Fair Value - Schedule of Financial Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Assets:
Restricted cash	$ 746	$ 1,854	$ 868
Total assets measured and recorded at fair value	1,048,224	517,333
Level 1
Assets:
Restricted cash	746	1,854
Total assets measured and recorded at fair value	1,048,224	517,333
Cash
Assets:
Cash and cash equivalents	975,685	463,820
Cash | Level 1
Assets:
Cash and cash equivalents	975,685	463,820
Money Market Fund
Assets:
Cash and cash equivalents	71,793	51,659
Money Market Fund | Level 1
Assets:
Cash and cash equivalents	$ 71,793	$ 51,659