DERIVATIVE CONTRACTS AND COLLATERALIZED INDEBTEDNESS - Location of Assets and Liabilities Within the Consolidated Balance Sheets (Details) - Not Designated as Hedging Instruments - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 2,634	$ 111,319
Liability Derivatives	378,287	132,978
Interest Rate Swap | Current derivative contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	0	1,975
Interest Rate Swap | Long-term derivative contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	2,634	0
Interest Rate Swap | Short-term liabilities under derivative contracts
Derivatives, Fair Value [Line Items]
Liability Derivatives	674	70
Interest Rate Swap | Long-term liabilities under derivative contracts
Derivatives, Fair Value [Line Items]
Liability Derivatives	(182,970)	(132,908)
Prepaid forward contracts | Long-term derivative contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	0	109,344
Prepaid forward contracts | Long-term liabilities under derivative contracts
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ (194,643)	$ 0