Convertible Senior Notes - Schedule of Interest Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
0.375% Convertible Senior Notes Due 2025 [Member]
Debt Instrument [Line Items]
Contractual interest expense	$ 1,725	$ 987
Amortization of debt discount	18,171	9,974
Amortization of issuance costs	1,428	784
Total interest expense	21,324	11,745
0.25% Convertible Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Contractual interest expense	154	614	$ 1,000
Amortization of debt discount	3,636	13,150	20,277
Amortization of issuance costs	272	982	1,513
Total interest expense	$ 4,062	$ 14,746	$ 22,790