Investments - Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	$ (922)	$ (12)
Fair Value	372,482	128,502
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(474)	(6)
Fair Value	146,454	65,298
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(25)	0
Fair Value	4,970	0
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(4)	(4)
Fair Value	30,285	47,629
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(345)	(2)
Fair Value	145,522	15,575
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(74)	0
Fair Value	$ 45,251	$ 0