Other Income and Expense Footnotes (Details) CAD in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2017 CAD	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Other income and expense [Line Items]
Nonoperating Income (Expense)	$ (343.4)		$ (274.1)	$ (111.1)
Affiliated Entity [Member] | Purchase Price Adjustment [Member]
Other income and expense [Line Items]
Nonoperating Income (Expense)	$ 8.3	CAD 10.9