Nature Of Operations (Schedule Of Segment Reporting Information) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Net sales to external customers	$ 2,515.3		$ 2,527.4		$ 2,428.7
Equity (earnings) from joint venture	(65.1)		(59.4)		(55.9)
Segment operating income (loss)	239.1		265.6		284.9
Segment assets	2,606.2		2,916.6
Depreciation and amortization	123.4	[1]
Asset impairment	15.8	[1]			5.2
Investment in joint venture	129.0		132.0	[1]	133.5
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Segment assets			2,722.0	[2]	2,672.7	[2]
Depreciation and amortization			102.5		105.0	[1]
Asset impairment					5.2
Purchases of property, plant and equipment	217.1	[1]	209.0		187.2
Building Products [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	1,294.3		1,264.6		1,218.9
Equity (earnings) from joint venture	(65.1)		(59.4)		(55.9)
Segment operating income (loss)	264.7		263.1		230.4
Segment assets	1,079.7
Depreciation and amortization	66.0	[1]
Asset impairment	0.4	[1]
Investment in joint venture	129.0		132.0	[1]	133.5
Building Products [Member] | Continuing Operations [Member]
Segment Reporting Information [Line Items]
Segment assets			1,071.9	[2]	975.1	[2]
Depreciation and amortization			56.3		62.2	[1]
Asset impairment					4.6
Purchases of property, plant and equipment	128.1	[1]	134.5		98.5
Resilient Flooring [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	712.9		728.8		749.2
Segment operating income (loss)	61.6		69.8		70.3
Segment assets	492.7
Depreciation and amortization	29.6	[1]
Resilient Flooring [Member] | Continuing Operations [Member]
Segment Reporting Information [Line Items]
Segment assets			462.9	[2]	445.6	[2]
Depreciation and amortization			25.8		22.7	[1]
Purchases of property, plant and equipment	51.6	[1]	50.7		65.1
Wood Flooring [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	508.1		534.0		460.6
Segment operating income (loss)	(14.9)		6.0		37.3
Segment assets	329.8
Depreciation and amortization	16.5	[1]
Asset impairment	15.4	[1]
Wood Flooring [Member] | Continuing Operations [Member]
Segment Reporting Information [Line Items]
Segment assets			335.2	[2]	326.4	[2]
Depreciation and amortization			11.4		11.1	[1]
Asset impairment					0.6
Purchases of property, plant and equipment	26.0	[1]	8.0		14.4
Unallocated Corporate [Member]
Segment Reporting Information [Line Items]
Segment operating income (loss)	(72.3)		(73.3)		(53.1)
Segment assets	704.0
Depreciation and amortization	11.3	[1]
Unallocated Corporate [Member] | Continuing Operations [Member]
Segment Reporting Information [Line Items]
Segment assets			852.0	[2]	925.6	[2]
Depreciation and amortization			9.0		9.0	[1]
Purchases of property, plant and equipment	$ 11.4	[1]	$ 15.8		$ 9.2

[1] Totals for 2014, 2013 and 2012 will differ from the totals on our Consolidated Statement of Cash Flow by the amounts that have been classified as discontinued operations

[2] Totals for 2013 and 2012 will differ from the totals on our Consolidated Balance Sheet by the amounts that have been classified as deconsolidated operations