Investments (Nuclear Decommissioning Trusts) (Details) - SCE - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Unrealized holding gains, net of losses	$ 1,500	$ 1,400
Deferred income taxes related to unrealized gains	348
Nuclear decommissioning trusts	$ 3,900

Amount before tax of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant