Revenue and Customers - Significant Changes in Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract assets, beginning balance	$ 30,800	$ 47,664
Contract liabilities, beginning balance	(65,055)	(80,753)
Amortization of deferred costs	(8,799)	(8,775)
Additions to deferred costs	2,578	373
Amortization of deferred revenue	15,828	9,355
Additions to deferred revenue	(19,479)	(866)
Total	(6,221)	(8,402)
Total	(3,651)	8,489
Contract assets, ending balance	24,579	39,262
Contract liabilities, ending balance	$ (68,706)	$ (72,264)