Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands													3 Months Ended								12 Months Ended
	Oct. 23, 2019	Jul. 24, 2019	Apr. 24, 2019	Jan. 23, 2019	Oct. 24, 2018	Jul. 24, 2018	Apr. 25, 2018	Jan. 24, 2018	Oct. 25, 2017	Jul. 25, 2017	Apr. 25, 2017	Jan. 25, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Interest income													$ 53,943	$ 54,884	$ 55,216	$ 53,807	$ 54,884	$ 54,606	$ 46,669	$ 43,247	$ 217,850	$ 199,406	$ 147,709
Interest expense													4,828	4,641	4,680	4,019	3,595	3,480	2,928	2,410	18,168	12,413	8,346
Net interest income													49,115	50,243	50,536	49,788	51,289	51,126	43,741	40,837	199,682	186,993	139,363
Provision for loan losses													1,558	466	1,367	920	1,162	1,065	1,750	1,152	4,311	5,129	4,220
Net interest income after provision for loan losses													47,557	49,777	49,169	48,868	50,127	50,061	41,991	39,685	195,371	181,864	135,143
Noninterest income													9,011	8,458	7,564	7,429	8,445	8,050	7,575	7,548	32,462	31,618	35,579
Noninterest expense													35,997	36,719	37,547	36,525	37,273	39,461	35,706	36,747	146,788	149,187	110,575
Income before income taxes													20,571	21,516	19,186	19,772	21,299	18,650	13,860	10,486	81,045	64,295	60,147
Income tax expense													3,445	3,621	3,202	3,220	4,690	3,146	2,003	1,399	13,488	11,238	18,356
Net income													$ 17,126	$ 17,895	$ 15,984	$ 16,552	$ 16,609	$ 15,504	$ 11,857	$ 9,087	$ 67,557	$ 53,057	$ 41,791
Basic earnings per common share (in usd per share)													$ 0.47	$ 0.49	$ 0.43	$ 0.45	$ 0.45	$ 0.42	$ 0.35	$ 0.27	$ 1.84	$ 1.49	$ 1.39
Diluted earnings per common share (in usd per share)													0.47	0.48	0.43	0.45	0.45	0.42	0.35	0.27	1.83	1.49	1.39
Cash dividends declared on common stock (in usd per share)	$ 0.19	$ 0.19	$ 0.18	$ 0.18	$ 0.17	$ 0.15	$ 0.15	$ 0.15	$ 0.13	$ 0.13	$ 0.13	$ 0.12	$ 0.29	$ 0.19	$ 0.18	$ 0.18	$ 0.27	$ 0.15	$ 0.15	$ 0.15	$ 0.84	$ 0.72	$ 0.61