Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Feb. 28, 2017	May 31, 2016
Condensed Consolidated Balance Sheets
Accounts receivable, allowances (in dollars)	$ 5.3	$ 3.9
Property, plant and equipment, accumulated depreciation (in dollars)	437.1	437.7
Intangible assets, accumulated amortization (in dollars)	$ 28.4	$ 26.5
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	45,169,677	44,867,703
Treasury stock, shares	10,845,526	10,353,153