Consolidated Statements of Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock and Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Net Income including Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2014	$ 369.0	$ 526.8	$ 292.1	$ (429.2)	$ (23.8)	$ 3.1
Increase (Decrease) in Stockholders' Equity
Net income	123.8		123.9			0.5	$ 124.4
Repurchase of common stock	(220.1)			(220.1)
Purchase of noncontrolling interest	0.0	0.7	0.0	0.0	0.0	(0.7)
Stock based compensation	7.4	7.4
Exercise of stock options	24.9	(43.1)		68.0
Tax benefit related to stock plans	0.5	0.5	0.0	0.0	0.0	0.0
Shares issued	1.0	1.0	0.0	0.0	0.0	0.0
Other comprehensive (loss) income	(49.7)				(49.8)	0.1
Ending balance at Sep. 30, 2015	257.4	491.9	416.0	(581.3)	(73.6)	4.4
Beginning balance at Dec. 31, 2015	212.5	496.7	436.3	(658.4)	(66.8)	4.7
Increase (Decrease) in Stockholders' Equity
Net income	78.5		78.8			(0.3)
Repurchase of common stock	(55.1)			(55.1)
Stock based compensation	9.2	9.2
Exercise of stock options	23.7	(16.2)		39.9
Tax benefit related to stock plans	70.4	0.0	70.4	0.0	0.0	0.0
Shares issued	0.7	0.7	0.0	0.0	0.0	0.0
Other comprehensive (loss) income	(7.5)				(10.1)	2.6
Cash dividends declared	24.1		24.1
Distribution of GCP	186.3		54.7		135.3	(3.7)
Ending balance at Sep. 30, 2016	$ 494.6	$ 490.4	$ 616.1	$ (673.6)	$ 58.4	$ 3.3