XML 55 R43.htm IDEA: XBRL DOCUMENT
v3.21.2

Borrowings and Other Financing Instruments Forward Equity Agreement (Details) - USD ($) $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2021 | Sep. 30, 2020
Forward Contract Indexed to Issuer's Equity [Line Items] |  |
Proceeds from issuance of common stock | $ 13 | $ 5
Dividend Reinvestment Program |  |
Forward Contract Indexed to Issuer's Equity [Line Items] |  |
Proceeds from issuance of common stock | $ 38 | $ 30

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow from the additional capital contribution to the entity. + References 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=121586364&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | xel_ShareIssuanceProgramAxis=xel_DividendReinvestmentProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |