License, Collaboration and Other Significant Agreements - Mitsubishi Tanabe Pharma Corporation Collaboration Agreement (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) performance_obligation	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	$ 48,756,000	$ 59,988,000		$ 153,973,000	$ 238,608,000
Deferred revenue	43,657,000			43,657,000
Revenue recognized	9,159,000	6,537,000		20,363,000	29,203,000
Deferred revenue, net of current portion	27,965,000			27,965,000		$ 25,345,000
Short-term deferred revenue	15,692,000			15,692,000		15,214,000
Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable	21,413,000	2,761,000		21,413,000	2,761,000	$ 3,045,000	$ 15,822,000
License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	12,003,000	25,596,000		53,853,000	144,311,000
Mitsubishi Tanabe Pharma Corporation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue				900,000
Mitsubishi Tanabe Pharma Corporation | License, collaboration and other revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	2,555,000	373,000		7,167,000	15,373,000
Mitsubishi Tanabe Pharma Corporation | License Collaboration And Other Revenue, Royalties
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Recognized revenue	300,000			400,000
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue				$ 25,000,000
Mitsubishi Tanabe Pharma Corporation | MTPC Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of performance obligations | performance_obligation				2
Deferred revenue	4,883,000			$ 4,883,000
Deferred revenue, net of current portion	0			0
Short-term deferred revenue	4,883,000			4,883,000
Mitsubishi Tanabe Pharma Corporation | MTPC Agreement | Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue					15,000,000
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received				20,000,000
Cost of research services				20,500,000
Milestone revenue				10,000,000
Deferred revenue	0			0
Accounts receivable	0			0
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement | Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue				10,000,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation And Otsuka Pharmaceutical Company Limited
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received			$ 10,400,000
Accounts receivable	0			0
Revenue recognized	0	$ 500,000		0	$ 4,500,000
Deferred revenue, net of current portion	0			0
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation And Otsuka Pharmaceutical Company Limited | Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable	200,000			200,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation And Otsuka Pharmaceutical Company Limited | Other Current Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Short-term deferred revenue	3,000,000			3,000,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation And Otsuka Pharmaceutical Company Limited | Other Noncurrent Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue, net of current portion	400,000			400,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	2,200,000			6,700,000
Up-front payments invoiced	13,400,000			13,400,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement | Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Up-front payments invoiced	4,500,000			4,500,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement | Other Current Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Up-front payments invoiced	16,300,000			16,300,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement | Other Noncurrent Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Up-front payments invoiced	5,800,000			5,800,000
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement | Contract With Customer, Liability
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Up-front payments invoiced	$ 4,900,000			$ 4,900,000