Summarized Quarterly Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Summarized Quarterly Information (Unaudited) [Abstract]
Total interest income	$ 28,430	$ 28,178	$ 27,566	$ 24,159	$ 22,868	$ 20,566	$ 18,614	$ 18,152
Total interest expense	2,566	2,642	2,773	2,740	2,744	2,707	2,571	2,672	$ 10,721	$ 10,694	$ 11,686
Net interest income	25,864	25,536	24,793	21,419	20,124	17,859	16,043	15,480	97,612	69,506	55,385
Provision for loan losses	7,238	5,837	672	350	128	(380)	583	8
Net loss on asset disposals and other transactions	(498)	(51)	(136)	(1,103)	(146)	(109)	(187)	11	(1,788)	(431)	(155)
Net gain on securities transactions	56	62	11	600	238	124	66	(30)	729	398	489
Other income	12,101	11,906	11,926	11,508	10,178	9,861	9,719	10,295
Amortization of other intangible assets	1,133	1,127	1,144	673	516	367	282	263	4,077	1,428	807
Acquisition-related expenses	838	109	732	9,043	1,869	1,462	1,271	150
Other expense	25,306	24,876	26,902	23,198	21,596	20,378	18,451	18,404
Applicable income tax benefit	425	1,370	2,231	(151)	2,040	1,729	1,577	2,148	3,875	7,494	11,510
Net income	$ 2,583	$ 4,134	$ 4,913	$ (689)	$ 4,245	$ 4,179	$ 3,477	$ 4,783	$ 10,941	$ 16,684	$ 17,574
Earnings per common share - basic	$ 0.14	$ 0.23	$ 0.27	$ (0.04)	$ 0.29	$ 0.33	$ 0.32	$ 0.45	$ 0.62	$ 1.36	$ 1.65
Earnings per common share - diluted	$ 0.14	$ 0.22	$ 0.27	$ (0.04)	$ 0.28	$ 0.32	$ 0.32	$ 0.44	$ 0.61	$ 1.35	$ 1.63
Weighted-average number of common shares outstanding - basic	18,142,997	18,127,131	18,116,090	15,802,334	14,660,314	12,632,341	10,755,509	10,636,089	17,555,140	12,183,352	10,581,222
Weighted-average number of common shares outstanding - diluted	18,278,272	18,271,979	18,253,918	15,930,235	14,809,289	12,765,880	10,880,090	10,740,884	17,687,795	12,306,224	10,679,417