Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Cash flows from operating activities:
Net income	$ 2.7	$ 2.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	29.2	22.6
Amortization of Debt Issuance Costs and Discounts	0.9	0.9
Deferred income taxes	3.3	5.7
Gain (Loss) on Disposition of Business, Including Discontinued Operation	0.0	1.3
Public Utilities, Allowance for Funds Used During Construction, Additions	0.0	(1.8)
Changes in certain assets and liabilities:
Accounts receivable, net	(24.6)	(7.3)
Inventories	(1.6)	(7.5)
Taxes applicable to subsequent years	35.3	29.6
Current and non-current regulatory assets and liabilities	5.7	(0.2)
Prepayments and other current assets	(3.8)	(0.7)
Increase (Decrease) in Other Noncurrent Assets	(0.9)	2.3
Accounts payable	30.6	6.6
Accrued taxes payable / receivable	(57.0)	(53.2)
Accrued interest	2.9	8.9
Increase (Decrease) in Other Accrued Liabilities	12.0	6.9
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	0.2	(7.0)
Other	0.0	(0.2)
Net Cash Provided by (Used in) Operating Activities	34.9	9.5
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(85.3)	(174.6)
Payments for (Proceeds from) Removal Costs	(1.0)	(6.0)
Payments for (Proceeds from) Other Investing Activities	(0.4)	(0.7)
Net cash used in investing activities	(86.7)	(181.3)
Cash flows from financing activities:
Proceeds from (Payments for) Other Financing Activities	1.0	0.0
Proceeds from Lines of Credit	135.0	185.0
Repayments of Lines of Credit	(55.0)	(30.0)
Net cash provided by financing activities	79.0	155.0
Cash, cash equivalents, and restricted cash:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	27.2	(16.8)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	81.3	24.3
Non-cash financing and investing activities:
Accruals for capital expenditures	40.9	55.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	20.7	11.1
Subsidiaries [Member]
Cash flows from operating activities:
Net income	10.7	9.4
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28.8	22.1
Amortization of Debt Issuance Costs and Discounts	0.4	0.4
Deferred income taxes	1.7	2.3
Gain (Loss) on Disposition of Business, Including Discontinued Operation	0.0	1.1
Public Utilities, Allowance for Funds Used During Construction, Additions	0.0	1.8
Changes in certain assets and liabilities:
Accounts receivable, net	(24.6)	(7.6)
Inventories	(1.7)	(7.0)
Taxes applicable to subsequent years	35.3	29.5
Current and non-current regulatory assets and liabilities	5.7	(0.2)
Prepayments and other current assets	(3.2)	0.6
Increase (Decrease) in Other Noncurrent Assets	(0.9)	2.3
Accounts payable	29.9	4.9
Accrued taxes payable / receivable	(54.1)	(49.0)
Accrued interest	3.2	9.2
Increase (Decrease) in Other Accrued Liabilities	11.1	7.0
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	0.2	(7.0)
Other	0.7	0.7
Net Cash Provided by (Used in) Operating Activities	43.2	16.9
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(85.3)	(173.1)
Payments for (Proceeds from) Removal Costs	(1.0)	(6.0)
Payments for (Proceeds from) Other Investing Activities	(0.4)	(0.7)
Net cash used in investing activities	(86.7)	(179.8)
Cash flows from financing activities:
Proceeds from Lines of Credit	135.0	185.0
Repayments of Lines of Credit	(55.0)	(30.0)
Net cash provided by financing activities	79.3	155.0
Cash, cash equivalents, and restricted cash:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	35.8	(7.9)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	60.5	7.7
Non-cash financing and investing activities:
Accruals for capital expenditures	40.8	56.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	$ 11.5	$ 1.9