Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Data
Interest income	$ 32,779	$ 32,308	$ 31,500	$ 31,195	$ 31,081	$ 30,177	$ 30,044	$ 29,964	$ 127,782	$ 121,266	$ 114,317
Interest expense	2,891	2,907	2,967	2,966	2,845	2,810	1,972	1,963	11,731	9,590	8,429
Net interest income	29,888	29,401	28,533	28,229	28,236	27,367	28,072	28,001	116,051	111,676	105,888
Income before income taxes	11,825	13,812	11,729	9,715	5,114	9,291	10,596	10,745	47,081	35,746	43,816
Net income from continuing operations	8,733	10,269	8,532	7,365	4,400	6,954	7,383	7,403	34,899	26,140	28,798
Income (loss) from discontinued operations, net of tax								(71)		(71)	209
Net income (loss)	$ 8,733	$ 10,269	$ 8,532	$ 7,365	$ 4,400	$ 6,954	$ 7,383	$ 7,332	$ 34,899	$ 26,069	$ 29,007
Basic	$ 0.21	$ 0.25	$ 0.21	$ 0.18	$ 0.11	$ 0.17	$ 0.17	$ 0.18	$ 0.84	$ 0.63	$ 0.70
Diluted	$ 0.21	$ 0.25	$ 0.21	$ 0.18	$ 0.11	$ 0.17	$ 0.17	$ 0.18	$ 0.84	$ 0.62	$ 0.70
Other Investments		$ 1,400							$ 2,477	$ 1,312	$ (56)
Provision for loan losses		$ 1,200			$ 5,400				$ (2,101)	$ 6,420	$ (4,155)