Components of Income Tax Benefit (Provision) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Current benefit (provision), Federal	$ 64,000	$ (9,000)	$ (268,000)
Deferred benefit (provision), Federal	583,000	(2,127,000)	(2,110,000)
Income tax benefit (provision), Federal	647,000	(2,136,000)	(2,378,000)
Current benefit (provision), State and Local	220,000	(329,000)	(46,000)
Deferred benefit (provision), State and Local	(6,000)	(85,000)	(374,000)
Income tax benefit (provision), State and Local	214,000	(414,000)	(420,000)
Income tax benefit (provision), Foreign	0	0	0
Current benefit (provision), Total	284,000	(338,000)	(314,000)
Deferred benefit (provision), Total	577,000	(2,212,000)	(2,484,000)
Income tax benefit (provision)	$ 861,000	$ (2,550,000)	$ (2,798,000)