BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Carrying Amount
Summary of the fair value and carrying value of debt
Total debt	$ 1,705,638	$ 1,773,039
Carrying Amount | Fixed rate debt
Summary of the fair value and carrying value of debt
Total debt	809,138	794,039
Carrying Amount | Floating rate debt
Summary of the fair value and carrying value of debt
Total debt	896,500	979,000
Fair Value
Summary of the fair value and carrying value of debt
Total debt	1,747,000	1,781,000
Fair Value | Fixed rate debt
Summary of the fair value and carrying value of debt
Total debt	854,000	792,000
Fair Value | Floating rate debt
Summary of the fair value and carrying value of debt
Total debt	$ 893,000	$ 989,000