Accumulated Other Comprehensive Income (Loss) (Components of Other Comprehensive Income and Related Tax Effects) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017
Accumulated Other Comprehensive Loss [Abstract]
Net actuarial gain (loss) and prior service credits, Before-Tax Amount		$ 1,208		$ (2,101)
Amortization of prior service credits and net actuarial loss, Before-Tax Amount	[1]	1,071		1,033
Postretirement benefits, Before-Tax Amount		2,279		(1,068)
Proportionate share of Telesat Holdco other comprehensive income (loss), Before-Tax Amount		22,033		(28,132)
Other comprehensive income (loss), Before-Tax Amount		24,312		(29,200)
Net actuarial gain (loss) and prior service credits, Tax (Provision) Benefit		(255)		736
Amortization of prior service credits and net actuarial loss, Tax (Provision) Benefit		(226)		(362)
Post retirement benefits, Tax (Provision) Benefit		(481)		374
Proportionate share of Telesat Holdco other comprehensive income (loss), Tax (Provision) Benefit			[2]	9,852
Other comprehensive income, Tax (Provision) Benefit		(481)		10,226
Net actuarial gain (loss) and prior service credits, Net-of-Tax Amount		953		(1,365)
Amortization of prior service credits and net actuarial gain (loss), Net-of-Tax Amount		845		671
Postretirement benefits, Net- of-Tax		1,798		(694)
Proportionate share of Telesat Holdco other comprehensive income (loss), Net-of-Tax Amount		22,033		(18,280)
Other comprehensive income (loss), Net-of-tax Amount		$ 23,831		$ (18,974)

[1] Reclassifications are included in other expenses.

[2] See Note 7, Income Taxes