Supplemental Cash Flow Data (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Change in Operating Capital [Abstract]
(Increase) decrease in accounts receivable	$ 973.2	$ 779.5
(Increase) decrease in work in process and other current assets	(271.9)	(213.5)
Increase (decrease) in accounts payable	(1,522.1)	(1,117.6)
Increase (decrease) in customer advances and other current liabilities	(181.3)	39.9
Change in other assets and liabilities, net	6.0	(38.9)
Use of operating capital	(996.1)	(550.6)
Income taxes paid	83.2	64.8
Interest paid	$ 55.8	$ 53.2