Organization and Principal Business (Narrative) (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) segment	Dec. 31, 2020	Mar. 31, 2020 USD ($)
Organization And Principal Business [Line Items]
Number of operating segment | segment	1
Telesat Canada [Member]
Organization And Principal Business [Line Items]
Economic interest in affiliate	62.60%	62.60%
Voting interest in affiliate	32.60%	32.60%
Common Control Reorganization [Member] | Other Expense [Member]
Organization And Principal Business [Line Items]
Transaction expenses	$ 2,300,000		$ 1,400,000
Common Control Reorganization [Member] | Plan [Member] | Public Sector Pension Investment Board [Member]
Organization And Principal Business [Line Items]
Loss contingency, contract breach	40,000,000
Common Control Reorganization [Member] | Plan [Member] | Minimum [Member] | Red Isle Private Investments Inc. [Member]
Organization And Principal Business [Line Items]
Loss contingency, contract termination	6,550,000
Common Control Reorganization [Member] | Plan [Member] | Maximum [Member] | Red Isle Private Investments Inc. [Member]
Organization And Principal Business [Line Items]
Loss contingency, contract termination	$ 22,910,000