EQUITY METHOD INTERESTS - Summarized Financial Information of Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues		$ 0
Operating expenses		674
Operating income (loss)		(674)
Net income (loss)		(674)
Other comprehensive loss		0
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets		3
Noncurrent assets		1,130,998
Total assets		1,131,001
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Current liabilities		161,489
Noncurrent liabilities		1,269
Equity		968,243
Total liabilities and equity		1,131,001
Gulf Coast Express Pipeline LLC
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	$ 132,103	2,609
Operating expenses	24,047	432
Operating income (loss)	108,056	2,177
Net income (loss)	109,997	3,685
Other comprehensive loss	0	0
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets	72,412	74,304
Noncurrent assets	1,766,150	817,895
Total assets	1,838,562	892,199
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Current liabilities	48,128	246,288
Noncurrent liabilities	605	0
Equity	1,789,829	645,911
Total liabilities and equity	1,838,562	892,199
EPIC Crude Holdings, LP
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	40,756	0
Operating expenses	108,519	7,430
Operating income (loss)	(67,763)	(7,430)
Net income (loss)	(72,535)	(8,939)
Other comprehensive loss	(7,681)	0
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets	190,474	374,307
Noncurrent assets	2,017,669	332,662
Total assets	2,208,143	706,969
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Current liabilities	188,299	388,664
Noncurrent liabilities	956,744	0
Equity	1,063,100	318,305
Total liabilities and equity	2,208,143	706,969
Permian Highway Pipeline
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	0	0
Operating expenses	93	61
Operating income (loss)	(93)	(61)
Net income (loss)	1,587	(61)
Other comprehensive loss	0	0
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets	84,999	2,836
Noncurrent assets	1,252,571	95,368
Total assets	1,337,570	98,204
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Current liabilities	203,657	8,376
Noncurrent liabilities	0	0
Equity	1,133,913	89,828
Total liabilities and equity	1,337,570	$ 98,204
Breviloba LLC
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenues	129,559
Operating expenses	48,190
Operating income (loss)	81,369
Net income (loss)	81,469
Other comprehensive loss	0
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Current assets	93,169
Noncurrent assets	1,399,356
Total assets	1,492,525
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Current liabilities	37,599
Noncurrent liabilities	1,108
Equity	1,453,818
Total liabilities and equity	$ 1,492,525