Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Accumulated other comprehensive income (loss), beginning balance			$ (29,221)
Net current-period other comprehensive income (loss)	$ (698)	$ 1,543	664	$ 2,592
Accumulated other comprehensive income (loss), ending balance	(28,557)		(28,557)		$ (29,221)
Postretirement Benefits [Member]
Accumulated other comprehensive income (loss), beginning balance			(13,982)	(9,171)	(9,171)
Other comprehensive income (loss) before reclassification					(5,147)
Amounts reclassified from accumulated other comprehensive income (loss)			664		336
Net current-period other comprehensive income (loss)			664		(4,811)
Accumulated other comprehensive income (loss), ending balance	(13,318)		(13,318)		(13,982)
Proportionate Share of Telesat Other Comprehensive Loss [Member]
Accumulated other comprehensive income (loss), beginning balance			$ (15,239)	(11,745)	(11,745)
Other comprehensive income (loss) before reclassification					$ (3,494)
Amounts reclassified from accumulated other comprehensive income (loss)
Net current-period other comprehensive income (loss)					$ (3,494)
Accumulated other comprehensive income (loss), ending balance	(15,239)		$ (15,239)		(15,239)
Accumulated Other Comprehensive Loss [Member]
Accumulated other comprehensive income (loss), beginning balance			(29,221)	$ (20,916)	(20,916)
Other comprehensive income (loss) before reclassification					(8,641)
Amounts reclassified from accumulated other comprehensive income (loss)			664		336
Net current-period other comprehensive income (loss)			664		(8,305)
Accumulated other comprehensive income (loss), ending balance	$ (28,557)		$ (28,557)		$ (29,221)