REVENUE FROM CONTRACTS WITH CUSTOMERS Table 1 - Adoption Impact of ASC 606 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 490,363	$ 440,566	$ 1,452,448	$ 1,363,484
Operating income (loss)	95,277	91,717	273,595	262,260
Net income (loss)	$ 48,136	$ 38,592	$ 203,668	$ 122,782
Basic net loss per common unit	$ (3.49)	$ 0.15	$ (2.50)	$ 0.65
Calculated under Revenue Guidance in Effect before Topic 606 [Member] \| Revenue Recognition [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 490,799		$ 1,457,231
Operating income (loss)	95,713		278,378
Net income (loss)	$ 48,572		$ 208,451
Basic net loss per common unit	$ (3.49)		$ (2.45)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Revenue Recognition [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ (436)		$ (4,783)
Operating income (loss)	(436)		(4,783)
Net income (loss)	$ (436)		$ (4,783)
Basic net loss per common unit	$ 0.00		$ (0.05)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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