Borrowings and Other Financing Instruments Other Equity (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividend Reinvestment Program [Line Items]
Proceeds from Issuance of Common Stock	$ 458	$ 230	$ 0
DividendReinvestmentProgram [Member]
Dividend Reinvestment Program [Line Items]
Proceeds from Issuance of Common Stock	$ 39	$ 39

The cash inflow from the additional capital contribution to the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

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