Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Aug. 31, 2014	May 31, 2014
Condensed Consolidated Balance Sheets
Accounts receivable, allowances (in dollars)	$ 6.0	$ 6.2
Property, plant and equipment, accumulated depreciation (in dollars)	420.6	424.3
Intangible assets, accumulated amortization (in dollars)	$ 38.4	$ 36.2
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	44,993,858	44,674,186
Treasury stock, shares	5,116,217	5,113,939