FAIR VALUE MEASUREMENTS (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Assets:
Short-term investments	$ 245	$ 289
Price risk management instruments, netting	44	143
Price risk management instruments, assets	285	370
TOTAL ASSETS	5,219	5,558
Liabilities:
Price risk management instruments, netting	(25)	(27)
TOTAL LIABILITIES	249	242
Amount primarily related to deferred taxes on appreciation of investment value	731	783
Nuclear decommissioning trusts
Assets:
Short-term investments	73	22
Global equity securities	2,297	2,504
Fixed-income securities	1,966	2,024
TOTAL ASSETS	4,366	4,581
Rabbi trusts
Assets:
Fixed-income securities	99	104
Life insurance contracts	73	76
TOTAL ASSETS	172	180
Long-term disability trust
Assets:
Short-term investments	6	6
TOTAL ASSETS	151	138
Price Risk Derivative, Electricity
Assets:
Price risk management instruments, netting	4	6
Price risk management instruments, assets	240	229
Liabilities:
Price risk management instruments, netting	(16)	(24)
Price risk management instruments, liabilities	247	235
Price Risk Derivative, Gas
Assets:
Price risk management instruments, netting	40	137
Price risk management instruments, assets	45	141
Liabilities:
Price risk management instruments, netting	(9)	(3)
Price risk management instruments, liabilities	2	7
Level 1
Assets:
Short-term investments	245	289
Price risk management instruments, gross subject to netting	0	0
TOTAL ASSETS	3,756	3,979
Liabilities:
TOTAL LIABILITIES	0	0
Level 1 | Nuclear decommissioning trusts
Assets:
Short-term investments	73	22
Global equity securities	2,297	2,504
Fixed-income securities	1,135	1,158
TOTAL ASSETS	3,505	3,684
Level 1 | Rabbi trusts
Assets:
Fixed-income securities	0	0
Life insurance contracts	0	0
TOTAL ASSETS	0	0
Level 1 | Long-term disability trust
Assets:
Short-term investments	6	6
TOTAL ASSETS	6	6
Level 1 | Price Risk Derivative, Electricity
Assets:
Price risk management instruments, gross subject to netting	0	0
Liabilities:
Price risk management instruments, gross subject to netting	0	0
Level 1 | Price Risk Derivative, Gas
Assets:
Price risk management instruments, gross subject to netting	0	0
Liabilities:
Price risk management instruments, gross subject to netting	0	0
Level 2
Assets:
Short-term investments	0	0
Price risk management instruments, gross subject to netting	32	13
TOTAL ASSETS	1,035	1,059
Liabilities:
TOTAL LIABILITIES	41	21
Level 2 | Nuclear decommissioning trusts
Assets:
Short-term investments	0	0
Global equity securities	0	0
Fixed-income securities	831	866
TOTAL ASSETS	831	866
Level 2 | Rabbi trusts
Assets:
Fixed-income securities	99	104
Life insurance contracts	73	76
TOTAL ASSETS	172	180
Level 2 | Long-term disability trust
Assets:
Short-term investments	0	0
TOTAL ASSETS	0	0
Level 2 | Price Risk Derivative, Electricity
Assets:
Price risk management instruments, gross subject to netting	27	9
Liabilities:
Price risk management instruments, gross subject to netting	30	11
Level 2 | Price Risk Derivative, Gas
Assets:
Price risk management instruments, gross subject to netting	5	4
Liabilities:
Price risk management instruments, gross subject to netting	11	10
Level 3
Assets:
Short-term investments	0	0
Price risk management instruments, gross subject to netting	209	214
TOTAL ASSETS	209	214
Liabilities:
TOTAL LIABILITIES	233	248
Level 3 | Nuclear decommissioning trusts
Assets:
Short-term investments	0	0
Global equity securities	0	0
Fixed-income securities	0	0
TOTAL ASSETS	0	0
Level 3 | Rabbi trusts
Assets:
Fixed-income securities	0	0
Life insurance contracts	0	0
TOTAL ASSETS	0	0
Level 3 | Long-term disability trust
Assets:
Short-term investments	0	0
TOTAL ASSETS	0	0
Level 3 | Price Risk Derivative, Electricity
Assets:
Price risk management instruments, gross subject to netting	209	214
Liabilities:
Price risk management instruments, gross subject to netting	233	248
Level 3 | Price Risk Derivative, Gas
Assets:
Price risk management instruments, gross subject to netting	0	0
Liabilities:
Price risk management instruments, gross subject to netting	0	0
Fair Value Measured at Net Asset Value Per Share | Nuclear decommissioning trusts
Assets:
Assets measured at NAV	30	31
Fair Value Measured at Net Asset Value Per Share | Long-term disability trust
Assets:
Assets measured at NAV	$ 145	$ 132