Schedule of Combined Financial Information for Unconsolidated Affiliates (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Nov. 30, 2014		Nov. 30, 2013	Nov. 30, 2014		Nov. 30, 2013	May 31, 2014
Investments in and Advances to Affiliates [Line Items]
Cash	$ 53,333			$ 53,333			$ 52,997
Receivable from member	8,635	[1]		8,635	[1]		12,717	[1]
Other current assets	470,266			470,266			454,417
Noncurrent assets	290,261			290,261			294,001
Total assets	822,495			822,495			814,132
Current liabilities	156,959			156,959			128,595
Short-term borrowings	16,178			16,178			40,992
Current maturities of long-term debt	4,460			4,460			4,510
Long-term debt	266,107			266,107			268,350
Other noncurrent liabilities	18,664			18,664			20,217
Equity	360,127			360,127			351,468
Total liabilities and equity	822,495			822,495			814,132
Net sales	388,712		357,236	781,262		780,717
Gross margin	76,193		76,068	164,945		165,882
Operating income	49,864		51,532	113,343		116,072
Depreciation and amortization	8,983		9,104	18,105		19,441
Interest expense	2,173		2,233	4,335		4,456
Income tax expense	2,799		2,862	5,552		5,892
Net earnings	$ 44,490		$ 46,149	$ 103,930		$ 105,783

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