Divestitures and Acquisitions Divestiture of PolyVision Division (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended		3 Months Ended		6 Months Ended
	Nov. 23, 2012	Nov. 25, 2011	Aug. 26, 2011	Nov. 23, 2012	Nov. 25, 2011	Aug. 26, 2011 PolyvisionSASandPolyvisionA/S [Member]	May 27, 2011 PolyvisionSASandPolyvisionA/S [Member]	Aug. 26, 2011 PolyvisionSASandPolyvisionA/S [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	$ 727.2	$ 719.4		$ 2,147.3	$ 2,059.3	$ 4.5	$ 4.1	$ 8.6
Gross profit	225.9	219.8		650.0	604.1	0.9	0.7	1.6
Operating income (loss)	38.4	38.2		104.5	78.6	0.3	(0.2)	0.1
Proceeds from divestiture of businesses			2.3
Restructuring costs	$ 6.0	$ 3.8		$ 14.8	$ 26.0	$ 0.9