Accumulated Other Comprehensive Income (Loss) (Components of Other Comprehensive Income and Related Tax Effects) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Net actuarial gain (loss) and prior service credits, Before-Tax Amount		$ (2,921)	$ 1,208
Amortization of prior service credits and net actuarial loss, Before-Tax Amount	[1]	1,008	1,071
Pension amd other postretirement benefits, Before-Tax Amount		(1,913)	2,279
Proportionate share of Telesat Holdco other comprehensive income (loss), Before-Tax Amount		(35,793)	22,033
Other comprehensive income (loss), Before-Tax Amount		(37,706)	24,312
Net actuarial gain (loss) and prior service credits, Tax (Provision) Benefit		614	(255)
Amortization of prior service credits and net actuarial loss, Tax (Provision) Benefit		(212)	(226)
Pension amd other post retirement benefits, Tax (Provision) Benefit		402	(481)
Proportionate share of Telesat Holdco other comprehensive income (loss), Tax (Provision) Benefit	[2]	10
Other comprehensive income, Tax (Provision) Benefit		412	(481)
Net actuarial gain (loss) and prior service credits, Net-of-Tax Amount		(2,307)	953
Amortization of prior service credits and net actuarial gain (loss), Net-of-Tax Amount		796	845
Pension amd other postretirement benefits, Net-of-Tax Amount		(1,511)	1,798
Proportionate share of Telesat Holdco other comprehensive income (loss), Net-of-Tax Amount		(35,783)	22,033
Other comprehensive income (loss), Net-of-tax Amount		(37,294)	$ 23,831
Prior Periods [Member]
Proportionate share of Telesat Holdco other comprehensive income (loss), Before-Tax Amount		(22,056)
Proportionate share of Telesat Holdco other comprehensive income (loss), Tax (Provision) Benefit		6
Proportionate share of Telesat Holdco other comprehensive income (loss), Net-of-Tax Amount		(22,050)
Current Period [Member]
Proportionate share of Telesat Holdco other comprehensive income (loss), Before-Tax Amount		(13,737)
Proportionate share of Telesat Holdco other comprehensive income (loss), Tax (Provision) Benefit		4
Proportionate share of Telesat Holdco other comprehensive income (loss), Net-of-Tax Amount		$ (13,733)

[1] Reclassifications are included in other expenses.

[2] See Note 7, Income Taxes