Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Goodwill and other intangibles	$ 45,755		$ 45,755		$ 45,154
Total assets	2,162,025		2,162,025		1,966,113
Net interest income	18,675	$ 17,193	54,579	$ 50,829
Provision for loan losses	950	1,110	2,950	2,880	0
Service fees, security gains and other noninterest income	6,058	6,485	18,000	17,168
Noninterest expense	14,926	14,377	43,536	42,093
Amortization and depreciation expense	865	848	2,632	2,359
INCOME BEFORE INCOME TAXES	7,992	7,343	23,461	20,665
Income taxes	2,009	1,967	5,985	5,471
NET INCOME	5,983	5,376	17,476	15,194
Eliminations And Others
Segment Reporting Information [Line Items]
Goodwill and other intangibles	(822)		(822)		(646)
Total assets	2,934		2,934		2,805
Net interest income	(21)	(21)	(64)	(69)
Provision for loan losses	0	0	0	0
Service fees, security gains and other noninterest income	(34)	(70)	(182)	(229)
Noninterest expense	319	267	531	1,256
Amortization and depreciation expense	13	16	37	17
INCOME BEFORE INCOME TAXES	(387)	(374)	(814)	(1,571)
Income taxes	(203)	(169)	(527)	(529)
NET INCOME	(184)	(205)	(287)	(1,042)
Trust Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	4,490		4,490		4,681
Total assets	11,031		11,031		10,980
Net interest income	29	27	81	69
Provision for loan losses	0	0	0	0
Service fees, security gains and other noninterest income	1,638	1,718	4,895	4,831
Noninterest expense	1,154	1,152	3,619	3,465
Amortization and depreciation expense	69	76	208	228
INCOME BEFORE INCOME TAXES	444	517	1,149	1,207
Income taxes	156	188	402	423
NET INCOME	288	329	747	784
Bank Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	39,382		39,382		38,235
Total assets	2,144,827		2,144,827		1,948,800
Net interest income	18,667	17,187	54,562	50,829
Provision for loan losses	950	1,110	2,950	2,880
Service fees, security gains and other noninterest income	3,974	4,276	11,895	11,020
Noninterest expense	13,110	12,622	38,304	36,312
Amortization and depreciation expense	718	666	2,196	1,845
INCOME BEFORE INCOME TAXES	7,863	7,065	23,007	20,812
Income taxes	2,031	1,900	6,068	5,501
NET INCOME	5,832	5,165	16,939	15,311
Retirement Consulting Segment | Operating Segments
Segment Reporting Information [Line Items]
Goodwill and other intangibles	2,705		2,705		2,884
Total assets	3,233		3,233		$ 3,528
Net interest income	0	0	0	0
Provision for loan losses	0	0	0	0
Service fees, security gains and other noninterest income	480	561	1,392	1,546
Noninterest expense	343	336	1,082	1,060
Amortization and depreciation expense	65	90	191	269
INCOME BEFORE INCOME TAXES	72	135	119	217
Income taxes	25	48	42	76
NET INCOME	$ 47	$ 87	$ 77	$ 141