Summary of Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Summary of Significant Accounting Policies
Net Receivables, Opening balance	$ 16,944	$ 15,321
Net Receivables, Closing balance	18,758	15,451
Increase/(decrease)	1,814	130
Contract Liabilities, Current, Opening balance	14	18
Contract Liabilities, Current, Closing balance	14	14
Increase/(decrease)		(4)
Contract Liabilities, Long-Term, Opening balance	15	42
Contract Liabilities, Long-Term, Closing balance	6	22
Increase/(decrease)	$ (9)	$ (20)