DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Schedule of Derivative Assets and Liabilities Measured at Fair Value (Details) - Recurring - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative asset	$ 24	$ 9
Derivative liability	221	103
Commodity Derivative Instruments
Derivative [Line Items]
Derivative asset, fair value	28
Derivative asset, netting	(4)
Derivative asset	24
Derivative liability, fair value	11
Derivative liability, netting	(4)
Derivative liability	7
Commodity Derivative Instruments | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative asset, fair value	0
Derivative liability, fair value	0
Commodity Derivative Instruments | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative asset, fair value	28
Derivative liability, fair value	11
Commodity Derivative Instruments | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative asset, fair value	0
Derivative liability, fair value	0
Pipeline Capacity Embedded Derivatives
Derivative [Line Items]
Derivative asset, fair value		8
Derivative asset, netting		0
Derivative asset		8
Derivative liability, fair value	45
Derivative liability, netting	0
Derivative liability	45
Pipeline Capacity Embedded Derivatives | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative asset, fair value		0
Derivative liability, fair value	0
Pipeline Capacity Embedded Derivatives | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative asset, fair value		8
Derivative liability, fair value	45
Pipeline Capacity Embedded Derivatives | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative asset, fair value		0
Derivative liability, fair value	0
Foreign Currency Derivative Instruments
Derivative [Line Items]
Derivative asset, fair value		1
Derivative asset, netting		0
Derivative asset		1
Derivative liability, fair value	4
Derivative liability, netting	0
Derivative liability	4
Foreign Currency Derivative Instruments | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative asset, fair value		0
Derivative liability, fair value	0
Foreign Currency Derivative Instruments | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative asset, fair value		1
Derivative liability, fair value	4
Foreign Currency Derivative Instruments | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative asset, fair value		0
Derivative liability, fair value	0
Preferred Units Embedded Derivative
Derivative [Line Items]
Derivative liability, fair value	165	103
Derivative liability, netting	0	0
Derivative liability	165	103
Preferred Units Embedded Derivative | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative liability, fair value	0	0
Preferred Units Embedded Derivative | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative liability, fair value	0	0
Preferred Units Embedded Derivative | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative liability, fair value	$ 165	$ 103