Nature of Operations and Summary of Significant Accounting Policies - Summary of Computation of Basic and Diluted Earnings Per Share (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
Basic earnings per share
Net income	$ 6,175	$ 4,288	$ 4,728	$ 5,358	$ 4,948	$ 4,958	$ 4,778	$ 3,417	$ 20,549	$ 18,101	$ 19,876
Less: Preferred stock dividends									125	133	370
Net income available to common shareholders	$ 6,144	$ 4,257	$ 4,697	$ 5,327	$ 4,917	$ 4,918	$ 4,747	$ 3,386	$ 20,424	$ 17,968	$ 19,506
Weighted average common shares outstanding	11,937,247	11,605,976	9,240,005	9,216,011	9,212,156	9,208,707	9,182,986	8,630,966	10,510,296	9,060,702	8,619,330
Basic Earnings Per Share	$ 0.51	$ 0.37	$ 0.51	$ 0.58	$ 0.53	$ 0.53	$ 0.52	$ 0.39	$ 1.94	$ 1.98	$ 2.26
Diluted earnings per share
Net income available to common shareholders									$ 20,424	$ 17,968	$ 19,506
Weighted average common shares outstanding	11,937,247	11,605,976	9,240,005	9,216,011	9,212,156	9,208,707	9,182,986	8,630,966	10,510,296	9,060,702	8,619,330
Effect of dilutive securities:
Warrants									220,316	315,679	303,970
Weighted average shares outstanding	12,013,743	11,893,254	9,637,586	9,609,506	9,628,240	9,588,332	9,560,939	9,021,786	10,798,208	9,454,125	9,000,963
Diluted Earnings Per Share	$ 0.51	$ 0.36	$ 0.49	$ 0.55	$ 0.51	$ 0.51	$ 0.50	$ 0.38	$ 1.89	$ 1.90	$ 2.17
Restricted Stock [Member]
Effect of dilutive securities:
Effect of dilutive securities									32,010	39,476	40,160
Stock Options [Member]
Effect of dilutive securities:
Effect of dilutive securities									35,586	38,268	37,503