DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Schedule of Derivative Assets and Liabilities Measured at Fair Value (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Derivative asset	$ 10	$ 9
Liabilities:
Derivative liability	247	103
Commodity Derivative Instruments
Assets:
Derivative asset, fair value	12
Derivative asset, netting	(2)
Derivative asset	10
Liabilities:
Derivative liability, fair value	15
Derivative liability, netting	(2)
Derivative liability	13
Commodity Derivative Instruments | Quoted Price in Active Markets (Level 1)
Assets:
Derivative asset, fair value	0
Liabilities:
Derivative liability, fair value	0
Commodity Derivative Instruments | Significant Other Inputs (Level 2)
Assets:
Derivative asset, fair value	12
Liabilities:
Derivative liability, fair value	15
Commodity Derivative Instruments | Significant Unobservable Inputs (Level 3)
Assets:
Derivative asset, fair value	0
Liabilities:
Derivative liability, fair value	0
Pipeline Capacity Embedded Derivatives
Assets:
Derivative asset, fair value		8
Derivative asset, netting		0
Derivative asset		8
Liabilities:
Derivative liability, fair value	54
Derivative liability, netting	0
Derivative liability	54
Pipeline Capacity Embedded Derivatives | Quoted Price in Active Markets (Level 1)
Assets:
Derivative asset, fair value		0
Liabilities:
Derivative liability, fair value	0
Pipeline Capacity Embedded Derivatives | Significant Other Inputs (Level 2)
Assets:
Derivative asset, fair value		8
Liabilities:
Derivative liability, fair value	54
Pipeline Capacity Embedded Derivatives | Significant Unobservable Inputs (Level 3)
Assets:
Derivative asset, fair value		0
Liabilities:
Derivative liability, fair value	0
Foreign Currency Derivative Instruments
Assets:
Derivative asset, fair value		1
Derivative asset, netting		0
Derivative asset		1
Liabilities:
Derivative liability, fair value	1
Derivative liability, netting	0
Derivative liability	1
Foreign Currency Derivative Instruments | Quoted Price in Active Markets (Level 1)
Assets:
Derivative asset, fair value		0
Liabilities:
Derivative liability, fair value	0
Foreign Currency Derivative Instruments | Significant Other Inputs (Level 2)
Assets:
Derivative asset, fair value		1
Liabilities:
Derivative liability, fair value	1
Foreign Currency Derivative Instruments | Significant Unobservable Inputs (Level 3)
Assets:
Derivative asset, fair value		0
Liabilities:
Derivative liability, fair value	0
Preferred Units Embedded Derivative
Liabilities:
Derivative liability, fair value	179	103
Derivative liability, netting	0	0
Derivative liability	179	103
Preferred Units Embedded Derivative | Quoted Price in Active Markets (Level 1)
Liabilities:
Derivative liability, fair value	0	0
Preferred Units Embedded Derivative | Significant Other Inputs (Level 2)
Liabilities:
Derivative liability, fair value	0	0
Preferred Units Embedded Derivative | Significant Unobservable Inputs (Level 3)
Liabilities:
Derivative liability, fair value	$ 179	$ 103