Condensed Consolidated Statements Of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive (Loss) [Member]
Balance at Dec. 31, 2014	$ 649.1	$ 0.6	$ 1,134.4	$ 271.0	$ (261.4)	$ (495.5)
Balance at Dec. 31, 2014		55,126,153
Balance at Dec. 31, 2014					5,057,382
Stock issuance		176,819
Share-based employee compensation	9.9		9.9
Net earnings	76.2			76.2
Other comprehensive income	12.1					12.1
Balance at Jun. 30, 2015	747.3	$ 0.6	1,144.3	347.2	$ (261.4)	(483.4)
Balance at Jun. 30, 2015		55,302,972
Balance at Jun. 30, 2015					5,057,382
Balance at Dec. 31, 2015	$ 768.8	$ 0.6	1,151.8	365.2	$ (261.4)	(487.4)
Balance at Dec. 31, 2015	55,359,064	55,359,064
Balance at Dec. 31, 2015	5,057,382				5,057,382
Stock issuance		125,919
Share-based employee compensation	$ 7.0		7.0
Net earnings	7.0			7.0
Other comprehensive income	4.7					4.7
Separation of Armstrong Flooring, Inc.	(585.1)		(641.9)			56.8
Balance at Jun. 30, 2016	$ 202.4	$ 0.6	$ 516.9	$ 372.2	$ (261.4)	$ (425.9)
Balance at Jun. 30, 2016	55,484,983	55,484,983
Balance at Jun. 30, 2016	5,057,382				5,057,382