Fair Value - Schedule of Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Assets:
Restricted cash, current		$ 434	$ 746
Restricted cash, non-current	$ 1,512
Total assets measured and recorded at fair value	2,181,257	1,093,249
Level 1
Assets:
Restricted cash, current		434
Restricted cash, non-current	1,512
Total assets measured and recorded at fair value	2,181,257	1,093,249
Cash
Assets:
Cash and cash equivalents	1,736,948	1,021,022
Cash | Level 1
Assets:
Cash and cash equivalents	1,736,948	1,021,022
Money Market Funds
Assets:
Cash and cash equivalents	442,797	71,793
Money Market Funds | Level 1
Assets:
Cash and cash equivalents	$ 442,797	$ 71,793