Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Liabilities:
Warrants liability	$ 0	$ 42,452
Recurring Basis
Assets:
Total	1,147,989	279,279
Liabilities:
Total		42,452
Recurring Basis | Level 1
Assets:
Total	1,147,989	279,279
Liabilities:
Warrants liability		0
Total		0
Recurring Basis | Level 2
Assets:
Total	0	0
Liabilities:
Warrants liability		0
Total		0
Recurring Basis | Level 3
Assets:
Total	0	0
Liabilities:
Warrants liability		42,452
Total		42,452
Recurring Basis | Certificates of deposit
Assets:
Cash equivalents	0	279,279
Recurring Basis | Certificates of deposit | Level 1
Assets:
Cash equivalents	0	279,279
Recurring Basis | Certificates of deposit | Level 2
Assets:
Cash equivalents	0	0
Recurring Basis | Certificates of deposit | Level 3
Assets:
Cash equivalents	0	$ 0
Recurring Basis | Money market funds
Assets:
Cash equivalents	1,147,989
Recurring Basis | Money market funds | Level 1
Assets:
Cash equivalents	1,147,989
Recurring Basis | Money market funds | Level 2
Assets:
Cash equivalents	0
Recurring Basis | Money market funds | Level 3
Assets:
Cash equivalents	$ 0