Restructuring - Restructuring Reserve Activity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring and Related Activities [Abstract]
Balance at January 1	$ 54.0	$ 89.9
Liabilities incurred	3.9	12.9
Liabilities paid/settled	(10.2)	(27.2)
Balance at March 31	$ 47.7	$ 75.6