Investments - Continuous Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	$ (106)	$ (12)
Fair Value	144,298	128,502
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(81)	(6)
Fair Value	54,963	65,298
U.S. agency and government sponsored securities
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(3)	0
Fair Value	4,991	0
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(8)	(4)
Fair Value	60,957	47,629
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Gross Unrealized Losses	(14)	(2)
Fair Value	$ 23,387	$ 15,575