Revenues Revenues - Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Change in Contract with Customer, Liability [Roll Forward]
Beginning Balance	$ 70,070	$ 72,358
New deferrals	101,066	111,812
Revenue recognized	(93,488)	(114,100)
Ending Balance	$ 77,648	$ 70,070