Risk-free interest rate assumption used in valuing an instrument.

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Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Jan. 09, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unsecured notes payable	$ 450,000	$ 450,000	$ 250,000
Fair value of interest rate swap	1,934	1,934	1,448
Interest Rate Swap
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unrealized gain (loss) on derivatives	(457)	486
Interest Rate Swap \| Deferred Credits and Other Liabilities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of interest rate swap	1,934	1,934
Amended and Restated Credit Facility
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unsecured notes payable				$ 100,000
Fair Value, Inputs, Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of interest rate swap	$ 1,934	$ 1,934	$ 1,448
Fair Value, Inputs, Level 2 \| Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value assumptions, interest rate		3.63%
Fair Value, Inputs, Level 2 \| Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value assumptions, interest rate		5.69%