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Borrowings and Other Financing Instruments Borrowings and Other Financing Instruments, Long-Term Borrowings and Other Financing Instruments (Details) - USD ($) shares in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Nov. 30, 2018
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Less current maturities | $ 406.0 | $ 457.0 |  |
Long-term debt, noncurrent | 15,803.0 | 14,520.0 |  |
Amount outstanding at period end | 1,038.0 | 814.0 |  |
2019 | 406.0 |  |  |
2020 | 1,257.0 |  |  |
2021 | 425.0 |  |  |
2022 | 902.0 |  |  |
2023 | 653.0 |  |  |
Proceeds from issuance of common stock | $ 230.0 | 0.0 | $ 0.0 |
Forward Equity Agreements [Member] |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Maturity Date | Feb. 07, 2020 |  |  |
Common Stock, Value, to be Issued through Forward Equity Agreement |  |  |  | $ 459.0
Common Stock To Be Issued through forward Equity Agreement |  |  |  | 9.4
Period End Settlement Price, In Shares | 9.4 |  |  |
Period End Settlement Price, in Cash | $ 456.0 |  |  |
Period End Net Cash Settlement Price | $ 24.0 |  |  |
Period End Net Share Settlement Price | 0.5 |  |  |
At-the-Market Offering [Member] |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Maximum Aggregate Gross Sales Price of Common Stock that Can Be Offered and Sold | $ 4.7 |  |  |
Proceeds from issuance of common stock | 224.7 |  |  |
Transaction fees | 1.9 |  |  |
DividendReinvestmentProgram [Member] |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Proceeds from issuance of common stock | 38.5 | 39.2 |  |
Minimum | Forward Equity Agreements [Member] |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
expected settlement price | 450.0 |  |  |
Maximum | Forward Equity Agreements [Member] |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
expected settlement price | $ 460.0 |  |  |
Senior Unsecured Notes | Series Due June 15, 2028 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.00% |  |  |
Xcel Energy Inc. |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Unamortized discount | $ (5.0) | (2.0) |  |
Unamortized debt expense | (21.0) | (20.0) |  |
Less current maturities | 2.0 | 2.0 |  |
Long-term debt, noncurrent | 3,316.0 | 2,818.0 |  |
Xcel Energy Inc. | Senior Unsecured Notes |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 3,400.0 | $ 2,900.0 |  |
Debt Instrument, Maturity Date Range, Start | May 15, 2020 |  |  |
Debt Instrument, Maturity Date Range, End | Sep. 15, 2041 |  |  |
Xcel Energy Inc. | Senior Unsecured Notes | Series Due June 15, 2028 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount | $ 500.0 |  |  |
Debt Instrument, Maturity Date | Jun. 15, 2028 |  |  |
Xcel Energy Inc. | Senior Unsecured Notes | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 2.40% | 1.20% |  |
Xcel Energy Inc. | Senior Unsecured Notes | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.50% | 6.50% |  |
Xcel Energy Inc. | Capital Lease Obligations |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Capital Lease Obligations | $ (60.0) | $ (62.0) |  |
Other Subsidiaries |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Less current maturities | (1.0) | (2.0) |  |
Long-term debt, noncurrent | 25.0 | 26.0 |  |
Other Subsidiaries | Various Eloigne Co. Affordable Housing Project Notes |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 26.0 | $ 28.0 |  |
Debt Instrument, Maturity Date Range, Start | Sep. 01, 2019 |  |  |
Debt Instrument, Maturity Date Range, End | Dec. 31, 2052 |  |  |
Other Subsidiaries | Various Eloigne Co. Affordable Housing Project Notes | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 0.00% | 0.00% |  |
Other Subsidiaries | Various Eloigne Co. Affordable Housing Project Notes | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.90% | 7.05% |  |
NSP-Minnesota |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Unamortized discount | $ (21.0) | $ (22.0) |  |
Unamortized debt expense | (42.0) | (45.0) |  |
Less current maturities | 0.0 | 0.0 |  |
Long-term debt, noncurrent | 4,937.0 | 4,933.0 |  |
NSP-Minnesota | First Mortgage Bonds |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 5,000.0 | 5,000.0 |  |
Debt Instrument, Maturity Date Range, Start | Aug. 15, 2020 |  |  |
Debt Instrument, Maturity Date Range, End | Sep. 15, 2047 |  |  |
NSP-Minnesota | First Mortgage Bonds | Series Due Sept. 15, 2047 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount |  | $ 600.0 |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 3.60% |  |
Debt Instrument, Maturity Date |  | Sep. 15, 2047 |  |
NSP-Minnesota | First Mortgage Bonds | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 2.15% | 2.15% |  |
NSP-Minnesota | First Mortgage Bonds | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 7.125% | 7.125% |  |
NSP-Wisconsin |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Unamortized discount | $ (3.0) | $ (3.0) |  |
Unamortized debt expense | (9.0) | (7.0) |  |
Less current maturities | 0.0 | 151.0 |  |
Long-term debt, noncurrent | 807.0 | 610.0 |  |
NSP-Wisconsin | First Mortgage Bonds |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 800.0 | 750.0 |  |
Debt Instrument, Maturity Date Range, Start | Jun. 15, 2024 |  |  |
Debt Instrument, Maturity Date Range, End | Sep. 01, 2048 |  |  |
NSP-Wisconsin | First Mortgage Bonds | Series Due September 1, 2048 [Member] |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount | $ 200.0 |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.20% |  |  |
Debt Instrument, Maturity Date | Sep. 01, 2048 |  |  |
NSP-Wisconsin | First Mortgage Bonds | Series Due Dec. 1, 2047 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount |  | $ 100.0 |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 3.75% |  |
Debt Instrument, Maturity Date |  | Dec. 01, 2047 |  |
NSP-Wisconsin | First Mortgage Bonds | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 3.30% | 3.30% |  |
NSP-Wisconsin | First Mortgage Bonds | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.375% | 6.375% |  |
NSP-Wisconsin | City of La Crosse Resource Recovery Bond |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 19.0 | $ 19.0 |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.00% | 6.00% |  |
Debt Instrument, Maturity Date | Nov. 01, 2021 |  |  |
NSP-Wisconsin | Other |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 0.0 | $ 2.0 |  |
PSCo |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Unamortized discount | (14.0) | (13.0) |  |
Unamortized debt expense | (33.0) | (29.0) |  |
Less current maturities | 406.0 | 306.0 |  |
Long-term debt, noncurrent | 4,592.0 | 4,303.0 |  |
PSCo | First Mortgage Bonds |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 4,900.0 | 4,500.0 |  |
Debt Instrument, Maturity Date Range, Start | Jun. 01, 2019 |  |  |
Debt Instrument, Maturity Date Range, End | Jun. 15, 2048 |  |  |
PSCo | First Mortgage Bonds | Series Due June 15, 2028 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount | $ 350.0 |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 3.70% |  |  |
Debt Instrument, Maturity Date | Jun. 15, 2028 |  |  |
PSCo | First Mortgage Bonds | Series Due June 15, 2048 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount | $ 350.0 |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.10% |  |  |
Debt Instrument, Maturity Date | Jun. 15, 2048 |  |  |
PSCo | First Mortgage Bonds | Series Due June 15, 2047 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount |  | $ 400.0 |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 3.80% |  |
Debt Instrument, Maturity Date |  | Jun. 15, 2047 |  |
PSCo | First Mortgage Bonds | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 2.25% | 2.25% |  |
PSCo | First Mortgage Bonds | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.50% | 6.50% |  |
PSCo | Capital Lease Obligations |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Capital Lease Obligations | $ 145.0 | $ 151.0 |  |
Debt Instrument, Maturity Date Range, Start | Jan. 01, 2025 |  |  |
Debt Instrument, Maturity Date Range, End | Jan. 01, 2060 |  |  |
PSCo | Capital Lease Obligations | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 11.20% | 11.20% |  |
PSCo | Capital Lease Obligations | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 14.30% | 14.30% |  |
SPS |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Unamortized discount | $ (4.0) | $ (2.0) |  |
Unamortized debt expense | (20.0) | (18.0) |  |
Less current maturities | 0.0 | 0.0 |  |
Long-term debt, noncurrent | 2,126.0 | 1,830.0 |  |
SPS | Senior Unsecured Notes |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 350.0 | $ 350.0 |  |
Debt Instrument, Maturity Date Range, Start | Oct. 01, 2033 |  |  |
Debt Instrument, Maturity Date Range, End | Oct. 01, 2036 |  |  |
SPS | Senior Unsecured Notes | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.00% | 6.00% |  |
SPS | Senior Unsecured Notes | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.00% | 8.75% |  |
SPS | First Mortgage Bonds |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Long-term Debt, Gross | $ 1,800.0 | $ 1,500.0 |  |
Debt Instrument, Maturity Date Range, Start | Jun. 15, 2024 |  |  |
Debt Instrument, Maturity Date Range, End | Jan. 01, 2048 |  |  |
SPS | First Mortgage Bonds | Series Due June 15, 2048 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount | $ 300.0 |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.40% |  |  |
Debt Instrument, Maturity Date | Nov. 15, 2048 |  |  |
SPS | First Mortgage Bonds | Series Due August 15, 2047 |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Face Amount |  | $ 450.0 |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 3.70% |  |
Debt Instrument, Maturity Date |  | Aug. 15, 2047 |  |
SPS | First Mortgage Bonds | Minimum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 3.30% | 3.30% |  |
SPS | First Mortgage Bonds | Maximum |  |  |  |
Long-Term Borrowings and Other Financing Instruments |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.50% | 4.50% |  |

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- Definition Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- 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
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- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
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- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 + Details
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