Quarterly Financial Data -- Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Interest income	$ 35,788	$ 33,488	$ 30,131	$ 25,158	$ 25,313	$ 24,614	$ 25,446	$ 24,182
Interest expense	4,786	3,401	2,677	1,963	1,838	1,741	1,493	1,410	$ 12,827	$ 6,482	$ 4,292
Net interest income	31,002	30,087	27,454	23,195	23,475	22,873	23,953	22,772	111,738	93,073	71,204
Provision for loan losses	3,184	2,551	1,877	1,055	2,411	1,489	1,840	1,722
Net interest income after provision for loan losses	27,818	27,536	25,577	22,140	21,064	21,384	22,113	21,050	103,071	85,611	68,378
Other income	11,647	7,919	8,361	7,487	7,210	7,661	7,969	7,496	35,414	30,336	26,912
Other expense	26,320	24,490	20,796	18,374	19,152	17,912	17,955	19,202	89,980	74,221	61,510
Income before income taxes	13,145	10,965	13,142	11,253	9,122	11,133	12,127	9,344	48,505	41,726	33,780
Total	3,206	2,731	3,105	2,863	4,497	3,538	3,927	3,080	11,905	15,042	11,940
Net income					4,625	7,595	8,200	6,264	36,600	26,684	21,840
Dividends on preferred shares					0	0	0	0	0	0	825
Net income available to common stockholders	$ 9,939	$ 8,234	$ 10,037	$ 8,390	$ 4,625	$ 7,595	$ 8,200	$ 6,264	$ 36,600	$ 26,684	$ 21,015
Basic earnings per common share	$ 0.62	$ 0.54	$ 0.72	$ 0.66	$ 0.37	$ 0.61	$ 0.66	$ 0.50	$ 2.53	$ 2.13	$ 2.07
Diluted earnings per common share	$ 0.62	$ 0.54	$ 0.72	$ 0.66	$ 0.37	$ 0.61	$ 0.66	$ 0.50	$ 2.52	$ 2.13	$ 2.05