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 Income (Loss) [Member]
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
Balance at Dec. 31, 2015					5,057,382
Stock issuance		118,493
Share-based employee compensation	0.6		0.6
Net earnings (loss)	(9.9)			(9.9)
Other comprehensive income	10.8					10.8
Balance at Mar. 31, 2016	770.3	$ 0.6	1,152.4	355.3	$ (261.4)	(476.6)
Balance at Mar. 31, 2016		55,477,557
Balance at Mar. 31, 2016					5,057,382
Balance at Dec. 31, 2016	$ 266.4	$ 0.6	504.9	469.9	$ (305.2)	(403.8)
Balance at Dec. 31, 2016	54,428,233	54,428,233
Balance at Dec. 31, 2016	6,168,907				6,168,907
Cumulative effect impact of ASU 2016-09 adoption	$ 8.7			8.7
Stock issuance		78,402
Share-based employee compensation	1.1		1.1
Net earnings (loss)	30.4			30.4
Separation of Armstrong Flooring, Inc.	0.9		0.9
Other comprehensive income	13.7					13.7
Acquisition of treasury stock	(50.0)	$ (50.0)			$ (50.0)
Acquisition of treasury stock, shares		(1,190,021)			1,190,021
Balance at Mar. 31, 2017	$ 271.2	$ 0.6	$ 506.9	$ 509.0	$ (355.2)	$ (390.1)
Balance at Mar. 31, 2017	53,316,614	53,316,614
Balance at Mar. 31, 2017	7,358,928				7,358,928