Summary of Significant Accounting Policies (as Restated) - Summary of Effect on Individual Line Items Within Operating Cash Flows on Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands		3 Months Ended										6 Months Ended		9 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2019	Mar. 19, 2019	Mar. 19, 2019	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2018
Net (loss) income	$ (30,279)	$ (71,375)	$ (47,547)	$ (20,693)	$ (148,362)	$ (6,885)	$ 4,270	$ (29,320)	$ 959	$ (24,781)	$ (24,781)	$ (169,055)	$ (25,050)	$ (216,602)	$ (31,935)	$ (31,935)	$ (287,977)	$ 13,743
Change in fair value of warrant liabilities	7,700	43,400	25,100	(12,100)	(50,300)	9,000	(600)	11,300	3,600			(62,400)	10,700	(37,300)	19,700	19,700	6,100
Warrant issuance costs																	1,386
Net cash provided by (used in) financing activities											$ 3,733				(3,174)	$ (3,174)	(36,550)	$ 32,387
As Reported [Member]
Net (loss) income	(22,579)	(27,975)	(22,447)	(31,407)	(198,662)	2,115	3,670	(18,020)	4,559			(230,069)	(14,350)	(252,516)	(12,235)		(280,491)
Net cash provided by (used in) financing activities															(3,174)		(36,550)
Restatement Impact [Member]
Net (loss) income	(7,700)	(43,400)	(25,100)	10,714	50,300	(9,000)	600	(11,300)	(3,600)			61,014	(10,700)	35,914	(19,700)		(7,486)
Change in fair value of warrant liabilities	$ 7,700	$ 43,400	$ 25,100	$ (12,100)	$ (50,300)	$ 9,000	$ (600)	$ 11,300	$ 3,600			$ (62,400)	$ 10,700	$ (37,300)	$ 19,700		6,100
Warrant issuance costs																	$ 1,386