FAIR VALUE OF FINANCIAL INSTRUMENTS (Debt) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Estimate Of Fair Value Fair Value Disclosure [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	$ 603,968	$ 626,110
Estimate Of Fair Value Fair Value Disclosure [Member] | Industrial Revenue Bond [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	8,843	9,004
Estimate Of Fair Value Fair Value Disclosure [Member] | Senior Notes Five Seventy Four [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	131,861	134,982
Estimate Of Fair Value Fair Value Disclosure [Member] | Senior Notes Five Fifty One [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	173,476	172,871
Estimate Of Fair Value Fair Value Disclosure [Member] | Senior Notes Three Eighty Four [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	99,452	101,886
Estimate Of Fair Value Fair Value Disclosure [Member] | Senior Notes Four Twenty Four [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	187,835	204,965
Estimate Of Fair Value Fair Value Disclosure [Member] | Other Debt Obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	2,501	2,402
Carrying Reported Amount Fair Value Disclosure [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	573,652	586,430
Carrying Reported Amount Fair Value Disclosure [Member] | Industrial Revenue Bond [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	8,843	9,004
Carrying Reported Amount Fair Value Disclosure [Member] | Senior Notes Five Seventy Four [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	125,021	125,024
Carrying Reported Amount Fair Value Disclosure [Member] | Senior Notes Five Fifty One [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	150,000	150,000
Carrying Reported Amount Fair Value Disclosure [Member] | Senior Notes Three Eighty Four [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	99,452	100,000
Carrying Reported Amount Fair Value Disclosure [Member] | Senior Notes Four Twenty Four [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	187,835	200,000
Carrying Reported Amount Fair Value Disclosure [Member] | Other Debt Obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	$ 2,501	$ 2,402