Income Taxes - Schedule of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. Federal:
Current	$ 0	$ 0	$ 0
Deferred	(57,637)	(5,488)	13,629
U. S. Federal Income Tax Expense (Benefit)	(57,637)	(5,488)	13,629
U.S. State:
Current	199	427	284
Deferred	(717)	3,218	(740)
State and Local Income Tax Expense (Benefit)	(518)	3,645	(456)
Foreign Income Tax Expense (Benefit), Continuing Operations [Abstract]
Foreign	108	1,374	3,159
Deferred	(926)	0	0
Foreign Income Tax Expense (Benefit)	(818)	1,374	3,159
Total	$ (58,973)	$ (469)	$ 16,332