Accumulated Other Comprehensive Loss (Components of Other Comprehensive Income and Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Loss [Abstract]
Amortization of prior service credits and net actuarial loss, Before-Tax Amount	[1]	$ 239	$ 203
Proportionate share of Telesat other comprehensive income (loss), Before-Tax Amount		(4,929)	14,448	[2]
Other comprehensive income (loss), Before-Tax Amount		(4,690)	14,651
Amortization of prior service credits and net actuarial loss, Tax (Provision) Benefit		(85)	(76)
Proportionate share of Telesat other comprehensive income (loss), Tax (Provision) Benefit		1,737	(5,416)
Other comprehensive income, Tax (Provision) Benefit		1,652	(5,492)
Amortization of prior service credits and net actuarial gain (loss), Net-of-Tax Amount		154	127
Proportionate share of Telesat other comprehensive income (loss), Net-of-Tax Amount		(3,192)	9,032
Other comprehensive income (loss), Net-of-Tax Amount		$ (3,038)	9,159
Equity method OCI previously suspended recovered			20,800
Equity method OCI previously suspended recovered, net of tax			$ 13,500

[1] Reclassifications are included in general and administrative expenses. I

[2] Includes $20.8 million ($13.5 million, net of tax) share in the equity of Telesat's other comprehensive income that we could not record in 2015 (see Note 5)