Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital (Deficit)	Retained Earnings	Net Parent Company Investment	Accumulated Other Comprehensive (Loss) Income	Treasury Stock
Common stock, outstanding beginning of period (in shares) at Dec. 31, 2014		0
Beginning balance at Dec. 31, 2014	$ 1,251.4	$ 0.0	$ 0.0	$ 0.0	$ 1,272.1	$ (20.7)	$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	157.1				157.1
Other comprehensive income	(23.8)					(23.8)
Net decrease in parent company investment	(176.0)				(176.0)
Common stock, outstanding end of period (in shares) at Dec. 31, 2015		0
Ending balance at Dec. 31, 2015	1,208.7	$ 0.0	0.0	0.0	1,253.2	(44.5)	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	79.5			64.2	15.3
Other comprehensive income	1.1					1.1
Net decrease in parent company investment	(1,362.0)				(1,362.0)
Separation related adjustments	(1.0)				(1.0)
Reclassification of net investment to additional paid-in capital	0.0		(94.5)		94.5
Issuance of common stock at Spin-Off (in shares)		137,016,712
Issuance of common stock at Spin-Off	0.0	$ 1.4	(1.4)
Issuance of common stock, equity-based compensation plans (in shares)		1,584,615
Issuance of common stock, stock-based compensation plans	16.2		16.2
Stock-based compensation expense	6.3		6.3
Adjustments in connection with the Spin-Off	$ 7.7		1.4	6.3
Common stock, outstanding end of period (in shares) at Dec. 31, 2016	138,562,016	138,601,327
Ending balance at Dec. 31, 2016	$ (43.5)	$ 1.4	(72.0)	70.5	0.0	(43.4)	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	134.0
Other comprehensive income	11.4					11.4
Issuance of common stock, equity-based compensation plans (in shares)		890,533
Issuance of common stock, stock-based compensation plans	4.8		4.8
Stock-based compensation expense	11.1		11.1
Adjustments in connection with the Spin-Off	(7.2)		(7.2)
Value of shares in deferred compensation plan	$ (0.2)						(0.2)
Common stock, outstanding end of period (in shares) at Dec. 31, 2017	138,491,860	139,491,860.00000
Ending balance at Dec. 31, 2017	$ 110.4	$ 1.4	$ (63.3)	$ 204.5	$ 0.0	$ (32.0)	$ (0.2)