Investments in Affiliates (Equity Method Investment, Summarized Financial Data) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Current assets	$ 34,091	$ 260,965
Total assets	254,469	390,810
Liabilities and Shareholder's Equity:
Current liabilities	4,841	5,494
Total liabilities	44,936	40,783
Stockholder's Equity	209,533	350,027	$ 297,566
Statement of Operations Data:
Operating income (loss)	(863)	(6,612)
Interest expense	(26)	(24)
Income tax (provision) benefit	(12,886)	(6,153)
Telesat Holdings Inc [Member]
Assets:
Current assets	703,210	877,294
Total assets	3,943,875	4,130,337
Liabilities and Shareholder's Equity:
Current liabilities	129,849	124,217
Long-term debt, including current portion	2,483,256	2,836,700
Total liabilities	3,140,747	3,504,594
Stockholder's Equity	803,128	625,743
Statement of Operations Data:
Revenues	613,866	687,868
Operating expenses	(136,262)	(141,136)
Depreciation and amortization	(174,526)	(200,838)
Impairment of intangible asset	(3,410)	0
Other operating income (expense)	(160)	(649)
Operating income (loss)	299,508	345,245
Interest expense	(152,236)	(186,394)
Loss on refinancing	0	(86,166)
Foreign exchange gain (loss)	35,655	122,002
Loss on financial instruments	(13,305)	(42,039)
Other income (expense)	5,294	16,282
Income tax (provision) benefit	3,721	(12,741)
Net income (loss)	$ 178,637	$ 156,189