Indebtedness - Summary of Debt Facilities (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Nov. 14, 2017
Debt Instrument [Line Items]
Principal amount	$ 1,119,993,000
Total carrying value of debt facilities	1,091,110,000	$ 992,493,000
2024 Convertible Notes [Member]
Debt Instrument [Line Items]
Principal amount	569,993,000	569,993,000	$ 570,000,000.0
Unamortized discount		(98,721,000)
Unamortized discount - debt issuance costs	(7,913,000)	(6,510,000)
Net carrying value	562,080,000	464,762,000
2019 Term Loan [Member]
Debt Instrument [Line Items]
Principal amount	550,000,000	550,000,000
Unamortized discount	(20,970,000)	(22,269,000)
Net carrying value	$ 529,030,000	$ 527,731,000

Face (par) amount of debt instrument at time of issuance.

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