Convertible Senior Notes - Schedule of Interest Expense Related to Notes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Instrument [Line Items]
Contractual Interest Expense	$ 1,219
Amortization of Issuance Costs	1,172	$ 0
Total interest expense	2,391
Convertible Senior Notes due 2025
Debt Instrument [Line Items]
Contractual Interest Expense	1,219
Amortization of Issuance Costs	739
Total interest expense	1,958
Convertible Senior Notes due 2027
Debt Instrument [Line Items]
Contractual Interest Expense	0
Amortization of Issuance Costs	433
Total interest expense	$ 433