Revenue - Change in Deferred Revenue (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Movement in Deferred Revenue [Roll Forward]
Deferred revenue at December 31, 2018	$ 164,925
Deferral of revenue billed in current period, net of recognition	74,985
Recognition of revenue deferred in prior periods	(77,380)
Divestiture of AWR subsidiary	(15,296)
Foreign currency translation impact	(981)
Deferred revenue as of September 30, 2019	$ 146,253