Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Apr. 30, 2012
Financial Assets (Liabilities):
Derivative instruments	$ 10,745
Notes 5.875 Percent [Member]
Financial Assets (Liabilities):
Interest rate (as a percent)	5.875%	5.875%		5.875%
Notes 5.875 Percent [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Assets (Liabilities):
Interest rate (as a percent)	5.875%
Notes 4.375 Percent [Member]
Financial Assets (Liabilities):
Interest rate (as a percent)	4.375%	4.375%	4.375%
Notes 4.375 Percent [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial Assets (Liabilities):
Interest rate (as a percent)	4.375%
Reported Value Measurement [Member]
Financial Assets (Liabilities):
Derivative instruments	$ 11,246
Reported Value Measurement [Member] \| Notes 5.875 Percent [Member]
Financial Assets (Liabilities):
Long-term debt	(743,022)	$ (741,657)
Reported Value Measurement [Member] \| Notes 4.375 Percent [Member]
Financial Assets (Liabilities):
Long-term debt	(742,598)	(741,519)
Estimate of Fair Value Measurement [Member]
Financial Assets (Liabilities):
Derivative instruments	11,246
Estimate of Fair Value Measurement [Member] \| Notes 5.875 Percent [Member]
Financial Assets (Liabilities):
Long-term debt	(723,750)	(776,250)
Estimate of Fair Value Measurement [Member] \| Notes 4.375 Percent [Member]
Financial Assets (Liabilities):
Long-term debt	$ (683,318)	$ (720,000)