DEBT (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
DebtInstrumentLineItems
Current portion of long-term debt and short-term debt	$ 1,069us-gaap_DebtCurrent	$ 1,334us-gaap_DebtCurrent
Long-term debt	953,279us-gaap_LongTermDebtNoncurrent	958,604us-gaap_LongTermDebtNoncurrent
Carrying Reported Amount Fair Value Disclosure [Member]
DebtInstrumentLineItems
Long-term Debt	954,348	959,938
Current portion of long-term debt and short-term debt	1,069	1,334
Long-term debt	953,279	958,604
Carrying Reported Amount Fair Value Disclosure [Member] \| Industrial Revenue Bond [Member]
DebtInstrumentLineItems
Long-term Debt	8,400	8,400
Carrying Reported Amount Fair Value Disclosure [Member] \| Revolving Credit Facility [Member]
DebtInstrumentLineItems
Long-term Debt	0	50,000
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Five Fifty One [Member]
DebtInstrumentLineItems
Long-term Debt	150,000	150,000
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Three Eighty Four [Member]
DebtInstrumentLineItems
Long-term Debt	99,934	98,632
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Three Seventy [Member]
DebtInstrumentLineItems
Long-term Debt	225,000	225,000
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Three Eighty Five [Member]
DebtInstrumentLineItems
Long-term Debt	98,360	88,555
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Four Twenty Four [Member]
DebtInstrumentLineItems
Long-term Debt	197,237	173,557
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Four Zero Five [Member]
DebtInstrumentLineItems
Long-term Debt	74,348	64,411
Carrying Reported Amount Fair Value Disclosure [Member] \| Senior Notes Four Eleven [Member]
DebtInstrumentLineItems
Long-term Debt	100,000	100,000
Carrying Reported Amount Fair Value Disclosure [Member] \| Other Debt Obligations [Member]
DebtInstrumentLineItems
Long-term Debt		1,383
Estimate Of Fair Value Fair Value Disclosure [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	968,514	946,389
Current portion of long-term debt and short-term debt	1,069	1,334
Long-term debt	967,445	945,055
Estimate Of Fair Value Fair Value Disclosure [Member] \| Industrial Revenue Bond [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	8,400	8,400
Estimate Of Fair Value Fair Value Disclosure [Member] \| Revolving Credit Facility [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	0	50,000
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Five Fifty One [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	162,617	163,059
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Three Eighty Four [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	99,934	98,632
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Three Seventy [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	225,748	209,140
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Three Eighty Five [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	98,360	88,555
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Four Twenty Four [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	197,237	173,557
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Four Zero Five [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	74,348	64,411
Estimate Of Fair Value Fair Value Disclosure [Member] \| Senior Notes Four Eleven [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	100,801	89,252
Estimate Of Fair Value Fair Value Disclosure [Member] \| Other Debt Obligations [Member]
DebtInstrumentLineItems
Long Term Debt Fair Value	$ 1,069	$ 1,383

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19,20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

Name:	us-gaap_LongTermDebtNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
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Period Type:

- Details

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