Quarterly Financial Data (unaudited) - Schedule of Quarterly Financial Data (Detail) - 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
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 25,623	$ 25,585	$ 25,513	$ 24,738	$ 18,995	$ 19,219	$ 18,725	$ 18,946	$ 101,459	$ 75,885	$ 77,579
Interest expense	2,278	2,220	2,133	1,434	1,039	978	981	998	8,065	3,996	5,117
Net interest income	23,345	23,365	23,380	23,304	17,956	18,241	17,744	17,948	93,394	71,889	72,462
Provision for loan and lease losses	917	670	1,141	1,074	648	233	1,251	1,475	3,802	3,607	11,228
Net interest income after provision for loan and lease losses	22,428	22,695	22,239	22,230	17,308	18,008	16,493	16,473	89,592	68,282	61,234
Noninterest income	13,312	12,855	13,351	13,431	12,076	12,510	11,924	12,141	52,949	48,651	46,784
Total noninterest expense	26,029	25,243	26,832	27,411	22,562	22,019	21,790	20,883	105,515	87,254	81,133
Income before income taxes	9,711	10,307	8,758	8,250	6,822	8,499	6,627	7,731	37,026	29,679	26,885
Income taxes	2,553	2,779	2,292	2,134	1,632	2,264	1,547	2,005	9,758	7,448	5,696
Net income	$ 7,158	$ 7,528	$ 6,466	$ 6,116	$ 5,190	$ 6,235	$ 5,080	$ 5,726	$ 27,268	$ 22,231	$ 21,189
Net income per share:
Basic (in dollars per share)	$ 0.37	$ 0.39	$ 0.33	$ 0.31	$ 0.32	$ 0.38	$ 0.31	$ 0.35	$ 1.39	$ 1.37	$ 1.28
Diluted (in dollars per share)	0.37	0.39	0.33	0.31	0.32	0.38	0.31	0.35	1.39	1.37	1.28
Dividends per share	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.80	$ 0.80	$ 0.80