Condensed Consolidated Statement of Changes in Stockholder's Equity - 6 months ended Jun. 30, 2018 - USD ($) $ in Millions	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income, net	Redeemable Noncontrolling Interests	Total
Beginning balance at Dec. 31, 2017	$ 1.2	$ (558.3)	$ 2,623.7	$ 993.3	$ 50.7	$ 9.4	$ 3,110.6
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock of $0.27 per share				(61.0)			(61.0)
Stock-based compensation			21.0				21.0
Common stock repurchased from employee stock plans		(15.8)	1.4				(14.4)
Purchase of common stock		(91.8)					(91.8)
Net income excluding noncontrolling interest				201.7			201.7
Other comprehensive income					(16.5)		(16.5)
Net loss attributable to redeemable noncontrolling interest				0.6		(0.6)	0.6
Redemption value adjustment of redeemable noncontrolling interest				(0.6)		0.6	(0.6)
Ending balance at Jun. 30, 2018	$ 1.2	$ (665.9)	$ 2,646.1	$ 1,134.0	$ 34.2	$ 9.4	$ 3,149.6