Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Accounts Receivable, Allowance for Credit Loss, Current	$ 10.1	$ 6.1	$ 1.0	$ 0.9
Cash and cash equivalents	70.1	54.0
Accounts Receivable, after Allowance for Credit Loss, Current	137.1	106.8
Inventories	73.8	70.5
Taxes applicable to subsequent years	67.8	137.1
Regulatory assets, current	97.2	82.0
Income Taxes Receivable, Current	21.7	27.1
Prepayments and other current assets	10.2	7.5
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(607.6)	(571.7)
Regulatory assets, non-current	131.4	140.0
Intangible assets, net of amortization	172.7	175.1
Other Assets, Noncurrent	36.2	45.9
Liabilities, Current	620.9	1,034.2
Current portion of long-term debt	310.2	704.4
Accounts payable	112.4	132.1
Accrued taxes	126.7	115.4
Accrued interest	14.0	22.8
Contract with Customer, Liability, Current	10.8	14.2
Regulatory liabilities, current	6.8	10.3
Other current liabilities	40.0	35.0
Long-term debt	1,426.1	1,425.6
Deferred Tax Liabilities, Net	222.8	249.6
Taxes payable	68.3	137.5
Regulatory liabilities, non-current	173.9	169.4
Pension, retiree and other benefits	23.5	30.7
Other deferred credits	7.8	8.3
Other paid-in capital	3,048.4	3,040.5
Accumulated other comprehensive income	14.7	(5.3)
Retained Earnings (Accumulated Deficit)	(2,669.7)	(2,673.1)
Liabilities	2,543.3	3,055.3
Property, Plant and Equipment, Net	$ 2,702.8	$ 2,571.4