Related Party Transactions (Narrative) (Details) - USD ($)		1 Months Ended	3 Months Ended			6 Months Ended		9 Months Ended		12 Months Ended
	Jul. 02, 2020	Apr. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2013	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jul. 01, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Due to affiliate			$ 106,000					$ 106,000		$ 98,000
Amounts due under the transaction			17,000					$ 17,000		$ 88,000
Transaction, Consulting Agreement [Member] | Director [Member]
Related Party Transaction [Line Items]
Related party transaction, expiration date								Dec. 14, 2012
Transaction fee			360,000	$ 360,000				$ 1,080,000	$ 1,080,000
Transaction income during the period			$ 11,250	11,250				33,750	$ 33,750
Monthly Fee [Member] | Transaction, Consulting Agreement [Member] | Director [Member]
Related Party Transaction [Line Items]
Transaction fee								$ 120,000
Telesat Canada [Member]
Related Party Transaction [Line Items]
Economic interest in affiliate			62.60%					62.60%		62.60%
Voting interest in affiliate			32.60%					32.60%		32.60%
Common stock, percentage acquired by an unaffiliated third party								90.00%
Duration for shares to be paid, days								10 days
Number of stock options cancelled		6,197,776
Telesat Canada [Member] | Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Number of stock options cancelled		220,000
Telesat Canada [Member] | Transaction, Consulting Agreement [Member]
Related Party Transaction [Line Items]
Related party transaction, expiration date								Oct. 31, 2007
Consulting agreement term								initial term of seven-years
Transaction income during the period				1,250,000		$ 3,800,000	$ 3,800,000
Transaction payments received during the period						$ 3,600,000	$ 3,600,000
Telesat Canada [Member] | Annual Fee [Member] | Transaction, Consulting Agreement [Member]
Related Party Transaction [Line Items]
Transaction fee				$ 5,000,000.0
Telesat Canada [Member] | Annual Fee [Member] | Transaction Participation In Welfare Plans Administrative Fee [Member]
Related Party Transaction [Line Items]
Due to affiliate										$ 100,000
Transaction fee								$ 100,000
Telesat Canada [Member] | Years 2003 to 2006 [Member] | Brazil [Member]
Related Party Transaction [Line Items]
Tax assessment imposed audit								$ 600,000
XTAR, LLC [Member]
Related Party Transaction [Line Items]
Percentage of ownership interest			56.00%					56.00%
Management fee charged as a percentage of revenue					3.70%
XTAR, LLC [Member] | Transaction, Management Agreement [Member]
Related Party Transaction [Line Items]
Due from affiliates			$ 100,000					$ 100,000		$ 100,000
Amount due to Loral under the Loral Management Agreement											$ 6,600,000	$ 6,600,000
Increase (decrease) in due from affiliates	$ (5,900,000)
Allowance for doubtful receivable											$ 6,600,000
Common Control Reorganization [Member] | Plan [Member]
Related Party Transaction [Line Items]
Counterparties indemnifying								Loral, Telesat Corporation and Telesat CanHoldco
Counterparty indemnified								Public Sector Pension Investment Board
Tax indemnification - maximum			$ 50,000,000					$ 50,000,000
Series B Preferred Stock [Member]
Related Party Transaction [Line Items]
Preferred stock, shares issued			5					5		5
Red Isle Private Investments Inc. [Member] | Common Control Reorganization [Member] | Plan [Member]
Related Party Transaction [Line Items]
Related party transaction, description of transaction								if such payment is less than $7 million due to a lack of available cash, Telesat Partnership will be required to pay the balance of such unpaid amount to Red Isle no later than 35 trading days following consummation of the Transaction.
Transaction fee								$ 7,000,000
Red Isle Private Investments Inc. [Member] | Minimum [Member] | Common Control Reorganization [Member] | Plan [Member]
Related Party Transaction [Line Items]
Loss contingency, contract termination			$ 6,550,000					6,550,000
Red Isle Private Investments Inc. [Member] | Maximum [Member] | Common Control Reorganization [Member] | Plan [Member]
Related Party Transaction [Line Items]
Loss contingency, contract termination			22,910,000					22,910,000
Public Sector Pension Investment Board [Member] | Common Control Reorganization [Member] | Plan [Member]
Related Party Transaction [Line Items]
Loss contingency, contract breach			$ 40,000,000.0					$ 40,000,000.0
MHR Funds [Member]
Related Party Transaction [Line Items]
Percentage of outstanding voting common stock								39.90%		39.90%
Percentage of combined ownership of voting and non-voting common stock			58.40%					58.40%		58.40%
MHR Funds [Member] | Maximum [Member] | Additional Voting Common Stock [Member]
Related Party Transaction [Line Items]
Percentage of outstanding voting common stock								6.00%