Revenue and Customers - Significant Changes in Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract assets, beginning balance	$ 47,664	$ 55,749
Contract liabilities, beginning balance	(80,753)	(108,861)
Amortization of deferred costs	(39,936)	(32,420)
Additions to deferred costs	23,072	24,335
Amortization of deferred revenue	(65,312)	(47,798)
Additions to deferred revenue	(49,614)	(19,690)
Total	(16,864)	(8,085)
Total	15,698	28,108
Contract assets, ending balance	30,800	47,664
Contract liabilities, ending balance	$ (65,055)	$ (80,753)