Loans - Changes in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in the Allowance for Loan Losses
Balance, beginning of year				$ 18,379				$ 19,164	$ 18,379	$ 19,164	$ 19,027
Charge-offs									(538)	(927)	(1,952)
Recoveries									1,053	480	2,905
Net (charge-offs) recoveries									515	(447)	953
Provision (credit) for loan losses	$ 371	$ (301)	$ 22	(60)	$ (106)	$ (24)	$ (198)	(10)	32	(338)	(816)
Balance, end of year	18,926				18,379				18,926	18,379	19,164
Commercial
Changes in the Allowance for Loan Losses
Balance, beginning of year				11,187				12,533	11,187	12,533	12,866
Charge-offs									(527)	(815)	(1,676)
Recoveries									877	418	2,621
Net (charge-offs) recoveries									350	(397)	945
Provision (credit) for loan losses									(789)	(949)	(1,278)
Balance, end of year	10,748				11,187				10,748	11,187	12,533
Real estate
Changes in the Allowance for Loan Losses
Balance, beginning of year				7,070				6,548	7,070	6,548	6,034
Charge-offs									(2)	(87)	(276)
Recoveries									146	62	283
Net (charge-offs) recoveries									144	(25)	7
Provision (credit) for loan losses									862	547	507
Balance, end of year	8,076				7,070				8,076	7,070	6,548
Consumer
Changes in the Allowance for Loan Losses
Balance, beginning of year				$ 122				$ 83	122	83	127
Charge-offs									(9)	(25)
Recoveries									30		1
Net (charge-offs) recoveries									21	(25)	1
Provision (credit) for loan losses									(41)	64	(45)
Balance, end of year	$ 102				$ 122				$ 102	$ 122	$ 83