Consolidated Statement of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating Activities [Abstract]
Net Income	$ 78.3	$ 67.3
AFUDC – Equity	(1.4)	(1.7)
Income from Equity Investments – Net of Dividends	0.2	0.6
Loss (Gain) on Investments and Property, Plant and Equipment	0.4	1.4
Depreciation Expense	125.0	122.7
Amortization of PSAs	(2.6)	(5.1)
Amortization of Other Intangible Assets and Other Assets	3.5	4.3
Deferred Income Tax Benefit	(12.9)	(12.3)
Share-Based and ESOP Compensation Expense	2.4	2.7
Defined Benefit Pension and Postretirement Benefit	(1.7)	(1.4)
Fuel Adjustment Clause	38.4	(18.8)
Bad Debt Expense	0.7	0.8
Provision for Interim Rate Refund	13.4	0.0
Residential Interim Rate Adjustment	0.0	(3.8)
Changes in Operating Assets and Liabilities [Abstract]
Accounts Receivable	14.0	8.2
Inventories	261.6	(168.2)
Prepayments and Other	(1.2)	(8.7)
Accounts Payable	(13.3)	17.8
Other Current Liabilities	(166.8)	(27.7)
Cash Contributions to Defined Benefit Pension Plans	(6.5)	0.0
Changes in Regulatory and Other Non-Current Assets	(1.6)	16.9
Changes in Regulatory and Other Non-Current Liabilities	1.7	(2.9)
Cash provided by (used in) Operating Activities	331.6	(7.9)
Investing Activities [Abstract]
Proceeds from Sale of Available-for-sale Securities	0.2	1.2
Payments for Purchase of Available-for-sale Securities	(0.4)	(1.2)
Payments to Acquire Businesses, Net of Cash Acquired	0.0	(155.0)
Payments for Equity Method Investments	(4.3)	(3.9)
Additions to Property, Plant and Equipment	(120.5)	(90.3)
Other Investing Activities	(6.3)	2.0
Cash used in Investing Activities	(131.3)	(247.2)
Financing Activities [Abstract]
Proceeds from Issuance of Common Stock	7.7	240.4
Equity Issuance Costs	0.0	(8.1)
Proceeds from Issuance of Short-Term and Long-Term Debt	403.7	465.3
Repayments of Short-Term and Long-Term Debt	(531.5)	(491.6)
Proceeds from Non-controlling Interest in Subsidiaries - Net	9.9	155.7
Dividends on Common Stock	(77.6)	(71.5)
Other Financing Activities	(1.6)	(1.1)
Cash provided by (used in) Financing Activities	(189.4)	289.1
Change in Cash, Cash Equivalents and Restricted Cash	10.9	34.0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 51.1	$ 81.7