Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Accumulated other comprehensive income (loss), beginning balance			$ (28,698)
Net current-period other comprehensive income (loss)	$ 417	$ 1,128	9,576	$ 1,362
Accumulated other comprehensive income (loss), ending balance	(19,122)		(19,122)		$ (28,698)
Postretirement Benefits [Member]
Accumulated other comprehensive income (loss), beginning balance			(13,459)	(13,982)	(13,982)
Other comprehensive income (loss) before reclassification					(265)
Amounts reclassified from accumulated other comprehensive income (loss)			285		788
Net current-period other comprehensive income (loss)			285		523
Accumulated other comprehensive income (loss), ending balance	(13,174)		(13,174)		(13,459)
Proportionate Share of Telesat Other Comprehensive Loss [Member]
Accumulated other comprehensive income (loss), beginning balance			(15,239)	(15,239)	(15,239)
Other comprehensive income (loss) before reclassification			9,291
Amounts reclassified from accumulated other comprehensive income (loss)
Net current-period other comprehensive income (loss)			9,291
Accumulated other comprehensive income (loss), ending balance	(5,948)		(5,948)		(15,239)
Accumulated Other Comprehensive Loss [Member]
Accumulated other comprehensive income (loss), beginning balance			(28,698)	$ (29,221)	(29,221)
Other comprehensive income (loss) before reclassification			9,291		(265)
Amounts reclassified from accumulated other comprehensive income (loss)			285		788
Net current-period other comprehensive income (loss)			9,576		523
Accumulated other comprehensive income (loss), ending balance	$ (19,122)		$ (19,122)		$ (28,698)