Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2015	[1]	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements Of Comprehensive Income (Loss) [Abstract]
Net income (loss)	$ (12,146)		$ (3,892)		$ 32,552		$ 30,686		$ (1,885)		$ (3,555)		$ 17,800		$ (82,642)		$ 47,200		$ (70,282)	$ (25,829)
Post-retirement benefits																	(615)		523	(4,811)
Proportionate share of Telesat other comprehensive income (loss)																	15,477	[2]		(3,494)
Other comprehensive income (loss), Net-of-Tax Amount																	14,862		523	(8,305)
Comprehensive (loss) income																	$ 62,062		$ (69,759)	$ (34,134)

[1] The quarterly earnings per share information is computed separately for each period. Therefore, the sum of such quarterly per share amounts may differ from the total for the year.

[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 6)