Subsequent Events - Pro Forma Income Statement (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Subsequent Event [Line Items]
Net sales	$ 363.1	$ 313.0	$ 718.3	$ 615.5	$ 1,265.4
Cost of sales	262.0	221.5	520.5	442.2	914.0
Gross profit	101.1	91.5	197.8	173.3	351.4
Selling, distribution & administrative expenses	75.8	69.6	152.4	139.0	279.8
Special charges	0.0	0.2	0.0	0.2	0.3
Operating income from continuing operations	25.3	21.7	45.4	34.1	71.3
Interest and other (income) expense, net	0.0	(0.1)	0.1	(0.3)	0.5
Income from continuing operations before income taxes	25.3	21.8	45.3	34.4	70.8
Provision for income taxes	7.5	2.5	13.3	4.8	(5.3)
Net income from continuing operations	$ 17.8	$ 19.3	$ 32.0	$ 29.6	$ 76.1
Basic (in dollars per share)	$ 0.48	$ 0.52	$ 0.86	$ 0.80	$ 2.06
Diluted (in dollars per share)	$ 0.47	$ 0.52	$ 0.84	$ 0.79	$ 2.02
Basic (in shares)	37.2	37.0	37.2	37.0	37.0
Diluted (in shares)	37.9	37.4	37.9	37.3	37.6
Overhead charges, pro forma adjustment			$ 0.5		$ 0.9
Accrued professional fees, pro forma adjustment			0.7
Estimated tax, pro forma adjustment			0.1		0.3
Disposal Group, Disposed of by Sale, Not Discontinued Operations | French Business | Pro Forma
Subsequent Event [Line Items]
Net sales			443.4		791.8
Net sales, pro forma adjustment			(274.9)		(473.6)
Cost of sales			290.9		518.6
Cost of sales, pro forma adjustment			(229.6)		(395.4)
Gross profit			152.5		273.2
Gross profit, pro forma adjustment			(45.3)		(78.2)
Selling, distribution & administrative expenses			123.4		227.6
Selling, distribution & administrative expenses, pro forma adjustment			(29.0)		(52.2)
Special charges					0.3
Special charges, pro forma adjustment					0.0
Operating income from continuing operations			29.1		45.3
Operating income from continuing operations, pro forma adjustment			(16.3)		(26.0)
Interest and other (income) expense, net			0.1		0.2
Interest and other (income) expense, net, pro forma adjustment			0.0		(0.3)
Income from continuing operations before income taxes			29.0		45.1
Income from continuing operations before income taxes, pro forma adjustment			(16.3)		(25.7)
Provision for income taxes			7.2		(14.3)
Provision for income taxes, pro forma adjustment			(6.1)		(9.0)
Net income from continuing operations			21.8		59.4
Net income (loss) from continuing operations			$ (10.2)		$ (16.7)
Basic (in dollars per share)			$ 0.59		$ 1.61
Diluted (in dollars per share)			$ 0.58		$ 1.58
Basic (in shares)			37.2		37.0
Diluted (in shares)			37.9		37.6