Consolidated and Combined Statement of Stockholder's Equity (unaudited) - USD ($) $ in Millions	Total		Former Parent's Net Investment	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance at Dec. 31, 2017	$ 1,407.9		$ 1,427.7	$ 0.0	$ 0.0	$ 0.0	$ (19.8)	$ 0.0
Beginning balance, shares at Dec. 31, 2017				0				0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adopting new accounting standard	(4.0)		(4.0)
Net income	44.8		44.8
Other comprehensive income (loss)	0.5						0.5
Net transfers from parent and affiliates	(59.1)		(59.1)
Share-based Compensation	4.8		4.8
Dividends paid to common shareholders	0.0
Restricted shares, net - value	4.8
Ending balance at Jun. 30, 2018	1,394.9		1,414.2	$ 0.0	0.0	0.0	(19.3)	$ 0.0
Ending balance, shares at Jun. 30, 2018				0				0
Beginning balance at Mar. 31, 2018	1,372.4		1,391.9	$ 0.0	0.0	0.0	(19.5)	$ 0.0
Beginning balance, shares at Mar. 31, 2018				0				0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	22.6		22.6
Other comprehensive income (loss)	0.2						0.2
Net transfers from parent and affiliates	(2.9)		(2.9)
Restricted shares, net - value	2.6		2.6
Ending balance at Jun. 30, 2018	1,394.9		1,414.2	$ 0.0	0.0	0.0	(19.3)	$ 0.0
Ending balance, shares at Jun. 30, 2018				0				0
Beginning balance at Dec. 31, 2018	1,684.5		0.0	$ 0.5	1,685.7	19.5	(17.7)	$ (3.5)
Beginning balance, shares at Dec. 31, 2018				48,800,000				(100,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	59.5					59.5
Other comprehensive income (loss)	(2.3)						(2.3)
Share-based Compensation	7.1
Dividends paid to common shareholders	(5.0)					(5.0)
Restricted shares, net - shares				200,000				(200,000)
Restricted shares, net - value	$ 2.9				7.8			$ (4.9)
Shares repurchased, shares	269,574							(300,000)
Shares repurchased	$ (8.0)							$ (8.0)
Retirement of treasury stock - shares				(600,000)				600,000
Retirement of treasury stock - value					(16.4)			$ 16.4
Stockholders' equity, other	2.7				2.7
Ending balance at Jun. 30, 2019	1,734.3	[1]	0.0	$ 0.5	1,679.8	74.0	(20.0)	$ 0.0
Ending balance, shares at Jun. 30, 2019				48,400,000				0
Beginning balance at Mar. 31, 2019	1,705.2		0.0	$ 0.5	1,690.2	44.7	(18.3)	$ (11.9)
Beginning balance, shares at Mar. 31, 2019				48,800,000				(400,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31.8					31.8
Other comprehensive income (loss)	(1.7)						(1.7)
Dividends paid to common shareholders	(2.5)					(2.5)
Restricted shares, net - shares				200,000				(200,000)
Restricted shares, net - value	(0.3)				4.2			$ (4.5)
Shares repurchased, shares								0
Shares repurchased	0.0							$ 0.0
Retirement of treasury stock - shares				(600,000)				600,000
Retirement of treasury stock - value					(16.4)			$ 16.4
Stockholders' equity, other	1.8				1.8
Ending balance at Jun. 30, 2019	$ 1,734.3	[1]	$ 0.0	$ 0.5	$ 1,679.8	$ 74.0	$ (20.0)	$ 0.0
Ending balance, shares at Jun. 30, 2019				48,400,000				0

[1] Unaudited