Income Taxes - Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Current Federal alternative minimum tax ("AMT") (benefit) expense	$ (8)	$ 8	$ 27	$ 149
Current state and local tax (benefit) expense	(8)	(49)	180	111
Deferred Federal tax expense (benefit)	256	245	(114)	1,490
Deferred state and local tax expense (benefit)	46	93	(88)	114
Income tax expense	$ 286	$ 297	$ 5	$ 1,864