Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net income	$ 23.1	$ 34.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	69.4	60.9
Amortization of Debt Issuance Costs and Discounts	2.6	2.9
Deferred income taxes	11.6	20.9
Gain (Loss) on Disposition of Business, Including Discontinued Operation	1.3	0.0
Public Utilities, Allowance for Funds Used During Construction, Additions	(5.4)	(3.8)
Changes in certain assets and liabilities:
Accounts receivable, net	(8.9)	6.8
Inventories	(17.2)	(11.2)
Taxes applicable to subsequent years	86.7	69.9
Current and non-current regulatory assets and liabilities	(7.6)	(67.8)
Prepayments and other current assets	(7.6)	(5.5)
Increase (Decrease) in Other Noncurrent Assets	14.7	3.7
Accounts payable	23.8	(36.4)
Accrued taxes payable / receivable	(116.5)	(71.9)
Accrued interest	8.3	6.8
Increase (Decrease) in Other Accrued Liabilities	22.0	15.5
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(6.2)	(7.1)
Other	(0.5)	(1.4)
Net Cash Provided by (Used in) Operating Activities	93.6	16.9
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(450.7)	(286.0)
Payments for (Proceeds from) Removal Costs	(21.9)	(16.0)
Payments for (Proceeds from) Other Investing Activities	(0.8)	0.2
Net cash used in investing activities	(473.4)	(301.8)
Cash flows from financing activities:
Payments of Deferred Finance Costs	(0.2)	(0.3)
Proceeds from Lines of Credit	355.0	205.0
Repayments of Lines of Credit	(325.0)	(240.0)
Proceeds from Short-Term Debt	150.0	0.0
Proceeds from Issuance of Long-term Debt	0.0	100.0
Net cash provided by financing activities	379.8	303.7
Cash, cash equivalents, and restricted cash:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0.0	18.8
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	41.1	49.4
Non-cash financing and investing activities:
Accruals for capital expenditures	37.4	46.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	54.0	47.2
Proceeds from Contributions from Parent	200.0	239.0
Subsidiaries [Member]
Cash flows from operating activities:
Net income	37.0	52.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	68.0	59.9
Amortization of Debt Issuance Costs and Discounts	1.1	1.3
Deferred income taxes	4.2	11.3
Gain (Loss) on Disposition of Business, Including Discontinued Operation	1.1	0.0
Public Utilities, Allowance for Funds Used During Construction, Additions	5.4	3.8
Changes in certain assets and liabilities:
Accounts receivable, net	(8.0)	7.9
Inventories	(15.8)	(11.2)
Taxes applicable to subsequent years	86.6	69.8
Current and non-current regulatory assets and liabilities	(7.6)	(67.8)
Prepayments and other current assets	(8.0)	(7.1)
Increase (Decrease) in Other Noncurrent Assets	16.4	4.1
Accounts payable	22.7	(37.3)
Accrued taxes payable / receivable	(100.2)	(77.1)
Accrued interest	8.5	7.1
Increase (Decrease) in Other Accrued Liabilities	21.4	15.3
Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits	(6.2)	(7.1)
Other	1.7	(0.3)
Net Cash Provided by (Used in) Operating Activities	117.5	17.8
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(449.6)	(283.4)
Payments for (Proceeds from) Removal Costs	(21.9)	(16.0)
Payments for (Proceeds from) Other Investing Activities	(0.7)	0.2
Net cash used in investing activities	(472.2)	(299.2)
Cash flows from financing activities:
Payments of Dividends	(21.0)	(65.0)
Payments of Deferred Finance Costs	(0.2)	(0.3)
Proceeds from Lines of Credit	355.0	205.0
Repayments of Lines of Credit	(325.0)	(205.0)
Proceeds from Short-Term Debt	150.0	0.0
Proceeds from Issuance of Long-term Debt	0.0	100.0
Net cash provided by financing activities	358.8	294.7
Cash, cash equivalents, and restricted cash:
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	4.1	13.3
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	19.7	33.1
Non-cash financing and investing activities:
Accruals for capital expenditures	37.4	46.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	27.2	19.2
Proceeds from Contributions from Parent	$ 200.0	$ 260.0