Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Goodwill and other intangibles	$ 49,617				$ 42,645				$ 49,617	$ 42,645
Total assets	3,071,148				2,449,158				3,071,148	2,449,158
Net interest income	25,803	$ 24,165	$ 23,921	$ 22,302	21,165	$ 20,757	$ 20,491	$ 19,965	96,191	82,378	$ 78,501
Provision for loan losses	3,000	2,600	2,400	1,100	600	550	750	550	9,100	2,450	3,000
Service fees, security gains and other noninterest income									37,155	28,602	25,499
Noninterest expense									70,852	62,616	59,775
Amortization and depreciation expense									3,122	2,839	2,942
INCOME BEFORE INCOME TAXES	13,708	13,312	12,917	10,335	11,861	11,225	10,031	9,958	50,272	43,075	38,283
Income tax	2,351	2,443	1,906	1,696	2,186	2,071	1,488	1,570	8,396	7,315	5,714
NET INCOME	11,357	$ 10,869	$ 11,011	$ 8,639	9,675	$ 9,154	$ 8,543	$ 8,388	41,876	35,760	32,569
Eliminations And Others
Segment Reporting Information [Line Items]
Goodwill and other intangibles	(3,558)				(822)				(3,558)	(822)
Total assets	373				4,482				373	4,482
Net interest income									(295)	(79)	(86)
Provision for loan losses									0	0	0
Service fees, security gains and other noninterest income									(381)	(264)	(330)
Noninterest expense									1,206	980	889
Amortization and depreciation expense									252	49	0
INCOME BEFORE INCOME TAXES									(2,134)	(1,372)	(1,305)
Income tax									(583)	(459)	(443)
NET INCOME									(1,551)	(913)	(862)
Trust Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	6,046				6,326				6,046	6,326
Total assets	15,147				13,892				15,147	13,892
Net interest income									125	156	141
Provision for loan losses									0	0	0
Service fees, security gains and other noninterest income									9,353	9,097	8,942
Noninterest expense									5,963	6,015	6,251
Amortization and depreciation expense									304	365	448
INCOME BEFORE INCOME TAXES									3,211	2,873	2,384
Income tax									674	604	504
NET INCOME									2,537	2,269	1,880
Bank Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	47,129				37,141				47,129	37,141
Total assets	$ 3,055,628				$ 2,430,784				3,055,628	2,430,784
Net interest income									96,361	82,301	78,446
Provision for loan losses									9,100	2,450	3,000
Service fees, security gains and other noninterest income									28,183	19,769	16,887
Noninterest expense									63,683	55,621	52,635
Amortization and depreciation expense									2,566	2,425	2,494
INCOME BEFORE INCOME TAXES									49,195	41,574	37,204
Income tax									8,305	7,170	5,653
NET INCOME									$ 40,890	$ 34,404	$ 31,551