Operations and Significant Accounting Policies - Supplemental Statement of Cash Flows Information - USD ($) $ in Millions		9 Months Ended
		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.