Condensed Consolidating Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2013	May 31, 2013	Nov. 30, 2012	May 31, 2012
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	$ 82,362	$ 61,296	$ 71,782	$ 88,027
Receivables – net	122,382	126,922
Inventories	112,557	105,054
Deferred income taxes and prepaid expenses	21,929	27,294
TOTAL CURRENT ASSETS	339,230	320,566
Property, plant and equipment – net	1,203,654	1,226,396
Goodwill	40,575	40,575
Real estate and investments	31,582	29,471
Deferred other charges	18,050	18,817
Investment in subsidiaries	0	0
Long-term intercompany receivables	0	0
TOTAL ASSETS	1,633,091	1,635,825
Accounts payable	73,943	69,061
Accrued interest, compensation and other	72,197	62,336
Current portion of long-term debt	2,229	1,872
TOTAL CURRENT LIABILITIES	148,369	133,269
LONG-TERM DEBT	657,068	657,935
Long-term intercompany payables	0	0
DEFERRED INCOME TAXES AND OTHER CREDITS	85,967	91,157
Shareholders' equity	741,687	753,464
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,633,091	1,635,825
Parent Company
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	78,070	58,791	68,356	84,713
Receivables – net	0	0
Inventories	0	0
Deferred income taxes and prepaid expenses	187	615
TOTAL CURRENT ASSETS	78,257	59,406
Property, plant and equipment – net	0	0
Goodwill	0	0
Real estate and investments	2,176	1,080
Deferred other charges	210,443	210,838
Investment in subsidiaries	1,081,369	1,061,854
Long-term intercompany receivables	117,090	167,778
TOTAL ASSETS	1,489,335	1,500,956
Accounts payable	60	46
Accrued interest, compensation and other	26,681	26,416
Current portion of long-term debt	0	0
TOTAL CURRENT LIABILITIES	26,741	26,462
LONG-TERM DEBT	650,245	650,245
Long-term intercompany payables	18,729	18,743
DEFERRED INCOME TAXES AND OTHER CREDITS	51,933	52,042
Shareholders' equity	741,687	753,464
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,489,335	1,500,956
Guarantor Subsidiaries
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	4,292	2,505	3,426	3,314
Receivables – net	122,382	126,922
Inventories	112,557	105,054
Deferred income taxes and prepaid expenses	21,897	26,834
TOTAL CURRENT ASSETS	261,128	261,315
Property, plant and equipment – net	1,203,654	1,226,396
Goodwill	40,575	40,575
Real estate and investments	29,406	28,391
Deferred other charges	7,888	7,744
Investment in subsidiaries	0	0
Long-term intercompany receivables	18,737	18,743
TOTAL ASSETS	1,561,388	1,583,164
Accounts payable	73,883	69,015
Accrued interest, compensation and other	45,671	36,075
Current portion of long-term debt	2,229	1,872
TOTAL CURRENT LIABILITIES	121,783	106,962
LONG-TERM DEBT	6,823	7,690
Long-term intercompany payables	117,098	167,778
DEFERRED INCOME TAXES AND OTHER CREDITS	234,315	238,880
Shareholders' equity	1,081,369	1,061,854
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,561,388	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	(200,281)	(199,765)
Investment in subsidiaries	(1,081,369)	(1,061,854)
Long-term intercompany receivables	(135,827)	(186,521)
TOTAL ASSETS	(1,417,632)	(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	(135,827)	(186,521)
DEFERRED INCOME TAXES AND OTHER CREDITS	(200,281)	(199,765)
Shareholders' equity	(1,081,369)	(1,061,854)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ (1,417,632)	$ (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.