Investments in Affiliates (Equity in Net Income (Losses) of Affiliates) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Schedule of Equity Method Investments [Line Items]
Equity in net income (loss) of affiliates	$ (3,455)	$ 1,639	$ 139,714
Telesat Canada [Member]
Schedule of Equity Method Investments [Line Items]
Equity in net income (loss) of affiliates	$ (3,455)	$ 1,639	$ 139,714