Investments in Unconsolidated Affiliates - Schedule of Combined Financial Information for Unconsolidated Affiliates (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017	May 31, 2018
Equity Method Investments And Joint Ventures [Abstract]
Cash	$ 35,079		$ 35,079		$ 52,812
Other current assets	625,214		625,214		590,578
Current assets for discontinued operations	35,390		35,390		37,640
Noncurrent assets	364,305		364,305		358,927
Total assets	1,059,988		1,059,988		1,039,957
Current liabilities	256,608		256,608		166,493
Current liabilities for discontinued operations	8,884		8,884		7,142
Short-term borrowings	38,366		38,366		26,599
Current maturities of long-term debt	8,173		8,173		23,243
Long-term debt	323,598		323,598		259,588
Other noncurrent liabilities	17,452		17,452		17,536
Equity	406,907		406,907		539,356
Total liabilities and equity	1,059,988		1,059,988		$ 1,039,957
Net sales	480,716	$ 412,617	979,261	$ 855,241
Gross margin	75,515	71,122	179,327	157,357
Operating income	44,592	34,604	116,968	91,767
Depreciation and amortization	6,581	5,935	13,058	13,128
Interest expense	3,382	2,461	6,307	4,953
Income tax expense	3,568	1,816	8,093	3,164
Net earnings from continuing operations	36,523	31,893	101,417	82,937
Net earnings (loss) from discontinued operations	2,028	(1,703)	3,712	(273)
Net earnings	$ 38,551	$ 30,190	$ 105,129	$ 82,664