DEBT (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Total debt, including current portion	$ 1,585,190,000	$ 1,818,603,000
Less current portion of total debt	0	233,903,000
Total long-term debt	1,585,190,000	1,584,700,000
Aggregate maturities of debt [Abstract]
2013	0
2014	375,097,000
2015	228,845,000
2016	0
2017	383,235,000
Thereafter	600,000,000
Total	1,587,177,000
Senior notes 5.875% due 1/15/12 [Member]
Debt Instrument [Line Items]
Total debt, including current portion	0	233,903,000
Stated interest rate (in hundredths)	5.875%	5.875%
Maturity date	Jan. 15, 2012	Jan. 15, 2012
Repayment of senior notes	233,900,000
Senior notes 6.300% Due 8/15/14 [Member]
Debt Instrument [Line Items]
Total debt, including current portion	374,718,000	374,490,000
Stated interest rate (in hundredths)	6.30%	6.30%
Maturity date	Aug. 15, 2014	Aug. 15, 2014
Unamortized discount	379,000
Senior notes 6.125% due 1/15/15 [Member]
Debt Instrument [Line Items]
Total debt, including current portion	228,845,000	228,845,000
Stated interest rate (in hundredths)	6.125%	6.125%
Maturity date	Jan. 15, 2015	Jan. 15, 2015
Senior notes 5.950% due 3/15/17 [Member]
Debt Instrument [Line Items]
Total debt, including current portion	382,639,000	382,497,000
Stated interest rate (in hundredths)	5.95%	5.95%
Maturity date	Mar. 15, 2017	Mar. 15, 2017
Unamortized discount	596,000
Senior notes 5.450% Due 6/7/21 [Member]
Debt Instrument [Line Items]
Total debt, including current portion	598,988,000	598,868,000
Stated interest rate (in hundredths)	5.45%	5.45%
Maturity date	Jun. 07, 2021	Jun. 07, 2021
Unamortized discount	1,012,000
Aggregate principal amount of senior notes		600,000,000
Issue Price	99.80%
Revolving Credit Due 2012 [Member]
Debt Instrument [Line Items]
Repayment of revolving credit facility		380,000,000
Revolving Credit Due 2016 [Member]
Debt Instrument [Line Items]
Total debt, including current portion	0
Unsecured revolving credit agreement	750,000,000
Maximum borrowing capacity under revolving credit agreement	$ 1,000,000,000
Commitment fees under revolving credit agreement, minimum (in hundredths)	0.20%
Commitment fees under revolving credit agreement, maximum (in hundredths)	0.40%
Leverage ratio required under debt covenants	3 to 1
Basis spread for Eurodollar Rate advances, minimum (in hundredths)	1.05%
Basis spread for Eurodollar Rate advances, maximum (in hundredths)	1.85%
Term of Revolving Credit Facility	5