Revenue and Customers - Receivables, Contract Assets, and Contract Liabilities with Customers (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Current contract assets	$ 17,085	$ 21,292
Noncurrent contract assets	7,494	9,508
Total contract assets	24,579	30,800	$ 39,262	$ 47,664
Current contract liabilities (deferred revenue)	(42,535)	(34,196)
Noncurrent contract liabilities (deferred revenue)	(26,171)	(30,859)
Total contract liabilities	$ (68,706)	$ (65,055)	$ (72,264)	$ (80,753)