Foreign Exchange (Details) $ in Thousands, $ in Millions	12 Months Ended
Dec. 31, 2020 CAD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 CAD ($)
Effects Of Changes In Foreign Exchange Rates [Line Items]
Adjustments for unrealised foreign exchange losses (gains)	$ (9,232)		$ 62,753
Realized foreign exchange (gain) loss	(544)		966
Foreign exchange loss (gain)	8,688		(61,787)
Intercompany notes		$ 751.0
Unrealized foreign exchange loss - intercompany notes
Effects Of Changes In Foreign Exchange Rates [Line Items]
Adjustments for unrealised foreign exchange losses (gains)	31,617		0
Unrealized foreign exchange gain - long-term notes
Effects Of Changes In Foreign Exchange Rates [Line Items]
Adjustments for unrealised foreign exchange losses (gains)	$ (22,385)		$ (62,753)

The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2020-01-01
-Section A Statement of cash flows for an entity other than a financial institution
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&doctype=Illustrative%20Examples&dita_xref=IAS07_IE_A_TI
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2020-01-01
-Paragraph 52
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=21&code=ifrs-tx-2020-en-r&anchor=para_52_a&doctype=Standard
-URIDate 2020-01-01

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Balance Type:	credit
Period Type:	duration