Accumulated Other Comprehensive Loss (Components of Other Comprehensive Income and Related Tax Effects) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Loss [Abstract]
Amortization of prior service credits and net actuarial loss, Before-Tax Amount	[1]	$ 274	$ 255	$ 513	$ 458
Proportionate share of Telesat other comprehensive income (loss), Before-Tax Amount			494	(4,929)	14,942	[2]
Other comprehensive income (loss), Before-Tax Amount		274	749	(4,416)	15,400
Amortization of prior service credits and net actuarial loss, Tax (Provision) Benefit		(95)	(97)	(180)	(173)
Proportionate share of Telesat other comprehensive income (loss), Tax (Provision) Benefit			(235)	1,737	(5,651)
Other comprehensive income, Tax (Provision) Benefit		(95)	(332)	1,557	(5,824)
Amortization of prior service credits and net actuarial gain (loss), Net-of-Tax Amount		179	158	333	285
Proportionate share of Telesat other comprehensive income (loss), Net-of-Tax Amount			259	(3,192)	9,291
Other comprehensive income (loss), Net-of-Tax Amount		$ 179	$ 417	$ (2,859)	9,576
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.

[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)