EQUITY INVESTMENTS - Financial Information of Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Method Investments and Joint Ventures [Abstract]
Representation of investee financial information in the summarized equity method investments (as a percent)	100.00%
BALANCE SHEET DATA:
Current assets	$ 26,910	$ 62,437
Noncurrent assets	126,456	109,347
Total assets	153,366	171,784
Current liabilities	11,474	28,242
Other liabilities	43,344	50,598
Combined equity	98,548	92,944
Total liabilities and combined equity	153,366	171,784
INCOME STATEMENT DATA:
Revenue	92,501	88,417	$ 79,266
Costs and expenses	(56,906)	(48,563)	(58,697)
Non-operating expense	(15,903)	(13,826)	(6,808)
Net income	$ 19,692	$ 26,028	$ 13,761