Condensed Consolidating Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2013	Nov. 30, 2012
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	$ 208,892	$ 167,693	$ 441,974	$ 342,216
Cost of products sold	194,735	155,939	397,151	315,262
GROSS PROFIT	14,157	11,754	44,823	26,954
Selling, general and administrative	19,655	17,067	38,207	34,623
Interest expense	17,423	7,457	34,794	15,235
Other income, net	(5,406)	(1,924)	(11,263)	(4,525)
Intercompany other income	0	0	0	0
Income (loss) from continuing operations before the following items	(17,515)	(10,846)	(16,915)	(18,379)
Income taxes (benefit)	125	(657)	295	(796)
Equity in earnings of subsidiaries	0	0	0	0
Net income (loss) from continuing operations	(17,640)	(10,189)	(17,210)	(17,583)
Net income (loss) from discontinued operations	0	(933)	0	3,805
Net income (loss)	(17,640)	(11,122)	(17,210)	(13,778)
Comprehensive loss	(17,631)	(11,025)	(17,190)	(13,313)
Parent Company
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	0	0	0	0
Cost of products sold	0	0	0	0
GROSS PROFIT	0	0	0	0
Selling, general and administrative	1,993	2,330	4,459	4,684
Interest expense	17,301	17,248	34,573	34,236
Other income, net	(14)	(26)	(58)	(49)
Intercompany other income	(873)	(874)	(1,755)	(1,755)
Income (loss) from continuing operations before the following items	(18,407)	(18,678)	(37,219)	(37,116)
Income taxes (benefit)	(125)	(143)	(515)	(76)
Equity in earnings of subsidiaries	642	7,413	19,494	23,262
Net income (loss) from continuing operations	(17,640)	(11,122)	(17,210)	(13,778)
Net income (loss) from discontinued operations	0	0	0	0
Net income (loss)	(17,640)	(11,122)	(17,210)	(13,778)
Comprehensive loss	(17,640)	(11,122)	(17,210)	(13,778)
Guarantor Subsidiaries
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	208,892	167,693	441,974	342,216
Cost of products sold	194,735	155,939	397,151	315,262
GROSS PROFIT	14,157	11,754	44,823	26,954
Selling, general and administrative	17,662	14,737	33,748	29,939
Interest expense	0	0	0	0
Other income, net	(5,392)	(1,898)	(11,205)	(4,476)
Intercompany other income	995	(8,917)	1,976	(17,246)
Income (loss) from continuing operations before the following items	892	7,832	20,304	18,737
Income taxes (benefit)	250	(514)	810	(720)
Net income (loss) from continuing operations	642	8,346	19,494	19,457
Net income (loss) from discontinued operations	0	(933)	0	3,805
Net income (loss)	642	7,413	19,494	23,262
Comprehensive loss	651	7,510	19,514	23,727
Consolidation, Eliminations
Schedule of Condensed Consolidating Statement of Operations [Line Items]
NET SALES	0	0	0	0
Cost of products sold	0	0	0	0
GROSS PROFIT	0	0	0	0
Selling, general and administrative	0	0	0	0
Interest expense	122	(9,791)	221	(19,001)
Other income, net	0	0	0	0
Intercompany other income	(122)	9,791	(221)	19,001
Income (loss) from continuing operations before the following items	0	0	0	0
Income taxes (benefit)	0	0	0	0
Equity in earnings of subsidiaries	(642)	(7,413)	(19,494)	(23,262)
Net income (loss) from continuing operations	(642)	(7,413)	(19,494)	(23,262)
Net income (loss) from discontinued operations	0	0	0	0
Net income (loss)	(642)	(7,413)	(19,494)	(23,262)
Comprehensive loss	$ (642)	$ (7,413)	$ (19,494)	$ (23,262)