Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Feb. 29, 2016	May. 31, 2015
Condensed Consolidated Balance Sheets
Accounts receivable, allowances (in dollars)	$ 3.9	$ 5.8
Property, plant and equipment, accumulated depreciation (in dollars)	435.3	398.5
Intangible assets, accumulated amortization (in dollars)	$ 24.9	$ 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	45,050,881	44,895,934
Treasury stock, shares	10,302,570	9,473,058