Changes in Equity - Summary of Changes in Equity by Component and in Total (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	Feb. 28, 2019	Feb. 28, 2018
Beginning Balance	$ 986,255	$ 1,037,374	$ 1,036,375	$ 1,042,783	$ 1,082,727	$ 1,073,929	$ 1,036,375	$ 1,073,929
Net earnings	29,548	37,792	56,958	78,297	41,622	48,074	124,298	167,993
Other comprehensive income (loss)	917	(11,300)	(5,762)	9,237	(699)	17,753	(16,145)	26,291
Common shares issued, net of withholding tax	104	(658)	(4,091)	581	(722)	(3,274)
Common shares in NQ plans	80	306	152	117	350	536
Stock-based compensation	1,947	3,730	4,838	3,212	3,169	4,822
Purchases and retirement of common shares	(28,587)	(63,581)	(36,852)	(47,418)	(67,448)	(45,076)
Cash dividends declared	(13,256)	(13,401)	(13,668)	(12,822)	(13,020)	(13,317)
Dividends to noncontrolling interest		(4,007)	(2,320)		(3,196)	(720)
Ending Balance	977,008	986,255	1,037,374	1,073,987	1,042,783	1,082,727	977,008	1,073,987
Accounting Standards Update 2014-09
ASC 606 transition adjustment			1,744
Additional Paid-in Capital
Beginning Balance	288,326	292,488	295,592	296,792	301,240	303,391	295,592	303,391
Common shares issued, net of withholding tax	104	(658)	(4,091)	581	(722)	(3,274)
Common shares in NQ plans	80	306	152	117	350	536
Stock-based compensation	1,947	3,730	4,838	3,212	3,169	4,822
Purchases and retirement of common shares	(4,061)	(7,540)	(4,003)	(4,831)	(7,245)	(4,235)
Ending Balance	286,396	288,326	292,488	295,871	296,792	301,240	286,396	295,871
AOCI Attributable to Parent
Beginning Balance	(31,570)	(20,325)	(14,580)	(11,080)	(10,461)	(27,775)	(14,580)	(27,775)
Other comprehensive income (loss)	889	(11,245)	(5,745)	9,126	(619)	17,314
Ending Balance	(30,681)	(31,570)	(20,325)	(1,954)	(11,080)	(10,461)	(30,681)	(1,954)
Retained Earnings
Beginning Balance	611,916	647,356	637,757	633,575	667,395	676,019	637,757	676,019
Net earnings	26,773	34,002	54,942	79,088	39,403	45,534
Purchases and retirement of common shares	(24,526)	(56,041)	(32,849)	(42,587)	(60,203)	(40,841)
Cash dividends declared	(13,256)	(13,401)	(13,668)	(12,822)	(13,020)	(13,317)
Ending Balance	600,907	611,916	647,356	657,254	633,575	667,395	600,907	657,254
Retained Earnings | Accounting Standards Update 2014-09
ASC 606 transition adjustment			1,174
Parent
Beginning Balance	868,672	919,519	918,769	919,287	958,174	951,635	918,769	951,635
Net earnings	26,773	34,002	54,942	79,088	39,403	45,534
Other comprehensive income (loss)	889	(11,245)	(5,745)	9,126	(619)	17,314
Common shares issued, net of withholding tax	104	(658)	(4,091)	581	(722)	(3,274)
Common shares in NQ plans	80	306	152	117	350	536
Stock-based compensation	1,947	3,730	4,838	3,212	3,169	4,822
Purchases and retirement of common shares	(28,587)	(63,581)	(36,852)	(47,418)	(67,448)	(45,076)
Cash dividends declared	(13,256)	(13,401)	(13,668)	(12,822)	(13,020)	(13,317)
Ending Balance	856,622	868,672	919,519	951,171	919,287	958,174	856,622	951,171
Parent | Accounting Standards Update 2014-09
ASC 606 transition adjustment			1,174
Noncontrolling Interest
Beginning Balance	117,583	117,855	117,606	123,496	124,553	122,294	117,606	122,294
Net earnings	2,775	3,790	2,016	(791)	2,219	2,540
Other comprehensive income (loss)	28	(55)	(17)	111	(80)	439
Dividends to noncontrolling interest		(4,007)	(2,320)		(3,196)	(720)
Ending Balance	$ 120,386	$ 117,583	117,855	$ 122,816	$ 123,496	$ 124,553	$ 120,386	$ 122,816
Noncontrolling Interest | Accounting Standards Update 2014-09
ASC 606 transition adjustment			$ 570