Revenue and Customers - Receivables, Contract Assets, and Contract Liabilities with Customers (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Current contract assets	$ 21,292	$ 25,298
Noncurrent contract assets	9,508	22,366
Total contract assets	30,800	47,664	$ 55,749
Current contract liabilities (deferred revenue)	(34,196)	(32,906)
Noncurrent contract liabilities (deferred revenue)	(30,859)	(47,847)
Total contract liabilities	$ (65,055)	$ (80,753)	$ (108,861)