Other Income and Expense Footnotes (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 CAD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 CAD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CAD ($)	Dec. 31, 2017 USD ($)
Other income and expense [Line Items]
Nonoperating Income (Expense)		$ (284.5)		$ (272.0)		$ (294.5)
Affiliated Entity [Member] | Release of guarantee obligations [Member]
Other income and expense [Line Items]
Nonoperating Income (Expense)			$ 5.8	$ 4.3
Affiliated Entity [Member] | Acquisition purchase price adjustment settlement gain [Member]
Other income and expense [Line Items]
Nonoperating Income (Expense)	$ 2.0	$ 1.5			$ 10.9	$ 8.3