Condensed Consolidating Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2013	Aug. 31, 2012
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	$ 233,082	$ 174,523
Cost of products sold	202,416	159,323
GROSS PROFIT	30,666	15,200
Selling, general and administrative	18,553	17,557
Interest expense	17,371	7,777
Other income, net	(5,857)	(2,599)
Intercompany other income	0	0
Income (loss) from continuing operations before the following items	599	(7,535)
Income taxes (benefit)	170	(139)
Equity in earnings of subsidiaries	0	0
NET INCOME (LOSS) FROM CONTINUING OPERATIONS	429	(7,396)
Net income from discontinued operations	0	4,738
Net income (loss)	429	(2,658)
Comprehensive loss	438	(2,290)
Parent Company
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	0	0
Cost of products sold	0	0
GROSS PROFIT	0	0
Selling, general and administrative	2,464	2,354
Interest expense	17,272	16,988
Other income, net	(44)	(23)
Intercompany other income	(882)	(882)
Income (loss) from continuing operations before the following items	(18,810)	(18,437)
Income taxes (benefit)	(391)	67
Equity in earnings of subsidiaries	18,848	15,846
NET INCOME (LOSS) FROM CONTINUING OPERATIONS	429	(2,658)
Net income from discontinued operations	0	0
Net income (loss)	429	(2,658)
Comprehensive loss	429	(2,658)
Guarantor Subsidiaries
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	233,082	174,523
Cost of products sold	202,416	159,323
GROSS PROFIT	30,666	15,200
Selling, general and administrative	16,089	15,203
Interest expense	0	0
Other income, net	(5,813)	(2,576)
Intercompany other income	981	(8,329)
Income (loss) from continuing operations before the following items	19,409	10,902
Income taxes (benefit)	561	(206)
NET INCOME (LOSS) FROM CONTINUING OPERATIONS	18,848	11,108
Net income from discontinued operations	0	4,738
Net income (loss)	18,848	15,846
Comprehensive loss	18,857	16,214
Consolidation, Eliminations
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	0	0
Cost of products sold	0	0
GROSS PROFIT	0	0
Selling, general and administrative	0	0
Interest expense	99	(9,211)
Other income, net	0	0
Intercompany other income	(99)	9,211
Income (loss) from continuing operations before the following items	0	0
Income taxes (benefit)	0	0
Equity in earnings of subsidiaries	(18,848)	(15,846)
NET INCOME (LOSS) FROM CONTINUING OPERATIONS	(18,848)	(15,846)
Net income from discontinued operations	0	0
Net income (loss)	(18,848)	(15,846)
Comprehensive loss	$ (18,848)	$ (15,846)