Securities - Amortized Cost and Estimated Fair Value by Maturity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amortized Cost
Due in one year or less	$ 23,342
Due after one year through five years	104,876
Due after five years through ten years	105,944
Due after ten years	31,366
Amortized Cost	346,733
Fair Value
Due in one year or less	23,422
Due after one year through five years	106,028
Due after five years through ten years	104,973
Due after ten years	30,639
Fair Value	346,502
Gross realized gains and losses [Abstract]
Realized gains	844	$ 871	$ 507
Realized losses	(8)	(4)	(2)
Other-than-temporary impairment	0	$ 0	$ 0
Mortgage-backed and CMOs
Amortized Cost
Mortgage-backed and CMOs	79,917
Fair Value
Mortgage-backed and CMOs	79,492
Equity securities
Amortized Cost
Equity securities	1,288
Fair Value
Equity securities	$ 1,948