FAIR VALUE MEASUREMENTS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 item	Mar. 31, 2012 item	Dec. 31, 2012
Financial Assets and Liabilities Fair Value Measurement
Number of non-financial assets and liabilities impaired	0	0
Assets
Deferred compensation plan	$ 11,372		$ 10,608
Derivative Instruments	4,215		50,824
Total Assets	15,587		61,432
Liabilities
Deferred Compensation Plan	29,429		23,893
Derivative instruments	29,899		192
Total Liabilities	59,328		24,085
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Deferred compensation plan	11,372		10,608
Total Assets	11,372		10,608
Liabilities
Deferred Compensation Plan	29,429		23,893
Total Liabilities	29,429		23,893
Significant Other Observable Inputs (Level 2)
Assets
Derivative Instruments	4,215		9,473
Total Assets	4,215		9,473
Significant Unobservable Inputs (Level 3)
Assets
Derivative Instruments			41,351
Total Assets			41,351
Liabilities
Derivative instruments	29,899		192
Total Liabilities	$ 29,899		$ 192