Federal and State Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax (benefit) expense at statutory federal rate									$ 3,481	$ (2,190)	$ (3,926)
Federal income tax effects of:
State income tax expense (benefit)									(155)	76	188
Per diem and other nondeductible meals and entertainment									329	578	614
Impact of Tax Cuts and Jobs Act									0	(12,010)	0
Other									(19)	0	143
Federal income tax (benefit) expense									3,636	(13,546)	(2,981)
State income tax (benefit) expense									738	(214)	(538)
Total income tax (benefit) expense	$ 1,862	$ 1,272	$ 821	$ 419	$ (10,291)	$ 339	$ (1,198)	$ (2,610)	$ 4,374	$ (13,760)	$ (3,519)
Effective tax rate									26.40%	219.90%	31.40%