Investments in Affiliates (Equity Method Investment, Summarized Financial Data) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Assets:
Current assets	$ 86,091		$ 86,091			$ 260,965
Total assets	230,029		230,029			390,810
Liabilities and Shareholder's Equity:
Current liabilities	4,565		4,565			5,494
Total liabilities	39,846		39,846			40,783
Stockholder's Equity	190,183	$ 351,243	190,183	$ 351,243	$ 146,231	350,027	$ 361,257	$ 297,566
Statement of Operations Data:
Operating income (loss)	4,129	(1,615)	680	(5,115)
Interest expense	(9)	(5)	(20)	(15)
Income tax (provision) benefit	(309)	(1,275)	(956)	(5,501)
Telesat Holdings Inc [Member]
Assets:
Current assets	990,985		990,985			877,294
Total assets	4,094,795		4,094,795			4,130,337
Liabilities and Shareholder's Equity:
Current liabilities	151,645		151,645			124,217
Long-term debt, including current portion	2,824,838		2,824,838			2,836,700
Total liabilities	3,448,067		3,448,067			3,504,594
Stockholder's Equity	646,728		646,728			$ 625,743
Statement of Operations Data:
Revenues	152,081	180,180	460,407	520,819
Operating expenses	(33,322)	(29,038)	(103,717)	(102,536)
Depreciation and amortization	(44,888)	(52,259)	(133,336)	(155,036)
Other operating income (expense)	(26)	(45)	(182)	(110)
Operating income (loss)	73,845	98,838	223,172	263,137
Interest expense	(37,715)	(46,239)	(115,947)	(139,574)
Foreign exchange (loss) gain	48,943	(24,702)	(74,387)	73,713
Gain (loss) on financial instruments	246	(4,244)	(11,643)	(40,619)
Other income (expense)	1,524	4,497	7,476	12,603
Income tax (provision) benefit	(9,053)	(15,548)	(18,509)	(26,584)
Net income (loss)	$ 77,790	$ 12,602	$ 10,162	$ 142,676