Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Feb. 28, 2013	May 31, 2012
Condensed Consolidated Balance Sheets
Accounts receivable, allowances (in dollars)	$ 6.7	$ 8.2
Property, plant and equipment, accumulated depreciation (in dollars)	340.0	298.4
Intangible assets, accumulated amortization (in dollars)	$ 43.6	$ 34.1
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	44,703,137	44,849,196
Treasury stock, shares	4,969,742	4,576,368