XML 50 R39.htm IDEA: XBRL DOCUMENT
v3.20.2

Borrowings and Other Financing Instruments Forward Equity Agreement (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Nov. 04, 2019
Forward Contract Indexed to Issuer's Equity [Line Items] |  |  |
Proceeds from issuance of common stock | $ 5 | $ 457 |
Forward Equity Agreements [Member] |  |  |
Forward Contract Indexed to Issuer's Equity [Line Items] |  |  |
Common Stock, Value, to be Issued through Forward Equity Agreement |  |  | $ 743
Common Stock, Shares to be Issued through forward Equity Agreement |  |  | 11.8
Common shares, price per share used in forward calculation |  |  | $ 62.69
Common stock, interest rate spread used in forward calculation |  |  | 0.75%
Period End Settlement Price, In Shares |  |  | 11.8
Period End Settlement Price, in Cash |  |  | $ 722
Period End Net Cash Settlement Price |  |  | $ 92
Period End Net Share Settlement Price |  |  | 1.3
Common stock, initial shares in an agreement |  |  | 10.3
Common stock, additional shares in an agreement |  |  | 1.5
Forward Equity Agreements [Member] | Maximum [Member] |  |  |
Forward Contract Indexed to Issuer's Equity [Line Items] |  |  |
Expected settlement price | 720 |  |
Dividend Reinvestment Program [Member] |  |  |
Forward Contract Indexed to Issuer's Equity [Line Items] |  |  |
Proceeds from issuance of common stock | $ 30 | $ 29 |

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
- Definition Common Stock, Shares, to be issued through Forward Equity Agreement + References No definition available. + Details
Name: | xel_CommonStockSharestobeIssuedthroughforwardEquityAgreement
Namespace Prefix: | xel_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Stock, Value, to be Issued through Forward Equity Agreement + References No definition available. + Details
Name: | xel_CommonStockValuetobeIssuedthroughForwardEquityAgreement
Namespace Prefix: | xel_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Common shares, price per share used in forward calculation + References No definition available. + Details
Name: | xel_Commonsharespricepershareusedinforwardcalculation
Namespace Prefix: | xel_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common stock, additional shares in an agreement + References No definition available. + Details
Name: | xel_Commonstockadditionalsharesinanagreement
Namespace Prefix: | xel_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common stock, initial shares in an agreement + References No definition available. + Details
Name: | xel_Commonstockinitialsharesinanagreement
Namespace Prefix: | xel_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common stock, interest rate spread used in forward calculation + References No definition available. + Details
Name: | xel_Commonstockinterestratespreadusedinforwardcalculation
Namespace Prefix: | xel_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition expected settlement price + References No definition available. + Details
Name: | xel_Expectedsettlementprice
Namespace Prefix: | xel_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Period End Net Cash Settlement Price + References No definition available. + Details
Name: | xel_PeriodEndNetCashSettlementPrice
Namespace Prefix: | xel_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Period End Net Share Settlement Price + References No definition available. + Details
Name: | xel_PeriodEndNetShareSettlementPrice
Namespace Prefix: | xel_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period End Settlement Price, In Shares + References No definition available. + Details
Name: | xel_PeriodEndSettlementPriceInShares
Namespace Prefix: | xel_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period End Settlement Price, in Cash + References No definition available. + Details
Name: | xel_PeriodEndSettlementPriceinCash
Namespace Prefix: | xel_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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