Basis of Presentation (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Basis of Presentation [Line Items]
Cash and cash equivalents		$ 256,947	$ 255,139
Restricted cash		$ 304	304
Net benefit cost			$ 1,600
U.S. federal corporate income tax rate		21.00%	35.00%
Equity Method Investments [Member]
Basis of Presentation [Line Items]
Investments in affiliates, guarantee or other funding obligations		$ 0	$ 0
Sale of SSL, Nov. 02, 2012 [Member]
Basis of Presentation [Line Items]
Disposal segment, sale date		Nov. 02, 2012
Date purchase agreement entered into		Jun. 26, 2012
Date of first modification of purchase agreement		Oct. 30, 2012
Date of second modification of purchase agreement		Mar. 28, 2013
Adjustments for New Accounting Pronouncement [Member] | Other Expense [Member]
Basis of Presentation [Line Items]
Defined benefit cost, non-service component reversed			900
Accounting Standards Update 2016-02 [Member]
Basis of Presentation [Line Items]
Right-of-use and lease liability		$ 300
ViaSat Lawsuit, Sep. 2014 [Member] | Sale of SSL, Nov. 02, 2012 [Member]
Basis of Presentation [Line Items]
Payments for legal settlements	$ 2,800
Accumulated Deficit [Member]
Basis of Presentation [Line Items]
Tax Cuts and Jobs Act, reclassification tax effect		4,173	4,468
Accumulated Other Comprehensive Loss [Member]
Basis of Presentation [Line Items]
Tax Cuts and Jobs Act, reclassification tax effect		$ (4,173)	$ (4,468)