Commitments And Contingencies (Loss Accrual) (Details) - Butte Fire [Member] - Loss Accrual [Member] $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Balance at December 31, 2015	$ 0
Accrued losses	750
Payments	(60)
Balance at December 31, 2016	$ 690

The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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