FAIR VALUE FAIR VALUE (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	$ 105,623	$ 161,361	$ 116,376	$ 130,324
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	105,623	161,361
Restricted cash	3,026	3,022
Long-term debt	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Long-term debt	430,742	467,319
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Long-term debt	0	0
Estimate of Fair Value Measurement | Fair Value, Measurements, Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	105,623	161,361
Restricted cash	3,026	3,022
Long-term debt	$ 590,057	$ 591,543