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Operations and Significant Accounting Policies - Supplemental Statement of Cash Flows Information - USD ($) $ in Millions | 9 Months Ended
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Sep. 30, 2022 | Sep. 30, 2021
Supplemental Cash Flow Information [Abstract] |  |  |
Cash Paid for Interest – Net of Amounts Capitalized |  | $ 60.5 | $ 54.9
Noncash Investing and Financing Activities [Abstract] |  |  |
Increase (Decrease) in Accounts Payable for Capital Additions to Property, Plant and Equipment |  | 2.4 | (12.1)
Reclassification of Property, Plant and Equipment to Inventory | [1] | 99.8 | 0.0
Capitalized Asset Retirement Costs |  | 9.0 | 3.5
AFUDC–Equity |  | $ 2.4 | $ 1.7
[1] | The decommissioning of the existing Northern Wind assets resulted in a reclassification from Property, Plant and Equipment – Net to Inventories – Net in the second quarter of 2022 as they are being sold to a subsidiary of Xcel Energy Inc. In the third quarter of 2022, safe harbor equipment was transferred to the project entity resulting in an additional reclassification from Property, Plant and Equipment - Net to Inventories - Net.

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- Definition The increase (decrease) during the reporting period in the capitalized cost of equity (based on assumed rate of return) and / or borrowed funds (based on interest rate) used to finance construction of regulated assets, which is expected to be recovered through rate adjustments. As a result of this capitalization, net income is increased. This element pertains to certain regulated industries, such as public utilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585 + Details
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- Definition Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=126999549&loc=d3e4297-108586 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 17 -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3367-108585 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 25 -Subparagraph (e) -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3536-108585 + Details
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