Investments in Affiliates (Equity in Net Income (Losses) of Affiliates) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity in net income (loss) of affiliates	$ 5,094	$ 139,714
Telesat Canada [Member]
Schedule of Equity Method Investments [Line Items]
Equity in net income (loss) of affiliates	$ 5,094	$ 139,714