Components of Income Tax Benefit (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Current income tax expense (benefit):
Foreign	$ (17)	$ 62	$ (35)	$ 326
U.S. Federal	0	(732)	0	0
Total current income tax expense (benefit)	(17)	(670)	(35)	326
Deferred income tax expense (benefit):
U.S. Federal	(300)	(2,622)	5,198	(6,270)
Total deferred income tax expense (benefit)	(300)	(2,622)	5,198	(6,270)
Total income tax expense (benefit)	$ (317)	$ (3,292)	$ 5,163	$ (5,944)