Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss)	Retained Earnings
Beginning Balance at May. 31, 2018	$ 560,175	$ 8,278	$ 202,572	$ (9,746)	$ 359,071
Beginning Balance (in shares) at May. 31, 2018		51,736,000
Issuance of shares under share-based compensation plan	8,473	$ 40	8,433
Issuance of shares under share-based compensation plan (in shares)		251,000
Issuance of shares under employee stock purchase plan	519	$ 2	517
Issuance of shares under employee stock purchase plan (in shares)		8,000
Net income	15,237				15,237
Other comprehensive (loss)	(2,778)			(2,778)
Ending Balance at Aug. 31, 2018	581,626	$ 8,320	211,522	(12,524)	374,308
Ending Balance (in shares) at Aug. 31, 2018		51,995,000
Beginning Balance at May. 31, 2019	$ 637,899	$ 8,355	221,937	(11,640)	419,247
Beginning Balance (in shares) at May. 31, 2019	52,216,589	52,217,000
Issuance of shares under share-based compensation plan	$ 9,713	$ 30	9,683
Issuance of shares under share-based compensation plan (in shares)		196,000
Issuance of shares under employee stock purchase plan	538	$ 2	536
Issuance of shares under employee stock purchase plan (in shares)		10,000
Net income	14,652				14,652
Other comprehensive (loss)	(2,496)			(2,496)
Ending Balance at Aug. 31, 2019	$ 660,306	$ 8,387	$ 232,156	$ (14,136)	$ 433,899
Ending Balance (in shares) at Aug. 31, 2019	52,422,942	52,423,000