Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Coronavirus Aid Relief and Economic Security Act, Income Tax Expense (Benefit)		$ (3,100)
Deferred tax assets	$ 27,819			$ 27,339
Accrued tax penalties	0
Unrecognized tax benefits, interest on income taxes accrued	3,600
Unrecognized tax benefits that would reduce the income tax provision	8,700
Unrecognized Tax Benefits	43,000
Forecast [Member]
Income Tax Contingency [Line Items]
Reduction to unrecognized tax benefits			$ 16,400
Telesat Canada [Member] | Federal [Member]
Income Tax Contingency [Line Items]
Fed Tax On GILTI	0			0
Deferred tax assets	$ 0			$ 0