Unaudited Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Aug. 31, 2019	May 31, 2019	Aug. 31, 2018	May 31, 2018
Statement Of Stockholders Equity [Abstract]
Deferred tax adjusted to pension	$ 74	$ 78	$ 82	$ 87
Dividends paid per share	$ 0.225	$ 0.225	$ 0.225	$ 0.20

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
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