FAIR VALUE MEASUREMENTS - Recurring Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Liabilities
Restricted cash	$ 29	$ 46
Recurring
Assets
Fair value, assets	520	525
Liabilities
Fair value, liabilities	(3)	(2)
Net assets	517	523
Recurring \| FTRs \| Derivative Liabilities
Liabilities
Fair value, liabilities	(3)	(2)
Recurring \| FTRs \| Derivative Assets
Assets
Fair value, assets	0	11
Recurring \| Equity securities
Assets
Fair value, assets	2	2
Recurring \| U.S. state debt securities
Assets
Fair value, assets	271	266
Recurring \| Cash, cash equivalents and restricted cash
Assets
Fair value, assets	206	206
Recurring \| Other
Assets
Fair value, assets	41	40
Recurring \| Level 1
Assets
Fair value, assets	208	208
Liabilities
Fair value, liabilities	0	0
Net assets	208	208
Recurring \| Level 1 \| FTRs \| Derivative Liabilities
Liabilities
Fair value, liabilities	0	0
Recurring \| Level 1 \| FTRs \| Derivative Assets
Assets
Fair value, assets	0	0
Recurring \| Level 1 \| Equity securities
Assets
Fair value, assets	2	2
Recurring \| Level 1 \| U.S. state debt securities
Assets
Fair value, assets	0	0
Recurring \| Level 1 \| Cash, cash equivalents and restricted cash
Assets
Fair value, assets	206	206
Recurring \| Level 1 \| Other
Assets
Fair value, assets	0	0
Recurring \| Level 2
Assets
Fair value, assets	312	306
Liabilities
Fair value, liabilities	0	0
Net assets	312	306
Recurring \| Level 2 \| FTRs \| Derivative Liabilities
Liabilities
Fair value, liabilities	0	0
Recurring \| Level 2 \| FTRs \| Derivative Assets
Assets
Fair value, assets	0	0
Recurring \| Level 2 \| Equity securities
Assets
Fair value, assets	0	0
Recurring \| Level 2 \| U.S. state debt securities
Assets
Fair value, assets	271	266
Recurring \| Level 2 \| Cash, cash equivalents and restricted cash
Assets
Fair value, assets	0	0
Recurring \| Level 2 \| Other
Assets
Fair value, assets	41	40
Recurring \| Level 3
Assets
Fair value, assets	0	11
Liabilities
Fair value, liabilities	(3)	(2)
Net assets	(3)	9
Recurring \| Level 3 \| FTRs \| Derivative Liabilities
Liabilities
Fair value, liabilities	(3)	(2)
Recurring \| Level 3 \| FTRs \| Derivative Assets
Assets
Fair value, assets	0	11
Recurring \| Level 3 \| Equity securities
Assets
Fair value, assets	0	0
Recurring \| Level 3 \| U.S. state debt securities
Assets
Fair value, assets	0	0
Recurring \| Level 3 \| Cash, cash equivalents and restricted cash
Assets
Fair value, assets	0	0
Recurring \| Level 3 \| Other
Assets
Fair value, assets	$ 0	$ 0

Fair value of assets and liabilities net.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Fair value of financial and nonfinancial obligations.

+ References

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- Definition

Amount of cash restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=126999549&loc=SL98516268-108586

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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