Supplemental Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Employee benefits paid in Class A common stock			$ 7,605	$ 11,200
Property and equipment financed under capital lease obligations			187	8,423
Increase (decrease) in capital expenditures included in accounts payable, net			17,058	(3,494)
Capitalized in-orbit incentive obligations			0	43,890
Noncash net assets exchanged for Tracking Stock (Note 1)			0	299,425
Restricted Cash and Cash Equivalents [Abstract]
Restricted cash	$ 800	$ 800	800	800	$ 800	$ 700
Research and Development Expense [Abstract]
Research and development expenses	6,544	8,302	20,328	23,444
Capitalized Software Costs
Payments to develop software			24,568	25,447
Other noncurrent assets, net
Capitalized Software Costs
Capitalized computer software, net	95,700		95,700		88,100
Capitalized software development costs for software sold to customers	31,300		31,300		19,600
Payments to develop software	9,600	8,300	24,600	25,400
Capitalized computer software, amortization	5,800	5,500	$ 16,900	14,100
Weighted Average
Capitalized Software Costs
Software useful life			3 years
Contract Acquisition Costs
Capitalized Contract Cost [Abstract]
Contract acquisition costs	104,500		$ 104,500
Contract acquisition costs, amortization	21,000		61,700
Contract Fulfillment Costs
Capitalized Contract Cost [Abstract]
Contract acquisition costs	2,600		2,600
Level 2
Fair value measurements
In-orbit incentive obligations	107,600		107,600		$ 112,200
Cost of Sales
Research and Development Expense [Abstract]
Research and development expenses	5,555	7,038	18,443	20,724
Research and development expenses
Research and Development Expense [Abstract]
Research and development expenses	$ 6,544	$ 8,302	$ 20,328	$ 23,444