Condensed Consolidating Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2012	May 31, 2011	May 31, 2010	May 31, 2009
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	$ 88,027	$ 116,432	$ 74,946	$ 19,796
Receivables-net	98,836	85,817
Inventories	129,514	140,646
Deferred income taxes and prepaid expenses	19,007	22,040
Total current assets	335,384	364,935
Property, plant and equipment-net	1,195,596	1,155,421
Goodwill	1,715	1,715
Real estate and investments	20,865	6,749
Deferred income taxes and other charges	23,368	22,191
TOTAL ASSETS	1,576,928	1,551,011	1,531,747
Accounts payable	64,825	56,787
Accrued interest, compensation and other	61,317	58,848
Current portion of long-term debt	1,214	73
Total current liabilities	127,356	115,708
Long-term debt	656,949	652,403
OTHER CREDITS	96,352	87,318
Shareholders' equity	696,271	695,582	761,248
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,576,928	1,551,011
Parent Company
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	84,713	113,898	72,492	17,226
Deferred income taxes and prepaid expenses	99	77
Total current assets	84,812	113,975
Real estate and investments	664	677
Deferred income taxes and other charges	123,734	110,305
Investment in subsidiaries	987,519	945,039
Long-term intercompany receivables	246,298	264,779
TOTAL ASSETS	1,443,027	1,434,775
Accounts payable	108	34
Accrued interest, compensation and other	25,829	22,146
Current portion of long-term debt	4
Total current liabilities	25,941	22,180
Long-term debt	650,245	650,268
Long-term intercompany payables	18,747	18,751
OTHER CREDITS	51,823	47,994
Shareholders' equity	696,271	695,582
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,443,027	1,434,775
Guarantor Subsidiaries
Supplemental Balance Sheet Information [Line Items]
Cash and cash equivalents	3,314	2,534	2,454	2,570
Receivables-net	98,836	85,817
Inventories	129,514	140,646
Deferred income taxes and prepaid expenses	18,908	21,963
Total current assets	250,572	250,960
Property, plant and equipment-net	1,195,596	1,155,421
Goodwill	1,715	1,715
Real estate and investments	20,201	6,072
Deferred income taxes and other charges	7,356	6,242
Long-term intercompany receivables	18,747	18,751
TOTAL ASSETS	1,494,187	1,439,161
Accounts payable	64,717	56,753
Accrued interest, compensation and other	35,488	36,702
Current portion of long-term debt	1,210	73
Total current liabilities	101,415	93,528
Long-term debt	6,704	2,135
Long-term intercompany payables	246,298	264,779
Deferred income taxes	107,722	94,356
OTHER CREDITS	44,529	39,324
Shareholders' equity	987,519	945,039
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	1,494,187	1,439,161
Consolidation, Eliminations
Supplemental Balance Sheet Information [Line Items]
Deferred income taxes and other charges	(107,722)	(94,356)
Investment in subsidiaries	(987,519)	(945,039)
Long-term intercompany receivables	(265,045)	(283,530)
TOTAL ASSETS	(1,360,286)	(1,322,925)
Long-term intercompany payables	(265,045)	(283,530)
Deferred income taxes	(107,722)	(94,356)
Shareholders' equity	(987,519)	(945,039)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ (1,360,286)	$ (1,322,925)

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.