Schedule of Combined Financial Information for Unconsolidated Affiliates (Detail) - Unconsolidated Affiliates - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015	May. 31, 2015
Investments in and Advances to Affiliates [Line Items]
Cash		$ 132,893		$ 132,893		$ 101,011
Receivable from member	[1]	6,902		6,902		11,092
Other current assets		434,533		434,533		491,507
Noncurrent assets		376,416		376,416		318,939
Total assets		950,744		950,744		922,549
Current liabilities		131,308		131,308		184,028
Short-term borrowings		16,684		16,684
Current maturities of long-term debt		3,721		3,721		4,489
Long-term debt		269,261		269,261		272,861
Other noncurrent liabilities		21,133		21,133		20,471
Equity		508,637		508,637		440,700
Total liabilities and equity		950,744		950,744		$ 922,549
Net sales		376,448	$ 356,604	1,170,096	$ 1,137,866
Gross margin		83,251	67,636	257,036	232,580
Operating income		54,801	41,335	171,857	154,678
Depreciation and amortization		7,905	8,827	24,070	26,932
Interest expense		2,038	2,157	6,333	6,492
Other income (expense)	[2]	(59)	(79)	23,505	(208)
Income tax expense		2,625	2,555	7,348	8,107
Net earnings		$ 51,994	$ 37,859	$ 186,063	$ 141,789

[1] Represents cash owed from a joint venture partner as a result of centralized cash management.

[2] The increase in other income for the nine months ended February 29, 2016, as compared to the comparable period in the prior year is primarily attributable to the impact of ClarkDietrich's legal settlement related to successful disparagement litigation brought against several competitors in an industry trade association.