Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Aug. 31, 2013	May 31, 2013
Condensed Consolidated Balance Sheets
Accounts receivable, allowances (in dollars)	$ 7.8	$ 8.7
Property, plant and equipment, accumulated depreciation (in dollars)	374.0	354.5
Intangible assets, accumulated amortization (in dollars)	$ 27.8	$ 25.1
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, authorized shares	250,000	250,000
Preferred stock, issued shares	0	0
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, authorized shares	100,000,000	100,000,000
Common stock, issued shares	44,689,937	44,691,437
Treasury stock, shares	5,107,851	5,309,252