Segment Reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment	Sep. 30, 2018 USD ($)
Segment Reporting
Number of operating segments | segment			4
Key metrics related to segments
Net interest income	$ 18,681	$ 18,929	$ 56,092	$ 55,971
Provision for loan losses	1,498	1,530	5,515	7,080
Noninterest income	29,580	26,258	84,638	76,608
Noninterest expense	37,327	34,336	106,102	100,414
Net income before taxes	9,436	9,321	29,113	25,085
Corporate Administration
Key metrics related to segments
Net interest income	(896)	(904)	(2,713)	(2,689)
Noninterest income	547	9	2,099	77
Noninterest expense	8,885	8,318	25,960	23,685
Net income before taxes	(9,234)	(9,213)	(26,574)	(26,297)
Banking | Operating Segments
Key metrics related to segments
Net interest income	19,193	19,568	57,987	57,960
Provision for loan losses	1,498	1,521	5,515	7,071
Noninterest income	1,695	1,710	5,273	5,159
Noninterest expense	10,800	10,042	30,880	29,416
Net income before taxes	8,590	9,715	26,865	26,632
Retirement and Benefit Services | Operating Segments
Key metrics related to segments
Noninterest income	15,307	15,536	46,142	46,873
Noninterest expense	8,551	8,948	26,142	27,338
Net income before taxes	6,756	6,588	20,000	19,535
Wealth Management | Operating Segments
Key metrics related to segments
Net interest income		17		47
Noninterest income	3,896	3,685	11,385	10,948
Noninterest expense	1,835	1,709	5,936	5,702
Net income before taxes	2,061	1,993	5,449	5,293
Mortgage | Operating Segments
Key metrics related to segments
Net interest income	384	248	818	653
Provision for loan losses		9		9
Noninterest income	8,135	5,318	19,739	13,551
Noninterest expense	7,256	5,319	17,184	14,273
Net income before taxes	$ 1,263	$ 238	$ 3,373	$ (78)