FAIR VALUE OF FINANCIAL INSTRUMENTS (Debt) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term Debt	$ 588,126	$ 586,430
Estimate Of Fair Value Fair Value Disclosure [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long Term Debt Fair Value	616,178	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	8,826	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	132,179	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	170,890	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	100,597	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	201,194	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	2,492	2,402
Carrying Reported Amount Fair Value Disclosure [Member] | Industrial Revenue Bond [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term Debt	8,826	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	125,017	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	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	100,597	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	201,194	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	$ 2,492	$ 2,402