Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Goodwill and other intangibles	$ 44,305		$ 44,305		$ 45,369
Total assets	2,292,678		2,292,678		2,159,069
Net interest income	19,919	$ 18,675	58,427	$ 54,579
Provision for loan losses	950	950	2,475	2,950
Service fees, security gains and other noninterest income	6,478	6,058	18,794	18,000
Noninterest expense	15,439	14,926	44,493	43,536
Amortization and depreciation expense	741	865	2,241	2,632
INCOME BEFORE INCOME TAXES	9,267	7,992	28,012	23,461
Income taxes	1,183	2,009	4,129	5,985
NET INCOME	8,084	5,983	23,883	17,476
Eliminations And Others
Segment Reporting Information [Line Items]
Goodwill and other intangibles	(822)		(822)		(822)
Total assets	4,661		4,661		3,935
Net interest income	(26)	(21)	(67)	(64)
Provision for loan losses	0	0	0	0
Service fees, security gains and other noninterest income	(89)	(34)	(214)	(182)
Noninterest expense	276	319	761	531
Amortization and depreciation expense	13	13	38	37
INCOME BEFORE INCOME TAXES	(404)	(387)	(1,080)	(814)
Income taxes	(101)	(203)	(346)	(527)
NET INCOME	(303)	(184)	(734)	(287)
Trust Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	4,256		4,256		4,426
Total assets	11,034		11,034		11,261
Net interest income	39	29	104	81
Provision for loan losses	0	0	0	0
Service fees, security gains and other noninterest income	1,862	1,638	5,484	4,895
Noninterest expense	1,208	1,154	3,640	3,619
Amortization and depreciation expense	62	69	187	208
INCOME BEFORE INCOME TAXES	631	444	1,761	1,149
Income taxes	132	156	370	402
NET INCOME	499	288	1,391	747
Bank Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	38,364		38,364		39,120
Total assets	2,273,904		2,273,904		2,140,508
Net interest income	19,906	18,667	58,390	54,562
Provision for loan losses	950	950	2,475	2,950
Service fees, security gains and other noninterest income	4,235	3,974	12,210	11,895
Noninterest expense	13,611	13,110	39,047	38,304
Amortization and depreciation expense	617	718	1,866	2,196
INCOME BEFORE INCOME TAXES	8,963	7,863	27,212	23,007
Income taxes	1,136	2,031	4,080	6,068
NET INCOME	7,827	5,832	23,132	16,939
Retirement Consulting Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	2,507		2,507		2,645
Total assets	3,079		3,079		$ 3,365
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Service fees, security gains and other noninterest income	470	480	1,314	1,392
Noninterest expense	344	343	1,045	1,082
Amortization and depreciation expense	49	65	150	191
INCOME BEFORE INCOME TAXES	77	72	119	119
Income taxes	16	25	25	42
NET INCOME	$ 61	$ 47	$ 94	$ 77