Income Taxes - Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amounts
Income tax at statutory rates	$ 4,734	$ 6,288	$ 6,272
State income taxes	575	348	403
Tax-exempt interest income	(592)	(1,162)	(1,367)
Carrying cost of tax-exempt assets	18	32	36
Share-based compensation	(103)	(284)	(255)
Change in value of bank-owned life insurance	(89)	(151)	(324)
Investments in qualified housing projects	(85)	(135)	(147)
Remeasurement of net deferred tax assets		6,643
Other	63	(185)	(159)
Income tax expense (benefit)	$ 4,521	$ 11,394	$ 4,459
Percent of Pre-tax Income
Income tax at statutory rates (as a percent)	21.00%	35.00%	35.00%
State income taxes (as a percent)	2.60%	1.90%	2.20%
Tax-exempt interest income (as a percent)	(2.60%)	(6.50%)	(7.60%)
Carrying cost of tax-exempt assets (as a percent)	0.10%	0.20%	0.20%
Share-based compensation (as a percent)	(0.50%)	(1.60%)	(1.40%)
Change in value of bank-owned life insurance (as a percent)	(0.40%)	(0.80%)	(1.80%)
Investments in qualified housing projects (as a percent)	(0.40%)	(0.80%)	(0.80%)
Remeasurement of net deferred tax assets (as a percent)		37.00%
Other (as a percent)	0.30%	(1.00%)	(0.90%)
Income tax expense (as a percent)	20.10%	63.40%	24.90%