Income Taxes - Loss from Continuing Operations Before Benefit for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest [Abstract]
United States	$ (146,963)	$ (31,760)	$ (200,164)
Foreign	(5,125)	(365)	(8,214)
Loss from continuing operations before benefit (provision) for income taxes and share of net income (loss) from joint venture	$ (152,088)	$ (32,125)	$ (208,378)