Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Feb. 29, 2020	May 31, 2019
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowances	$ 58,492	$ 54,748
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized	50,000,000	50,000,000
Preferred stock, issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	300,000,000	300,000,000
Common stock, issued	143,220,000	142,439,000
Common stock, outstanding	129,879,000	130,995,000