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
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	38.8		39.2			(0.4)
Repurchase of common stock	(35.1)			(35.1)
Stock based compensation	6.5	6.5
Exercise of stock options	19.3	(10.5)		29.8
Tax benefit related to stock plans	72.3		72.3
Shares issued	0.7	0.7	0.0	0.0	0.0	0.0
Other comprehensive (loss) income	(5.5)				(8.1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	(2.6)
Cash dividends declared	(12.0)		(12.0)
Distribution of GCP	191.5		59.9		135.3	(3.7)
Ending balance at Jun. 30, 2016	489.0	493.4	595.7	(663.7)	60.4	3.2
Beginning balance at Dec. 31, 2016	372.4	488.0	619.3	(804.9)	66.4	3.6
Increase (Decrease) in Stockholders' Equity
Net income	86.4		86.8			(0.4)
Repurchase of common stock	(30.0)			(30.0)
Payments to taxing authorities in consideration of employee tax obligations relative to stock-based compensation arrangements	(2.4)	(2.4)
Stock based compensation	5.4	5.4
Exercise of stock options	11.8	(17.0)		28.8
Shares issued	0.7	0.7	0.0	0.0	0.0	0.0
Other comprehensive (loss) income	(9.9)				(9.9)
Dividends declared	28.8		28.8
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	0.0
Ending balance at Jun. 30, 2017	$ 405.6	$ 474.7	$ 677.3	$ (806.1)	$ 56.5	$ 3.2