Acquisitions - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended			6 Months Ended
	Sep. 30, 2020	Feb. 28, 2019	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Oscine Corp
Business Acquisition [Line Items]
Business acquisition, consideration transferred	$ 8,500,000
Oscine Corp | Stock Purchase Agreement
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%			100.00%
Business acquisition, consideration transferred	$ 8,500,000			$ 8,500,000
Business acquisition, consideration transferred, cash	7,600,000
Business acquisition, consideration holdback amount	900,000
Oscine Corp | Stock Purchase Agreement | Maximum
Business Acquisition [Line Items]
Future milestone payments upon achievement of certain development and commercial milestones	$ 225,800,000			$ 225,800,000
Cobalt Biomedicine, Inc | Acquisition Agreement
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired		100.00%
Maximum success payment upon achievement of certain pre-specified development milestones		$ 500,000,000.0
Maximum period for success payment to achieve		20 years
Cobalt Biomedicine, Inc | Acquisition Agreement | Research and Development
Business Acquisition [Line Items]
Estimated fair value of success payment liability			$ 89,800,000			$ 89,800,000		$ 64,700,000
Estimated fair value of contingent consideration			140,500,000			140,500,000		$ 121,900,000
(Gain) expense in connection with change in estimated fair value of success payment			(66,600,000)		$ 33,500,000	25,100,000	$ 33,900,000
Expense in connection with change in estimated fair value of contingent consideration			$ 7,200,000		$ 14,000,000.0	$ 18,600,000	$ 14,300,000
Cobalt Biomedicine, Inc | Acquisition Agreement | Market Capitalization Equal to or Exceeds $8.1 billion
Business Acquisition [Line Items]
Cobalt success payment		$ 500,000,000.0
Cobalt Biomedicine, Inc | Acquisition Agreement | Minimum [Member]
Business Acquisition [Line Items]
Threshold market capitalization		$ 8,100,000,000