Fair Value Measurements (Fair Value by Level) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets at fair value
Nuclear decommissioning trusts	$ 4,562	$ 4,120
SCE
Assets at fair value
Nuclear decommissioning trusts	$ 4,562	$ 4,120
Liabilities at fair value
Percentage of equity investments located in the United States (as a percent)	72.00%	71.00%
Collateralized mortgage obligations and other asset backed securities	$ 46	$ 67
Payables, net, related to investments	(111)	(143)
SCE \| Fair Value, Measurements, Recurring
Assets at fair value
Netting and Collateral	(15)	0
Derivative contracts, net	87	173
Other	18	30
Nuclear decommissioning trusts	4,673	4,263
Total assets	4,778	4,466
Liabilities at fair value
Netting and Collateral	(15)	(7)
Derivative contracts, net	1	6
Total liabilities	1	6
Net assets	4,777	4,460
Cash collateral posted	0	7
SCE \| Fair Value, Measurements, Recurring \| Level 1
Assets at fair value
Derivative contracts	0	0
Other	4	9
Nuclear decommissioning trusts	2,601	2,503
Total assets	2,605	2,512
Liabilities at fair value
Derivative contracts	0	0
Total liabilities	0	0
Net assets	2,605	2,512
SCE \| Fair Value, Measurements, Recurring \| Level 2
Assets at fair value
Derivative contracts	19	32
Other	14	21
Nuclear decommissioning trusts	2,072	1,760
Total assets	2,105	1,813
Liabilities at fair value
Derivative contracts	11	13
Total liabilities	11	13
Net assets	2,094	1,800
SCE \| Fair Value, Measurements, Recurring \| Level 3
Assets at fair value
Derivative contracts	83	141
Other	0	0
Nuclear decommissioning trusts	0	0
Total assets	83	141
Liabilities at fair value
Derivative contracts	5	0
Total liabilities	5	0
Net assets	78	141
SCE \| Fair Value, Measurements, Recurring \| Stocks
Assets at fair value
Nuclear decommissioning trusts	1,765	1,382
SCE \| Fair Value, Measurements, Recurring \| Stocks \| Level 1
Assets at fair value
Nuclear decommissioning trusts	1,765	1,382
SCE \| Fair Value, Measurements, Recurring \| Stocks \| Level 2
Assets at fair value
Nuclear decommissioning trusts	0	0
SCE \| Fair Value, Measurements, Recurring \| Stocks \| Level 3
Assets at fair value
Nuclear decommissioning trusts	0	0
SCE \| Fair Value, Measurements, Recurring \| Fixed Income
Assets at fair value
Nuclear decommissioning trusts	2,762	2,666
SCE \| Fair Value, Measurements, Recurring \| Fixed Income \| Level 1
Assets at fair value
Nuclear decommissioning trusts	738	1,001
SCE \| Fair Value, Measurements, Recurring \| Fixed Income \| Level 2
Assets at fair value
Nuclear decommissioning trusts	2,024	1,665
SCE \| Fair Value, Measurements, Recurring \| Fixed Income \| Level 3
Assets at fair value
Nuclear decommissioning trusts	0	0
SCE \| Fair Value, Measurements, Recurring \| Short-term investments, primarily cash equivalents
Assets at fair value
Nuclear decommissioning trusts	146	215
SCE \| Fair Value, Measurements, Recurring \| Short-term investments, primarily cash equivalents \| Level 1
Assets at fair value
Nuclear decommissioning trusts	98	120
SCE \| Fair Value, Measurements, Recurring \| Short-term investments, primarily cash equivalents \| Level 2
Assets at fair value
Nuclear decommissioning trusts	48	95
SCE \| Fair Value, Measurements, Recurring \| Short-term investments, primarily cash equivalents \| Level 3
Assets at fair value
Nuclear decommissioning trusts	$ 0	$ 0

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This element represents the percentage of equity investments located in United States.

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Interest and dividends receivables and receivables related to pending securities sales and payables related to pending securities purchases as of the balance sheet date.

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

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The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, and obligation to return cash collateral under master netting arrangements.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, and right to receive cash collateral under master netting arrangements.

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Fair value of asset after deduction of liability.

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Fair value of financial and nonfinancial obligations.

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Fair value portion of other assets.

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