Income Taxes - Summary of Benefit (Provision) for Income Taxes from Continuing Operation (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
United States federal									$ 0	$ (1,649)	$ (1,426)
State and local									(5)	859	(12)
Foreign									(448)	(442)	(389)
Total current									(453)	(1,232)	(1,827)
Deferred:
United States federal									0	(24,261)	585
State and local									0	0	0
Foreign									(27)	(28)	(349)
Total deferred									(27)	(24,289)	236
Income tax, total	$ (185)	$ (44)	$ (99)	$ (152)	$ (26,785)	$ (3,760)	$ (3,323)	$ (1,701)	$ (480)	$ (25,521)	$ (1,591)