Consolidated Balance Sheets (Parenthetical) - $ / shares	May 31, 2019	May 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized (in thousands)	10,000	10,000
Preferred stock, shares issued (in thousands)	0	0
Preferred stock, shares outstanding (in thousands)	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized (in thousands)	75,000	75,000
Common stock, shares issued (in thousands)	22,669	22,143
Common stock, shares outstanding (in thousands)	22,669	22,143