Development and Other Agreements - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Nov. 20, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 28, 2018
Development Agreements [Line Items]
Collaborative research and development fee		$ 0.0	$ 0.0	$ 217.7
Collaborative Arrangement \| Verily Life Sciences \| Collaborative Arrangement, Initial Payment
Development Agreements [Line Items]
Initial payment on collaborative agreement	$ 250.0
Issuance of common stock in connection with acquisition, shares (in shares)	1,840,943
Collaborative research and development fee				$ 217.7
Closing stock price (USD per share)					$ 118.28
Collaborative Arrangement \| Verily Life Sciences \| Collaborative Arrangement, Milestone Payments
Development Agreements [Line Items]
Collaborative research and development fee		$ 0.0	$ 3.2
Additional milestones and incentive payments	$ 275.0
Milestone payments due upon achievement of future development	$ 275.0
Potential future common stock issuable (shares)		2,025,036
Consecutive days used to calculate volume weighted average trading price	15 days