Income Taxes - Reconciliation of Differences Between Federal Income Tax Rate and Total Income Tax Expense (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 Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Income tax, at federal rate									$ 799	$ (1,007)	$ 826
State and local tax, net of federal taxes									(536)	(1,340)	(341)
Valuation allowance, net of the federal benefit									790	1,606	493
Expense (benefit) due to enactment of federal tax reform										2,113
Other									68	52	27
Provision (benefit) for income taxes	$ 498	$ 188	$ 166	$ 268	$ 2,081	$ (1,643)	$ 641	$ 345	$ 1,121	$ 1,424	$ 1,005