Number of shares that have been repurchased and retired during the period.

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Name:	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Stock Purchase - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2019	May 31, 2018	Aug. 31, 2018	Dec. 31, 2008
Stock Repurchase Program [Line Items]
Shares authorized to purchase				1,500,000
Cumulative number of shares repurchased			149,368
Cost of repurchased shares, including commissions			$ 923
Number of shares repurchased		0
During Fiscal 2019
Stock Repurchase Program [Line Items]
Number of shares repurchased	0