Significant Accounting Policies - Assessment of Revenue under ASC 606 (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020
Amounts Invoiced and Not Collected
Beginning balance, gross	$ 48,883
Beginning balance, net		$ 9,006
Ending balance, net	9,006	1,239
Deferred Cost of Sales
Ending balance, gross	6,415
Beginning balance, net		1,261
Ending balance, net	1,261	174
Accounting Standards Update 2014-09
Amounts Invoiced and Not Collected
Beginning balance, gross		(29,604)
Transition Adjustment during the three months ended September 30, 2019	(21,385)
Cash collected related to the Remaining Contracts	(8,219)	(7,767)
Ending balance, gross	(29,604)
Write-off of customer contracts where collection is no longer reasonably assured	(10,273)
Cash collected related to the Remaining Contracts	(8,219)	(7,767)
Deferred Cost of Sales
Ending balance, gross		(3,716)
Transition Adjustment during the three months ended September 30, 2019	(2,565)
Cash collected related to the Remaining Contracts	(1,151)	(1,087)
Beginning balance, gross	(3,716)
Write-off of customer contracts where collection is no longer reasonably assured	(1,438)
Cash collected related to the Remaining Contracts	$ (1,151)	$ (1,087)