Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Nov. 30, 2015	May. 31, 2015
Condensed Consolidated Balance Sheets
Accounts receivable, allowances (in dollars)	$ 4.7	$ 5.8
Property, plant and equipment, accumulated depreciation (in dollars)	420.7	398.5
Intangible assets, accumulated amortization (in dollars)	$ 24.5	$ 22.5
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	45,039,798	44,895,934
Treasury stock, shares	9,996,173	9,473,058