Schedule Of Combined Financial Information for Unconsolidated Affiliates (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	May 31, 2012
Investments in and Advances to Affiliates [Line Items]
Current assets	$ 632,088	$ 626,975
Noncurrent assets	352,672	345,500
Total assets	984,760	972,475
Current liabilities	186,131	174,016
Current maturities of long-term debt	5,323	5,305
Long-term debt	275,970	289,308
Other noncurrent liabilities	20,832	21,934
Equity	496,504	481,912
Total liabilities and equity	$ 984,760	$ 972,475