Investments in Affiliates (Equity Method Investment, Summarized Financial Data) (Details) - Telesat Canada [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Summary Financial Data:
Current assets	$ 699,031		$ 628,125
Total assets	4,033,388		3,942,847
Current liabilities	141,528		139,401
Long-term debt, including current portion	2,760,180		2,764,599
Total liabilities	3,497,603		3,474,504
Shareholders' equity	535,785		$ 468,343
Revenues	167,644	$ 184,866
Operating expenses	(37,979)	(30,603)
Depreciation, amortization and stock-based compensation	(53,798)	(48,499)
Other operating income (expense)	(55)	2
Operating income	75,812	105,766
Interest expense	(46,843)	(45,088)
Foreign exchange (loss) gain	52,469	(63,301)
Gain (loss) on financial instruments	(15,112)	32,383
Other income (expense)	3,834	1,618
Income tax provision	(4,555)	(23,770)
Net (loss) income	$ 65,605	$ 7,608