Other Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1],[2]	Sep. 30, 2017	[1],[2]	Jun. 30, 2017	[1],[2]	Mar. 31, 2017	[1],[2]	Dec. 31, 2016	[1],[2]	Sep. 30, 2016	[1],[2]	Jun. 30, 2016	[1],[2]	Mar. 31, 2016	[1],[2]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Nonoperating Income (Expense) [Abstract]
Net losses on sales of businesses																	$ (24.1)	$ (41.4)	$ (50.0)
Other																	(2.1)	1.1	0.4
Total other expense, net	$ (1.7)		$ (9.9)		$ (15.4)		$ 0.8		$ (26.8)		$ 5.3		$ 0.4		$ (19.2)		$ (26.2)	$ (40.3)	$ (49.6)

[1] As part of the adoption of FASB ASU 2017-07, we have reclassified a portion of postretirement costs from salaries and related expenses to other income (expense), net.

[2] The three months ended June 30 and September 30, 2017 included pre-tax net losses of $13.1 and $8.7, respectively, on sales of businesses. The three months ended March 31 and December 31, 2016 included pre-tax net losses of $16.3 and $25.3, respectively, on sales of businesses.