments
Net gains (losses) relating to derivative instruments	0	0	0	0
Customer-initiated derivatives [Member] | Other noninterest income [Member]
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (60)	$ 0	$ (60)	$ 0