Revenues Revenues - Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017
Change in Contract with Customer, Liability [Roll Forward]
Beginning Balance	$ 72,358
New deferrals	111,812	$ 104,900
Revenue recognized	(114,100)	(106,020)
Ending Balance	$ 70,070	$ 73,478