Stock-Based Compensation - Summary of Non-Vested Stock Option Awards (Detail) - $ / shares shares in Thousands	12 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017
Number of Stock Options
Non-vested, beginning of year	219
Granted	96	90	111
Vested	(103)
Forfeited	(54)
Non-vested, end of year	158	219
Weighted Average Grant Date Fair Value Per Share
Non-vested, beginning of year	$ 11.55
Granted	12.55
Vested	10.75
Forfeited	12.70
Non-vested, end of year	$ 12.26	$ 11.55