Accounts Receivable (Summary of Reserve for Discounts and Allowances) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Provision for discounts and doubtful accounts
As at January 1,	$ 55.8	$ 48.5
Provision charged to operations	569.9	293.8
Payments/credits related to sales	(498.3)	(286.6)
As at September 30,	$ 127.4	$ 55.7