Business Segments - Segment Reporting (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Segments
Number of Operating Segments | segment									3
Revenues:
Interest income	$ 22,446	$ 22,703	$ 22,423	$ 22,021	$ 22,493	$ 22,678	$ 22,303	$ 21,965	$ 89,593	$ 89,439	$ 87,049
Gains on sales of loans									8,553	8,120	6,336
Other noninterest income									18,186	17,507	14,378
Total operating income									116,332	115,066	107,763
Expenses:
Provision for loan losses									16,435	18,040	15,512
Interest expense									9,601	8,968	8,694
Salaries and employee benefits									43,104	41,925	38,926
Other noninterest expenses									29,226	28,215	27,248
Total operating expenses									98,366	97,148	90,380
Income (loss) before income taxes	4,079	4,248	5,987	3,652	3,866	4,315	6,561	3,176	17,966	17,918	17,383
Income tax expense (benefit)									11,394	4,459	4,853
Net income	(3,315)	$ 3,017	$ 4,139	$ 2,731	3,082	$ 3,187	$ 4,706	$ 2,484	6,572	13,459	12,530
Total assets	1,509,056				1,451,992				1,509,056	1,451,992	1,405,076
Goodwill	14,425				14,425				14,425	14,425	14,425
Capital expenditures									4,008	3,118	1,909
Other
Revenues:
Interest income									1	2
Other noninterest income									1,905	1,273	1,579
Total operating income									1,906	1,275	1,579
Expenses:
Interest expense									1,151	1,143	1,163
Salaries and employee benefits									1,948	1,546	1,389
Other noninterest expenses									669	530	560
Total operating expenses									3,768	3,219	3,112
Income (loss) before income taxes									(1,862)	(1,944)	(1,533)
Income tax expense (benefit)									(137)	(969)	(578)
Net income									(1,725)	(975)	(955)
Total assets	(604)				6,005				(604)	6,005	4,973
Capital expenditures									14	42	1
Operating Segments | Retail Banking
Revenues:
Interest income									49,564	46,071	42,960
Other noninterest income									10,633	11,400	9,083
Total operating income									60,197	57,471	52,043
Expenses:
Provision for loan losses									200
Interest expense									6,076	5,790	5,682
Salaries and employee benefits									25,264	24,613	23,185
Other noninterest expenses									17,951	17,433	17,155
Total operating expenses									49,491	47,836	46,022
Income (loss) before income taxes									10,706	9,635	6,021
Income tax expense (benefit)									5,727	1,425	392
Net income									4,979	8,210	5,629
Total assets	1,341,879				1,290,733				1,341,879	1,290,733	1,233,976
Goodwill	3,702				3,702				3,702	3,702	3,702
Capital expenditures									3,352	2,376	1,597
Operating Segments | Mortgage Banking
Revenues:
Interest income									1,660	1,689	1,698
Gains on sales of loans									8,553	8,120	6,336
Other noninterest income									4,653	3,913	2,621
Total operating income									14,866	13,722	10,655
Expenses:
Provision for loan losses											45
Interest expense									587	435	310
Salaries and employee benefits									6,503	5,664	4,594
Other noninterest expenses									5,185	4,815	4,563
Total operating expenses									12,275	10,914	9,512
Income (loss) before income taxes									2,591	2,808	1,143
Income tax expense (benefit)									1,606	1,121	466
Net income									985	1,687	677
Total assets	69,537				65,351				69,537	65,351	58,206
Capital expenditures									410	314	100
Operating Segments | Consumer Finance
Revenues:
Interest income									44,745	47,150	47,053
Other noninterest income									995	921	1,095
Total operating income									45,740	48,071	48,148
Expenses:
Provision for loan losses									16,235	18,040	15,467
Interest expense									8,164	7,073	6,201
Salaries and employee benefits									9,389	10,102	9,758
Other noninterest expenses									5,421	5,437	4,970
Total operating expenses									39,209	40,652	36,396
Income (loss) before income taxes									6,531	7,419	11,752
Income tax expense (benefit)									4,198	2,882	4,573
Net income									2,333	4,537	7,179
Total assets	292,438				306,012				292,438	306,012	295,430
Goodwill	10,723				10,723				10,723	10,723	10,723
Capital expenditures									232	386	211
Eliminations
Revenues:
Interest income									(6,377)	(5,473)	(4,662)
Total operating income									(6,377)	(5,473)	(4,662)
Expenses:
Interest expense									(6,377)	(5,473)	(4,662)
Total operating expenses									(6,377)	(5,473)	(4,662)
Total assets	$ (194,194)				$ (216,109)				$ (194,194)	$ (216,109)	$ (187,509)