Condensed Consolidating Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2013	May 31, 2013	Aug. 31, 2012	May 31, 2012
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	$ 48,472	$ 61,296	$ 60,871	$ 88,027
Receivables – net	142,032	126,922
Inventories	107,678	105,054
Deferred income taxes and prepaid expenses	26,564	27,294
Discontinued operations held for sale		0
TOTAL CURRENT ASSETS	324,746	320,566
Property, plant and equipment – net	1,211,056	1,226,396
Goodwill	40,575	40,575
Real estate and investments	30,062	29,471
Deferred other charges	19,359	18,817
Investment in subsidiaries	0	0
Long-term intercompany receivables	0	0
TOTAL ASSETS	1,625,798	1,635,825
Accounts payable	69,617	69,061
Accrued interest, compensation and other	49,541	62,336
Current portion of long-term debt	1,911	1,872
TOTAL CURRENT LIABILITIES	121,069	133,269
LONG-TERM DEBT	657,449	657,935
Long-term intercompany payables	0	0
DEFERRED INCOME TAXES AND OTHER CREDITS	89,954	91,157
Shareholders' equity	757,326	753,464
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,625,798	1,635,825
Parent Company
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	45,032	58,791	52,994	84,713
Receivables – net	0	0
Inventories	0	0
Deferred income taxes and prepaid expenses	361	615
TOTAL CURRENT ASSETS	45,393	59,406
Property, plant and equipment – net	0	0
Goodwill	0	0
Real estate and investments	415	1,080
Deferred other charges	210,408	210,838
Investment in subsidiaries	1,080,712	1,061,854
Long-term intercompany receivables	152,616	167,778
TOTAL ASSETS	1,489,544	1,500,956
Accounts payable	(141)	46
Accrued interest, compensation and other	11,347	26,416
Current portion of long-term debt	0	0
TOTAL CURRENT LIABILITIES	11,206	26,462
LONG-TERM DEBT	650,245	650,245
Long-term intercompany payables	18,742	18,743
DEFERRED INCOME TAXES AND OTHER CREDITS	52,025	52,042
Shareholders' equity	757,326	753,464
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,489,544	1,500,956
Guarantor Subsidiaries
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	3,440	2,505	7,877	3,314
Receivables – net	142,032	126,922
Inventories	107,678	105,054
Deferred income taxes and prepaid expenses	26,358	26,834
Discontinued operations held for sale		0
TOTAL CURRENT ASSETS	279,508	261,315
Property, plant and equipment – net	1,211,056	1,226,396
Goodwill	40,575	40,575
Real estate and investments	29,647	28,391
Deferred other charges	8,716	7,744
Investment in subsidiaries	0	0
Long-term intercompany receivables	18,742	18,743
TOTAL ASSETS	1,588,244	1,583,164
Accounts payable	69,758	69,015
Accrued interest, compensation and other	38,349	36,075
Current portion of long-term debt	1,911	1,872
TOTAL CURRENT LIABILITIES	110,018	106,962
LONG-TERM DEBT	7,204	7,690
Long-term intercompany payables	152,616	167,778
DEFERRED INCOME TAXES AND OTHER CREDITS	237,694	238,880
Shareholders' equity	1,080,712	1,061,854
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,588,244	1,583,164
Consolidation, Eliminations
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	0	0	0	0
Receivables – net	0	0
Inventories	0	0
Deferred income taxes and prepaid expenses	(155)	(155)
TOTAL CURRENT ASSETS	(155)	(155)
Property, plant and equipment – net	0	0
Goodwill	0	0
Real estate and investments	0	0
Deferred other charges	(199,765)	(199,765)
Investment in subsidiaries	(1,080,712)	(1,061,854)
Long-term intercompany receivables	(171,358)	(186,521)
TOTAL ASSETS	(1,451,990)	(1,448,295)
Accounts payable	0	0
Accrued interest, compensation and other	(155)	(155)
Current portion of long-term debt	0	0
TOTAL CURRENT LIABILITIES	(155)	(155)
LONG-TERM DEBT	0	0
Long-term intercompany payables	(171,358)	(186,521)
DEFERRED INCOME TAXES AND OTHER CREDITS	(199,765)	(199,765)
Shareholders' equity	(1,080,712)	(1,061,854)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ (1,451,990)	$ (1,448,295)

Represents deferred tax assets net, current and prepaid expense, current. Deferred Tax Assets, Net, Current represents the current portion of the aggregate tax effects as of the balance sheet date of all future tax deductions arising from temporary differences between tax basis and generally accepted accounting principles basis recognition of assets, liabilities, revenues and expenses, which can only be deducted for tax purposes when permitted under enacted tax laws; after deducting the allocated valuation allowance, if any, to reduce such amount to net realizable value. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. An unrecognized tax benefit that is directly related to a position taken in a tax year that results in a net operating loss carryforward should be presented as a reduction of the related deferred tax asset. Prepaid expense, current represents the sum of the amounts paid in advance for capitalized costs that will be expensed with the passage of time or the occurrence of a triggering event, and will be charged against earnings within one year or the normal operating cycle, if longer.

No definition available.