Description of Business - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended
		Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Nov. 30, 2020	Dec. 31, 2019	Aug. 31, 2019
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Accumulated deficit			$ (3,130,069)	$ (3,049,143)
Principal amount			288,400
Cash and cash equivalents			124,184	67,005
Short-term investments			79,932
Long-term investments			56,619
Debt issuance amount		$ 230,000
Debt issuance percentage		2.50%
MidCap Credit Facility
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Principal amount	[1]		$ 40,000	$ 50,000
Principal amount							$ 100,000
Amount outstanding						$ 40,000
Minimum cash covenant					$ 30,000		$ 90,000

[1] In April 2021, the Company prepaid $10.0 million principal balance and amended the MidCap credit facility. The interest rate prior to the amendment was one-month LIBOR (2% floor) plus 6.75% and the maturity date was in August 2024.