Commitments and Contingencies - Concentrations of Credit Risk (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) customer	Mar. 31, 2020 USD ($) customer	Dec. 31, 2020 customer
Customer Concentration
Restricted cash | $	$ 198,600
Consolidated revenue | $	71,958	$ 40,819
Letter of Credit
Customer Concentration
Letters of credit backed by restricted cash | $	$ 144,400
Accounts receivable | Customer concentration | Two customers
Customer Concentration
Number of customers	2
Concentration risk (as a percent)	67.70%
Accounts receivable | Customer concentration | Three customers
Customer Concentration
Number of customers			3
Concentration risk (as a percent)			73.90%
Revenues | Customer concentration | Two customers
Customer Concentration
Number of customers		2
Concentration risk (as a percent)		65.90%
Revenues | Customer concentration | Three customers
Customer Concentration
Number of customers	3
Concentration risk (as a percent)	71.20%