Consolidated Balance Sheets (Parenthetical) - $ / shares	May 31, 2016	May 31, 2015
Stockholders' equity
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	360,400,000	361,200,000
Common stock, shares outstanding	360,400,000	361,200,000