FAIR VALUE MEASUREMENTS (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair value disclosures
Current Maturities	$ (75,000)	$ (75,000)
Long-Term Debt, excluding Current Maturities	1,067,000	1,012,000
Carrying Amount
Fair value disclosures
Long-Term Debt	1,142,000	1,087,000
Current Maturities	(75,000)	(75,000)
Long-Term Debt, excluding Current Maturities	1,067,000	1,012,000
Estimated Fair Value
Fair value disclosures
Long-Term Debt	1,235,176	1,213,474
Current Maturities	(75,301)	(77,175)
Long-Term Debt, excluding Current Maturities	$ 1,159,875	$ 1,136,299