Consolidated Balance Sheets (Parenthetical) - $ / shares	May 31, 2020	May 31, 2019
Stockholders' equity
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	600,000,000.0	600,000,000.0
Common stock, shares issued	358,800,000	359,300,000
Common stock, shares outstanding	358,800,000	359,300,000