Revenue - Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Unbilled Receivables
Beginning Balance	$ 144	$ 90
Reclassifications to billed receivables	(144)	(90)
Revenues recognized in excess of period billings	108	1,641
Ending Balance	108	1,641
Deferred Revenue
Beginning Balance	50,634	113,319
Revenues recognized from balances held at the beginning of the period	(2,525)	(6,704)
Revenues deferred from period collections on unfulfilled performance obligations	0	10,025
Revenues recognized from period collections	0	(872)
Ending Balance	$ 48,109	$ 115,768