Income Taxes - Components of Income Tax Expense ( benefit) (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Current Federal expense		$ 16,000		$ 35,000
Current state and local tax expense	$ 18,000	16,000	$ 35,000	188,000
Deferred Federal tax (benefit) expense	(94,000)	103,000	(128,000)	(370,000)
Deferred state and local tax (benefit) expense	(45,000)	6,000	(72,000)	(134,000)
Income tax (benefit) expense	$ (121,000)	$ 141,000	$ (165,000)	$ (281,000)