Discontinued Operations (Schedule of Business Details and Line Items Comprising Discontinued Operations on Statements of Earnings and Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net sales	$ 115.5	$ 112.7	$ 319.1	$ 331.7
Cost of goods sold	86.8	87.1	245.7	252.2
Gross profit	28.7	25.6	73.4	79.5
Selling, general and administrative expenses	20.4	20.2	61.6	61.9
Operating income	8.3	5.4	11.8	17.6
Interest expense		0.4		1.3
Other non-operating expense, net	1.0	0.5	1.6	0.7
Earnings from discontinued operations before income tax	7.3	4.5	10.2	15.6
Income tax expense	2.5	(0.5)	7.2	1.2
Net earnings from discontinued operations, net of tax	4.8	5.0	3.0	14.4
(Loss) gain from disposal of discontinued businesses, before income tax	(27.3)	2.4	(31.9)	(21.0)
Income tax (benefit)	(5.0)	(4.6)	(4.9)	(4.9)
(Loss) gain from disposal of discontinued businesses, net of tax	(22.3)	7.0	(27.0)	(16.1)
Net (loss) gain from discontinued operations	(17.5)	12.0	(24.0)	(1.7)
EMEA and Pacific Rim Business [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net sales	115.5	112.7	319.1	331.7
Cost of goods sold	86.8	87.1	245.7	252.2
Gross profit	28.7	25.6	73.4	79.5
Selling, general and administrative expenses	20.4	20.2	61.6	61.9
Operating income	8.3	5.4	11.8	17.6
Interest expense		0.4		1.3
Other non-operating expense, net	1.0	0.5	1.6	0.7
Earnings from discontinued operations before income tax	7.3	4.5	10.2	15.6
Income tax expense	2.5	(0.5)	7.2	1.2
Net earnings from discontinued operations, net of tax	4.8	5.0	3.0	14.4
(Loss) gain from disposal of discontinued businesses, before income tax	(27.3)	2.4	(31.9)	(21.0)
(Loss) gain from disposal of discontinued businesses, net of tax	(27.3)	2.4	(31.9)	(21.0)	$ (19.3)	$ (74.0)
Net (loss) gain from discontinued operations	(22.5)	7.4	(28.9)	(6.6)
Flooring Businesses [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income tax (benefit)	(5.0)	(4.6)	(4.9)	(4.9)
(Loss) gain from disposal of discontinued businesses, net of tax	5.0	4.6	4.9	4.9
Net (loss) gain from discontinued operations	$ 5.0	$ 4.6	$ 4.9	$ 4.9