Summary of Significant Accounting Policies - Concentration of Risk (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Summary of Significant Accounting Policies
Accounts receivable	$ 0	$ 1,660,000
Contract revenue | Customer risk
Summary of Significant Accounting Policies
Number of customers	1	2
Contract revenue | Customer 1 | Customer risk
Summary of Significant Accounting Policies
Concentration risk percentage	100.00%	58.00%
Contract revenue | Customer 2 | Customer risk
Summary of Significant Accounting Policies
Concentration risk percentage		42.00%
Accounts receivable | Customer risk
Summary of Significant Accounting Policies
Number of customers		2
Accounts receivable | Customer 1 | Customer risk
Summary of Significant Accounting Policies
Concentration risk percentage	60.00%	60.00%
Accounts receivable | Customer 2 | Customer risk
Summary of Significant Accounting Policies
Concentration risk percentage		40.00%