Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Consolidated Statements Of Comprehensive Income (Loss) [Abstract]
Net income	$ 93,093	$ 89,755
Pension and other post-retirement benefits	(2,826)	(1,511)
Proportionate share of Telesat other comprehensive income (loss)	(14,232)	(35,783)
Other comprehensive income (loss), Net-of-tax Amount	(17,058)	(37,294)
Comprehensive income (loss)	$ 76,035	$ 52,461