Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

GOODWILL (Details) - USD ($) $ in Millions	12 Months Ended
GOODWILL (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
REGULATORY
Goodwill impairment charge	$ 0	$ 0	$ 59
Goodwill	$ 71	71
Long-term take-or-pay revenue	90.00%
North Baja
REGULATORY
Goodwill	$ 48	48
Tuscarora
REGULATORY
Goodwill	$ 23	$ 23
Tuscarora
REGULATORY
Goodwill impairment charge			59
Goodwill			$ 82