Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Postretirement Benefits [Member]	Dec. 31, 2013 Postretirement Benefits [Member]	Mar. 31, 2014 Proportionate Share of Telesat Other Comprehensive Loss [Member]	Dec. 31, 2013 Proportionate Share of Telesat Other Comprehensive Loss [Member]	Mar. 31, 2014 Accumulated Other Comprehensive Loss [Member]	Dec. 31, 2013 Accumulated Other Comprehensive Loss [Member]
Accumulated other comprehensive income (loss), beginning balance	$ (20,916)		$ (9,171)	$ (17,653)	$ (11,745)	$ (19,741)	$ (20,916)	$ (37,394)
Other comprehensive income (loss) before reclassification				3,102	699	7,996	699	11,098
Amounts reclassified from accumulated other comprehensive income (loss)			64	5,380			64	5,380
Net current-period other comprehensive income (loss)	763	1,372	64	8,482	699	7,996	763	16,478
Accumulated other comprehensive income (loss), ending balance	$ (20,153)		$ (9,107)	$ (9,171)	$ (11,046)	$ (11,745)	$ (20,153)	$ (20,916)