Changes in Equity - Summary of Changes in Equity by Component and in Total (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Nov. 30, 2019	Aug. 31, 2019	Nov. 30, 2018	Aug. 31, 2018	Nov. 30, 2019	Nov. 30, 2018
Balance	$ 907,442	$ 948,394	$ 1,037,374	$ 1,036,375	$ 948,394	$ 1,036,375
Net earnings (loss)	56,922	(2,455)	37,792	56,958
Other comprehensive income (loss)	9,970	3,156	(11,300)	(5,762)	13,126	(17,062)
Common shares issued, net of withholding tax	(3,811)	(3,213)	(658)	(4,091)
Common shares in NQ plans	239	74	306	152
Stock-based compensation	2,880	4,545	3,730	4,838
Purchases and retirement of common shares		(29,599)	(63,581)	(36,852)
Cash dividends declared	(13,446)	(13,460)	(13,401)	(13,668)
Dividends to noncontrolling interest	(1,453)		(4,007)	(2,320)
Balance	958,743	907,442	986,255	1,037,374	958,743	986,255
Accounting Standards Update 2014-09
ASC 606 transition adjustment				1,744
Additional Paid-in Capital
Balance	280,769	283,177	292,488	295,592	283,177	295,592
Net earnings (loss)	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Common shares issued, net of withholding tax	(3,811)	(3,213)	(658)	(4,091)
Common shares in NQ plans	239	74	306	152
Stock-based compensation	2,880	4,545	3,730	4,838
Purchases and retirement of common shares		(3,814)	(7,540)	(4,003)
Cash dividends declared	0	0	0	0
Dividends to noncontrolling interest	0		0	0
Balance	280,077	280,769	288,326	292,488	280,077	288,326
Additional Paid-in Capital | Accounting Standards Update 2014-09
ASC 606 transition adjustment				0
AOCI Attributable to Parent
Balance	(40,308)	(43,464)	(20,325)	(14,580)	(43,464)	(14,580)
Net earnings (loss)	0	0	0	0
Other comprehensive income (loss)	9,970	3,156	(11,245)	(5,745)
Common shares issued, net of withholding tax	0	0	0	0
Common shares in NQ plans	0	0	0	0
Stock-based compensation	0	0	0	0
Purchases and retirement of common shares		0	0	0
Cash dividends declared	0	0	0	0
Dividends to noncontrolling interest	0		0	0
Balance	(30,338)	(40,308)	(31,570)	(20,325)	(30,338)	(31,570)
AOCI Attributable to Parent | Accounting Standards Update 2014-09
ASC 606 transition adjustment				0
Retained Earnings
Balance	547,512	591,533	647,356	637,757	591,533	637,757
Net earnings (loss)	52,086	(4,776)	34,002	54,942
Other comprehensive income (loss)	0	0	0	0
Common shares issued, net of withholding tax	0	0	0	0
Common shares in NQ plans	0	0	0	0
Stock-based compensation	0	0	0	0
Purchases and retirement of common shares		(25,785)	(56,041)	(32,849)
Cash dividends declared	(13,446)	(13,460)	(13,401)	(13,668)
Dividends to noncontrolling interest	0		0	0
Balance	586,152	547,512	611,916	647,356	586,152	611,916
Retained Earnings | Accounting Standards Update 2014-09
ASC 606 transition adjustment				1,174
Parent
Balance	787,973	831,246	919,519	918,769	831,246	918,769
Net earnings (loss)	52,086	(4,776)	34,002	54,942
Other comprehensive income (loss)	9,970	3,156	(11,245)	(5,745)
Common shares issued, net of withholding tax	(3,811)	(3,213)	(658)	(4,091)
Common shares in NQ plans	239	74	306	152
Stock-based compensation	2,880	4,545	3,730	4,838
Purchases and retirement of common shares		(29,599)	(63,581)	(36,852)
Cash dividends declared	(13,446)	(13,460)	(13,401)	(13,668)
Dividends to noncontrolling interest	0		0	0
Balance	835,891	787,973	868,672	919,519	835,891	868,672
Parent | Accounting Standards Update 2014-09
ASC 606 transition adjustment				1,174
Noncontrolling Interest
Balance	119,469	117,148	117,855	117,606	117,148	117,606
Net earnings (loss)	4,836	2,321	3,790	2,016
Other comprehensive income (loss)	0	0	(55)	(17)
Common shares issued, net of withholding tax	0	0	0	0
Common shares in NQ plans	0	0	0	0
Stock-based compensation	0	0	0	0
Purchases and retirement of common shares		0	0	0
Cash dividends declared	0	0	0	0
Dividends to noncontrolling interest	(1,453)		(4,007)	(2,320)
Balance	$ 122,852	$ 119,469	$ 117,583	117,855	$ 122,852	$ 117,583
Noncontrolling Interest | Accounting Standards Update 2014-09
ASC 606 transition adjustment				$ 570