DERIVATIVES - Pre-Tax Effects of Derivatives Not Designated as Hedging (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ (144,000,000)	$ 149,000,000	$ 233,000,000
Energy-related derivatives | Natural gas revenues
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	(117,000,000)	134,000,000	223,000,000
Energy-related derivatives | Cost of natural gas
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	(27,000,000)	15,000,000	10,000,000
Weather derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 0	$ 9,000,000	$ 3,000,000