Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Significant Accounting Policies [Line Items]
Amortization period of deferred issuance costs	5 years
Reduction to equity	$ (219,727)	$ (236,392)	$ (306,948)		$ (114,688)	$ (135,134)	$ (104,151)
Reduction to accumulated deficit / increase to retained earnings	(589,231)		(542,030)
Additional Paid-in Capital
Significant Accounting Policies [Line Items]
Reduction to equity	(809,015)	(798,589)	(848,891)		(611,955)	(605,622)	(535,954)
Accumulated Deficit
Significant Accounting Policies [Line Items]
Reduction to equity	$ 589,231	$ 562,211	542,030		$ 497,709	$ 470,576	$ 431,952
Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Reduction to equity			51,012
Reduction to accumulated deficit / increase to retained earnings			7,500
Cumulative Effect, Period of Adoption, Adjustment | Additional Paid-in Capital
Significant Accounting Policies [Line Items]
Reduction to equity			58,543
Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Significant Accounting Policies [Line Items]
Reduction to equity			$ (7,531)
Senior Notes | Convertible Notes
Significant Accounting Policies [Line Items]
Debt instrument stated rate				2.625%