NiSource (NI) 10-K 12 Feb 25 2024 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2024	Feb. 05, 2025	Jun. 30, 2024
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2024
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-16189
Entity Registrant Name	NiSource Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	35-2108964
Entity Address, Address Line One	801 East 86th Avenue
Entity Address, City or Town	Merrillville,
Entity Address, State or Province	IN
Entity Address, Postal Zip Code	46410
City Area Code	(877)
Local Phone Number	647-5990
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 13,022,151,904
Entity Common Stock, Shares Outstanding		469,939,639
Entity Central Index Key	0001111711
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Financial Statement Error Correction [Flag]	false
Documents Incorporated by Reference [Text Block]	Part III of this report incorporates by reference specific portions of the Registrant’s Notice of Annual Meeting and Proxy Statement relating to the Annual Meeting of Stockholders to be held on May 12, 2025.
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	NI
Security Exchange Name	NYSE

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2024
Auditor [Line Items]
Auditor Name	DELOITTE & TOUCHE LLP
Auditor Location	Columbus, Ohio
Auditor Firm ID	34

Statements Of Consolidated Inco

Statements Of Consolidated Income (Loss) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Revenues
Customer revenues	$ 5,282.9	$ 5,347.8	$ 5,738.6
Other revenues	172.2	157.6	112
Total Operating Revenues	5,455.1	5,505.4	5,850.6
Operating Expenses
Cost of energy	1,132.2	1,533.3	2,110.5
Operation and maintenance	1,515.2	1,494.9	1,489.4
Depreciation and amortization	1,043.2	908.2	820.8
Loss on impairment of assets	6.1	0	0
Loss (gain) on sale of assets, net	2.9	2.9	(104.2)
Other taxes	300	270.6	268.3
Total Operating Expenses	3,999.6	4,209.9	4,584.8
Operating Income	1,455.5	1,295.5	1,265.8
Other Income (Deductions)
Interest expense, net	(517.2)	(489.6)	(361.6)
Other, net	64.5	8	52.2
Total Other Deductions, Net	(452.7)	(481.6)	(309.4)
Income before Income Taxes	1,002.8	813.9	956.4
Income Taxes	158.1	139.5	164.6
Net Income	844.7	674.4	791.8
Net income (loss) attributable to noncontrolling interest	84.3	(39.9)	(12.3)
Net Income attributable to NiSource	760.4	714.3	804.1
Preferred dividends	(6.7)	(42.8)	(55.1)
Preferred redemption premium	14	9.8	0
Net Income Available to Common Shareholders	$ 739.7	$ 661.7	$ 749
Earnings Per Share
Basic Earnings Per Share	$ 1.63	$ 1.59	$ 1.84
Diluted Earnings Per Share	$ 1.62	$ 1.48	$ 1.70
Average common shares outstanding - Basic	454,200	416,100	407,100
Diluted Average Common Shares	456,000	447,900	442,700

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net Income		$ 844.7	$ 674.4	$ 791.8
Other comprehensive income:
Net unrealized gain (loss) on available-for-sale securities	[1]	3.3	3.9	(13.3)
Net unrealized gain (loss) on cash flow hedges	[2]	(0.4)	(0.2)	109.9
Unrecognized pension and OPEB benefit (costs)	[3]	0.3	(0.2)	(6.9)
Total other comprehensive income		3.2	3.5	89.7
Total Comprehensive Income		$ 847.9	$ 677.9	$ 881.5
[1] Net unrealized gain (loss) on available-for-sale securities, net of $0.9 million tax expense, $1.0 million tax expense and $3.5 million tax benefit in 2024, 2023 and 2022, respectively. Unrecognized pension and OPEB benefit (costs), net of $0.3 million tax expense, $0.1 million tax benefit and $2.3 million tax benefit in 2024, 2023 and 2022, respectively.

Statements of Consolidated Co_2

Statements of Consolidated Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	$ (0.9)	$ (1)	$ 3.5
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax, Parent	0.1	0.1	(36.4)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	$ (0.3)	$ 0.1	$ 2.3

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment
Plant		$ 34,152.9	$ 30,482.1
Accumulated depreciation and amortization		(8,699)	(8,207.2)
Net Property, Plant and Equipment	[1]	25,453.9	22,274.9
Investments and Other Assets
Unconsolidated affiliates		6.5	5.3
Available-for-sale debt securities (amortized cost of $91.9 and $169.0, allowance for credit losses of $0.1 and $0.6, respectively)		86.7	159.1
Other investments		85.5	82.7
Total Investments and Other Assets		178.7	247.1
Current Assets
Cash and cash equivalents		156.6	2,245.4
Restricted cash		42	35.7
Accounts receivable		987.9	884.9
Allowance for credit losses		(23.7)	(22.9)
Accounts receivable, net		964.2	862
Gas inventory		179.6	265.8
Materials and supplies, at average cost		173.3	172.1
Electric production fuel, at average cost		36.2	65.3
Exchange gas receivable		45.7	66
Regulatory assets		319.9	214.3
Deposits to renewable generation asset developer		0	454.2
Other Assets		138.5	105.5
Prepayments and other		24.2	13.1
Total Current Assets	[1]	2,080.2	4,499.4
Other Assets
Regulatory assets		2,157.4	2,245.9
Goodwill		1,485.9	1,485.9
Deferred charges and other		432	324
Total Other Assets		4,075.3	4,055.8
Total Assets		31,788.1	31,077.2
Stockholders' Equity
Common stock - $0.01 par value, 750,000,000 shares authorized; 469,822,472 and 447,381,671 shares outstanding, respectively		4.7	4.5
Preferred stock - $0.01 par value, 20,000,000 shares authorized; 0 and 40,000 shares outstanding, respectively		0	486.1
Treasury stock		(99.9)	(99.9)
Additional paid-in capital		9,521.5	8,879.5
Retained deficit		(711.7)	(967)
Accumulated other comprehensive loss		(30.4)	(33.6)
Total NiSource Stockholders' Equity		8,684.2	8,269.6
Noncontrolling interest in consolidated subsidiaries		1,984.1	1,866.7
Total Stockholders’ Equity		10,668.3	10,136.3
Long-term debt, excluding amounts due within one year		12,074.5	11,055.5
Total Capitalization		22,742.8	21,191.8
Current Liabilities
Current portion of long-term debt		1,281.2	23.8
Short-term borrowings		604.6	3,048.6
Accounts payable		863.1	749.4
Customer deposits and credits		268.8	294.4
Taxes accrued		173.4	166.2
Interest accrued		157	136.1
Asset retirement obligations		84.6	72.5
Exchange gas payable		91.8	50.5
Regulatory liabilities		150.5	278.6
Accrued compensation and employee benefits		268.2	227.6
Other accruals		170.2	217.4
Total Current Liabilities		4,113.4	5,265.1
Other Liabilities
Deferred income taxes		2,281.6	2,080.4
Accrued liability for postretirement and postemployment benefits		207.5	250.1
Regulatory liabilities		1,431.2	1,510.7
Asset retirement obligations		698.6	480.5
Other noncurrent liabilities		313	298.6
Total Other Liabilities(1)		4,931.9	4,620.3
Total Capitalization and Liabilities		$ 31,788.1	$ 31,077.2
[1] (1) Includes $1,323.8 million and $1,369.8 million in 2024 and 2023, respectively, of net property, plant and equipment assets, $65.0 million and $63.6 million in 2024 and 2023, respectively, of current assets of consolidated VIEs that may be used only to settle obligations of the consolidated VIEs. Refer to Note 4, "Noncontrolling Interests," for additional information.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Amortized Cost		$ 91.9	$ 169
Allowance for Credit Loss		(0.1)	(0.6)
Net Property, Plant and Equipment	[1]	25,453.9	22,274.9
Current assets	[1]	$ 2,080.2	$ 4,499.4
Common stock, par value		$ 0.01	$ 0.01
Common stock, shares authorized		750,000,000	750,000,000
Common stock, shares outstanding		469,822,472	447,381,671
Preferred Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01
Preferred Stock, Shares Authorized		20,000,000	20,000,000
Preferred Stock, Shares Outstanding		0	40,000
Current liabilities		$ 4,113.4	$ 5,265.1
Liabilities, Noncurrent		4,931.9	4,620.3
Deposits to renewable generation asset developer		0	454.2
Finance Lease, Liability, Payment, Due		429.4
Consolidated Variable Interest Entities
Net Property, Plant and Equipment		1,323.8	1,369.8
Current assets		65	63.6
Current liabilities		53.7	68.3
Liabilities, Noncurrent		$ 58.3	$ 55.7
[1] (1) Includes $1,323.8 million and $1,369.8 million in 2024 and 2023, respectively, of net property, plant and equipment assets, $65.0 million and $63.6 million in 2024 and 2023, respectively, of current assets of consolidated VIEs that may be used only to settle obligations of the consolidated VIEs. Refer to Note 4, "Noncontrolling Interests," for additional information.

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Activities
Net Income	$ 844.7	$ 674.4	$ 791.8
Adjustments to Reconcile Net Income to Net Cash from Operating Activities:
Depreciation and amortization	1,043.2	908.2	820.8
Deferred income taxes	168	134.1	156.9
Stock compensation expense and 401(k) profit sharing contribution	43.6	33.5	24.9
Loss (gain) on sale of assets	2.9	2.9	(105.3)
Payments for assets retirement obligations	(72.5)	(41.6)	(22.3)
Other adjustments	(52.8)	(17.9)	5.7
Changes in Assets and Liabilities:
Accounts receivable	(101.5)	184.1	(216.3)
Gas storage and other inventories	102	233.9	(258.9)
Accounts payable	71.5	(171.8)	165
Exchange gas receivable/payable	(133.5)	126.5	57.8
Other accruals	9.5	(102.9)	73.4
Prepayments and other current assets	(75.9)	36.7	(9.8)
Regulatory assets/liabilities	(8.7)	(26.2)	(129.4)
Postretirement and postemployment benefits	(64.3)	(22)	84.7
Deferred charges and other noncurrent assets	(20.8)	(10.1)	(4.1)
Other noncurrent liabilities and deferred credits	26.1	(6.7)	(25.5)
Net Cash Flows from Operating Activities	1,781.5	1,935.1	1,409.4
Investing Activities
Capital expenditures	(2,614)	(2,645.8)	(2,203.1)
Proceeds from Insurance Settlement, Investing Activities	0.8	3	105
Cost of removal	(166.8)	(160.8)	(151.7)
Purchases of available-for-sale securities	(17.8)	(42.8)	(73.5)
Sales of available-for-sale securities	93.2	39.9	75.7
Milestone and final payments to renewable generation asset developer	(482)	(761.4)	(323.9)
Advanced deposits for project costs	(29)	0	0
Other investing activities	2.6	(3.7)	1.3
Net Cash Flows used for Investing Activities	(3,213)	(3,571.6)	(2,570.2)
Financing Activities
Proceeds from issuance of long-term debt	2,229.5	1,488.7	345.6
Repayments of long-term debt and finance lease obligations	(25.6)	(33.1)	(60.3)
Repayment of short term credit agreements	(1,650)	0	0
Issuance of short term credit agreements	0	650	1,000
Net change in commercial paper and other short-term borrowings	(794)	636.4	202.2
Issuance of common stock, net of issuance costs	612.6	12.9	154.3
Redemption of preferred stock	(486.1)	(393.9)	0
Preferred stock redemption premium	(14)	(6.2)	0
Payment of obligation to renewable generation asset developer	0	(347.2)	0
Equity costs, premiums and other debt related costs	(67.3)	(30.2)	(13)
Contributions from NIPSCO minority interest holders	(99.5)	(2,161.9)	0
Distributions to NIPSCO minority interest holders	(50.3)	0	0
Distributions to tax equity partners	(50.3)	0	0
Contributions from tax equity partners	0	240.9	21.2
Distributions to tax equity partners	(16.1)	(14.1)	(6)
Dividends paid - common stock	(481)	(413.5)	(381.5)
Dividends paid - preferred stock	(8.2)	(43.8)	(55.1)
Contract liability payment	0	(66.6)	(66.1)
Net Cash Flows (used for) from Financing Activities	(651)	3,842.2	1,141.3
Change in cash, cash equivalents and restricted cash	(2,082.5)	2,205.7	(19.5)
Cash, cash equivalents and restricted cash at beginning of period	2,281.1	75.4	94.9
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 198.6	$ 2,281.1	$ 75.4

Statements Of Consolidated Ca_2

Statements Of Consolidated Cash Flows (Schedule of Balance Sheet Reconciliation) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash and Cash Equivalents, at Carrying Value	$ 156.6	$ 2,245.4	$ 40.8
Restricted cash	42	35.7	34.6
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 198.6	$ 2,281.1	$ 75.4	$ 94.9

Statements Of Consolidated Stoc

Statements Of Consolidated Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Preferred Stock		Treasury Stock, Common	Additional Paid-in Capital	Retained Deficit	Accumulated Other Comprehensive Loss	Noncontrolling Interest in Consolidated Subsidiaries
Beginning Balance at Dec. 31, 2021	$ 7,272.9	$ 4.1	$ 1,546.5	[1]	$ (99.9)	$ 7,204.3	$ (1,580.9)	$ (126.8)	$ 325.6
Comprehensive Income (Loss):
Net Income	791.8						804.1		(12.3)
Other Comprehensive Income (Loss), Net of Tax	89.7						0	89.7
Dividends:
Common stock	(381.7)						(381.7)
Preferred stock	55.1						55.1
Treasury Stock, Value, Acquired, Cost Method	19.1								(19.1)
Contribution from noncontrolling interest	(6)								6
Stock issuances:
Employee stock purchase plan	5.2					5.2
Long-term incentive plan	14.3					14.3
401(k) and profit sharing	9.7					9.7
ATM Program	141.9	0.1				141.8
Ending Balance at Dec. 31, 2022	$ 7,901.8	$ 4.2	$ 1,546.5	[1]	$ (99.9)	7,375.3	(1,213.6)	(37.1)	326.4
Stock issuances:
401(k) and profit sharing plan	337	337	0		0
ATM Program	5,942	5,942	0		0
Net Income	$ 674.4						714.3
Other Comprehensive Income (Loss), Net of Tax	3.5						0	3.5
Common stock	(414.1)						(414.1)
Preferred stock	43.8						43.8
Proceeds from (Payments to) Noncontrolling Interests	2,170.7					809.6			1,361.1
Contribution from noncontrolling interest	(233.2)								(233.2)
Distributions to Noncontrolling Interest Holders	14.1								14.1
Equity Units	0	$ 0.3	$ (666.5)	[1]		666.2
Employee stock purchase plan	5.9					5.9
Long-term incentive plan	12.6					12.6
401(k) and profit sharing	9.9					9.9
Ending Balance at Dec. 31, 2023	10,136.3	$ 4.5	486.1	[1]	$ (99.9)	8,879.5	(967)	(33.6)	1,866.7
Stock issuances:
Preferred stock redemption	393.9		$ 393.9	[1]
Preferred Stock Redemption Premium	$ (9.8)						9.8
401(k) and profit sharing plan	366	366	0		0
ATM Program	33,899	33,899	0		0
Stock Issued/Redeemed During the Period, Shares, Equity Units	0	0	(863)		0
Preferred Stock Shares Redeemed	0	0	(400)		0
Net Income	$ 844.7						760.4
Other Comprehensive Income (Loss), Net of Tax	3.2						0	3.2	0
Common stock	(483)						(483)
Preferred stock	8.1						8.1
Proceeds from (Payments to) Noncontrolling Interests	50.3
Contribution from noncontrolling interest	(99.5)						0		(99.5)
Distributions to Noncontrolling Interest Holders	66.4						0		66.4
Equity Units	(486.1)		$ (486.1)	[1]			0
Employee stock purchase plan	6.4					6.4
Long-term incentive plan	26.6					26.6
401(k) and profit sharing	9.2					9.2
ATM Program	600	$ 0.2				599.8
Ending Balance at Dec. 31, 2024	10,668.3	$ 4.7	$ 0	[1]	$ (99.9)	$ 9,521.5	(711.7)	$ (30.4)	$ 1,984.1
Stock issuances:
Preferred Stock Redemption Premium	$ (14)						$ (14)
401(k) and profit sharing plan	309	309	0		0
ATM Program	21,144	21,144	0		0
Preferred Stock Shares Redeemed	0	0	(40)		0
[1] Series A, Series B and Series C shares had an aggregate liquidation preference of $400M, $500M and $863M, respectively.

Statements Of Consolidated St_2

Statements Of Consolidated Stockholders' Equity (Shares) - shares shares in Thousands	Total	Common Stock	Treasury Stock, Common	Preferred Stock
Beginning Balance at Dec. 31, 2021	405,303	409,266	3,963	1,303
Issued:
Employee stock purchase plan	186	186	0	0
Long-term incentive plan	375	375	0	0
401(k) and profit sharing plan	337	337	0	0
ATM Program	5,942	5,942	0	0
Ending Balance at Dec. 31, 2022	412,143	416,106	3,963	1,303
Issued:
Equity Units	0	0	0	863
Preferred Stock Shares Redeemed	0	0	0	400
Employee stock purchase plan	216	216	0	0
Long-term incentive plan	758	758	0	0
401(k) and profit sharing plan	366	366	0	0
ATM Program	33,899	33,899	0	0
Ending Balance at Dec. 31, 2023	447,382	451,345	3,963	40
Issued:
Preferred Stock Shares Redeemed	0	0	0	40
Employee stock purchase plan	218	218	0	0
Long-term incentive plan	769	769	0	0
401(k) and profit sharing plan	309	309	0	0
ATM Program	21,144	21,144	0	0
Ending Balance at Dec. 31, 2024	469,822	473,785	3,963	0

Statements of Consolidated St_3

Statements of Consolidated Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Common Stock, Dividends, Per Share, Declared	$ 1.06	$ 1	$ 0.94
Series A Preferred Stock
Preferred Stock, Liquidation Preference, Value	$ 400	$ 400	$ 400
Series B Preferred Stock
Preferred Stock, Liquidation Preference, Value	500	$ 500	$ 500
Series C Preferred Stock
Preferred Stock, Liquidation Preference, Value	$ 863

Nature of Operations And Summar

Nature of Operations And Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations and Summary of Significant Accounting Policies	A. Company Structure and Principles of Consolidation. We are an energy holding company incorporated in Delaware and headquartered in Merrillville, Indiana. Our subsidiaries are fully regulated natural gas and electric utility companies serving approximately 3.8 million customers in six states. We generate substantially all of our operating income through these rate-regulated businesses. The consolidated financial statements include the accounts of us, our majority-owned subsidiaries, and VIEs of which we are the primary beneficiary after the elimination of all intercompany accounts and transactions. B. Use of Estimates. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. C. Cash, Cash Equivalents and Restricted Cash. We consider all highly liquid investments with original maturities of three months or less to be cash equivalents. We report amounts deposited in brokerage accounts for margin requirements as restricted cash. In addition, we have amounts deposited in trusts to satisfy requirements for the provision of various property, liability, workers compensation, and long-term disability insurance, and holdbacks related to certain joint venture development agreements which is classified as restricted cash on the Consolidated Balance Sheets and disclosed with cash and cash equivalents on the Statements of Consolidated Cash Flows. D. Accounts Receivable and Unbilled Revenue. Accounts receivable on the Consolidated Balance Sheets includes both billed and unbilled amounts. Unbilled amounts of accounts receivable relate to a portion of a customer’s consumption of gas or electricity from their last cycle billing date through the last day of the month (balance sheet date). Factors taken into consideration when estimating unbilled revenue include historical usage, customer rates, weather and reasonable and supportable forecasts. Accounts receivable fluctuates from year to year depending in large part on weather impacts and price volatility. Our accounts receivable on the Consolidated Balance Sheets include unbilled revenue, less reserves. The reserve for uncollectible receivables is our best estimate of the amount of probable credit losses in the existing accounts receivable. We determined the reserve based on historical collection experience, current market conditions and reasonable and supportable forecasts. Account balances are charged against the allowance when it is anticipated the receivable will not be recovered. Refer to Note 3, "Revenue Recognition," for additional information on customer-related accounts receivable, including amounts related to unbilled revenues. E. Investments in Debt Securities. Our investments in debt securities are carried at fair value and are designated as available-for-sale. These investments are included within “Available-for-sale debt securities” on the Consolidated Balance Sheets. Unrealized gains and losses, net of deferred income taxes, are recorded to accumulated other comprehensive income or loss. At each reporting period these investments are qualitatively and quantitatively assessed to determine whether a decline in fair value below the amortized cost basis has resulted from a credit loss or other factors. Impairments related to credit loss are recorded through an allowance for credit losses. Impairments that are not related to credit losses are included in other comprehensive income and are reflected in the Statements of Consolidated Income. No material impairment charges were recorded for the years ended December 31, 2024, 2023 or 2022. Refer to Note 14, "Fair Value," for additional information. F. Basis of Accounting for Rate-Regulated Subsidiaries. Rate-regulated subsidiaries account for and report assets and liabilities consistent with the economic effect of the way in which regulators establish rates, if the rates established are designed to recover the costs of providing the regulated service and it is probable that such rates can be billed and collected. Certain expenses and credits subject to utility regulation or rate determination that would normally be reflected in income for non-regulated entities are deferred on the Consolidated Balance Sheets and are later recognized in income as the related amounts are included in customer rates and recovered from or refunded to customers. We continually evaluate whether or not our operations are within the scope of ASC 980 and rate regulations. As part of that analysis, we evaluate probability of recovery for our regulatory assets. In management’s opinion, our regulated subsidiaries will be subject to regulatory accounting for the foreseeable future. Refer to Note 12, "Regulatory Matters," for additional information. G. Plant and Other Property and Related Depreciation and Maintenance. Property, plant and equipment (principally utility plant) is stated at cost. Our rate-regulated subsidiaries record depreciation using composite rates on a straight-line basis over the remaining service lives of the electric, gas and common properties, as approved by the appropriate regulators. Non-utility property, consisting of renewable generation assets owned by JVs of which we are the primary beneficiary and certain retired regulatory assets described below, is generally depreciated over the life of the associated assets. Refer to Note 9, "Property, Plant and Equipment," for additional information related to depreciation expense. For rate-regulated companies where provided for in rates, AFUDC is capitalized on all classes of property except organization costs, land, autos, office equipment, tools and other general property purchases. The allowance is applied to construction costs for that period of time between the date of the expenditure and the date on which such project is placed in service. Our consolidated pre-tax rate for AFUDC was 4.8% in 2024, 3.9% in 2023 and 3.4% in 2022. Generally, our subsidiaries follow the practice of charging maintenance and repairs, including the cost of removal of minor items of property, to expense as incurred. When our subsidiaries retire regulated property, plant and equipment, original cost plus the cost of retirement, less salvage value, is charged to accumulated depreciation. However, when it becomes probable a regulated asset will be retired substantially in advance of its original expected useful life or is abandoned, the cost of the asset and the corresponding accumulated depreciation is recognized as a separate asset. If the asset is still in operation, the gross amounts are classified as "Non-Utility and Other " as described in Note 9, "Property, Plant and Equipment." If the asset is no longer operating but still subject to recovery, the net amount is classified in "Regulatory assets" on the Consolidated Balance Sheets. If we are able to recover a full return of and on investment, the carrying value of the asset is based on historical cost. If we are not able to recover a full return on investment, a loss on impairment is recognized to the extent the net book value of the asset exceeds the present value of future revenues discounted at the incremental borrowing rate. External and internal costs associated with on-premise computer software developed for internal use are capitalized. Capitalization of such costs commences upon the completion of the preliminary stage of each project. Once the installed software is ready for its intended use, such capitalized costs are amortized on a straight-line basis generally over a period of five years. External and internal up-front implementation costs associated with cloud computing arrangements that are service contracts are deferred on the Consolidated Balance Sheets, with the associated internal-use software capitalized to plant if the we have a contractual right to take possession of the software at any time during the hosting period without significant penalty and it is feasible for us to either run the software on our own hardware or contract with another party unrelated to the vendor to host the software. Once the installed software is ready for its intended use, such deferred costs are amortized on a straight-line basis to "Operation and maintenance," over the minimum term of the contract plus contractually-provided renewal periods that are reasonably expected to be exercised. H. Goodwill and Other Intangible Assets. Substantially all of our goodwill relates to the excess of cost over the fair value of the net assets acquired in the Columbia acquisition on November 1, 2000. We test our goodwill for impairment annually as of May 1, or more frequently if events and circumstances indicate that goodwill might be impaired. Fair value of our reporting units is determined using a combination of income and market approaches. See Note 10, "Goodwill," for additional information. I. Accounts Receivable Transfer Programs. Certain of our subsidiaries have agreements with third parties to transfer certain accounts receivable without recourse. These transfers of accounts receivable are accounted for as secured borrowings. The entire gross receivables balance remains on the December 31, 2024 and 2023 Consolidated Balance Sheets. When amounts are securitized, the short-term debt is recorded in the amount of proceeds received from the transferees involved in the transactions. Refer to Note 7, "Short-Term Borrowings," for further information. J. Gas Cost and Fuel Adjustment Clause. Our regulated subsidiaries defer most differences between gas and fuel purchase costs and the recovery of such costs in revenues and adjust future billings for such deferrals on a basis consistent with applicable state-approved tariff provisions. These deferred balances are recorded as "Regulatory assets" or "Regulatory liabilities," as appropriate, on the Consolidated Balance Sheets. Refer to Note 12, "Regulatory Matters," for additional information. K. Gas Storage and Other Inventories. Both the LIFO inventory methodology and the weighted average cost methodology are used to value natural gas in storage, as approved by regulators for all of our regulated subsidiaries. Inventory valued using LIFO was $43.8 million and $43.9 million at December 31, 2024 and 2023, respectively. Based on the average cost of gas using the LIFO method, the estimated replacement cost of gas in storage was less than the stated LIFO cost by $12.8 million at December 31, 2024 and was less than the stated LIFO cost by $22.5 million at December 31, 2023. As all LIFO inventory costs are collected from customers through our rate-regulated subsidiaries, no inventory impairment has been recorded. Gas inventory valued using the weighted average cost methodology was $135.8 million at December 31, 2024 and $222.0 million at December 31, 2023. Electric production fuel is valued using the weighted average cost inventory methodology, as approved by NIPSCO's regulator. Materials and supplies are valued using the weighted average cost inventory methodology. Materials and supplies are charged to expense or capitalized to property, plant and equipment when issued. L. Accounting for Exchange and Balancing Arrangements of Natural Gas. Our Columbia Operations and NIPSCO Operations segment enters into balancing and exchange arrangements of natural gas as part of its operations and off-system sales programs. We record a receivable or payable for any of our respective cumulative gas imbalances, as well as for any gas inventory borrowed or lent under an exchange agreement. Exchange gas is valued based on individual regulatory jurisdiction requirements (for example, historical spot rate, spot at the beginning of the month). These receivables and payables are recorded as “Exchange gas receivable” or “Exchange gas payable” on our Consolidated Balance Sheets, as appropriate. M. Accounting for Risk Management Activities. We account for our derivatives and hedging activities in accordance with ASC 815. We recognize all derivatives as either assets or liabilities on the Consolidated Balance Sheets at fair value, unless such contracts are exempted as a normal purchase normal sale under the provisions of the standard. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and resulting designation. We do not offset the fair value amounts recognized for any of our derivative instruments against the fair value amounts recognized for the right to reclaim cash collateral or obligation to return cash collateral for derivative instruments executed with the same counterparty under a master netting arrangement. See Note 13, "Risk Management Activities," for additional information. N. Income Taxes and Investment Tax Credits. Under the asset and liability method, deferred income taxes are provided for the tax consequences of temporary differences by applying enacted statutory tax rates applicable to future years to differences between the financial statement carrying amount and the tax basis of existing assets and liabilities. Investment tax credits associated with regulated operations are deferred and amortized as a reduction to income tax expense over the estimated useful lives of the related properties. Furthermore, the tax basis of the asset is reduced by 50% of the ITCs received, resulting in a net deferred tax asset. To the extent certain deferred income taxes of the regulated companies are recoverable or payable through future rates, regulatory assets and liabilities have been established. Regulatory assets for income taxes are primarily attributable to property-related tax timing differences for which deferred taxes had not been provided in the past when regulators did not recognize such taxes as costs in the rate-making process. Regulatory liabilities for income taxes are primarily attributable to the regulated companies’ obligation to refund to ratepayers deferred income taxes provided at rates higher than the current Federal income tax rate. Such property-related amounts are credited to ratepayers using either the average rate assumption method or the reverse South Georgia method. Non property-related amounts are credited to ratepayers consistent with state utility commission direction. Pursuant to the Internal Revenue Code and relevant state taxing authorities, we and our subsidiaries file consolidated income tax returns for federal and certain state jurisdictions. We and our subsidiaries are parties to a tax sharing agreement. Income taxes recorded by each party represent amounts that would be owed had the party been separately subject to tax. O. Pension Remeasurement. We utilize a third-party actuary for the purpose of performing actuarial valuations of our defined benefit plans. Annually, as of December 31, we perform a remeasurement for our defined benefit plans. Quarterly, we monitor for significant events, and if a significant event is identified, we perform a qualitative and quantitative assessment to determine if the resulting remeasurement would materially impact the NiSource financial statements. If material, an interim remeasurement is performed. See Note 16, "Pension and Other Postemployment Benefits," for additional information. P. Environmental Expenditures. We accrue for costs associated with environmental remediation obligations, including expenditures related to asset retirement obligations and cost of removal, when the incurrence of such costs is probable and the amounts can be reasonably estimated, regardless of when the expenditures are actually made. The estimated future expenditures are based on currently enacted laws and regulations, existing technology and estimated site-specific costs where assumptions may be made about the nature and extent of site contamination, the extent of cleanup efforts, costs of alternative cleanup methods and other variables. The liability is adjusted as further information is discovered or circumstances change. The accruals for estimated environmental expenditures are recorded on the Consolidated Balance Sheets in “Other accruals” for short-term portions of these liabilities and “Other noncurrent liabilities and deferred credits” for the respective long-term portions of these liabilities. Rate-regulated subsidiaries applying regulatory accounting establish regulatory assets on the Consolidated Balance Sheets to the extent that future recovery of environmental remediation costs is probable through the regulatory process. Refer to Note 11, "Asset Retirement Obligations," and Note 19, "Other Commitments and Contingencies," for further information. Q. Excise Taxes. As an agent for some state and local governments, we invoice and collect certain excise taxes levied by state and local governments on customers and record these amounts as liabilities payable to the applicable taxing jurisdiction. Such balances are presented within "Other accruals" on the Consolidated Balance Sheets. These types of taxes collected from customers, comprised largely of sales taxes, are presented on a net basis affecting neither revenues nor cost of sales. We account for excise taxes for which we are liable by recording a liability for the expected tax with a corresponding charge to “Other taxes” expense on the Statements of Consolidated Income. R. Accrued Insurance Liabilities. We accrue for insurance costs related to workers compensation, automobile, property, general and employment practices liabilities based on the most probable value of each claim. In general, claim values are determined by professional, licensed loss adjusters who consider the facts of the claim, anticipated indemnification and legal expenses, and respective state rules. Claims are reviewed by us at least quarterly and an adjustment is made to the accrual based on the most current information. S. Noncontrolling Interest. We maintain a controlling financial interest in certain of our less than wholly owned subsidiaries. We consolidate these subsidiaries as either voting interest entities or VIEs and present the third-party investors' portion of our net income (loss), net assets and comprehensive income (loss) as noncontrolling interest. Noncontrolling interest is included as a component of equity on the Consolidated Balance Sheet. On December 31, 2023, the NIPSCO Minority Interest Transaction closed and a 19.9% equity interest in NIPSCO Holdings II, the sole owner of NIPSCO, was issued to an affiliate of Blackstone. NIPSCO Holdings II does not meet the criteria of a VIE and instead is consolidated under the voting interest model in accordance with ASC 810 as we maintain control through a majority interest in NIPSCO Holdings II. Refer to Note 4, "Noncontrolling Interests," for further discussion on the NIPSCO Minority Interest Transaction. We fund a portion of our renewable generation assets through JVs with tax equity partners. We consolidate these JVs in accordance with ASC 810 as they are VIEs in which we hold a variable interest, and we control decisions that are significant to the JVs' ongoing operations and economic results (i.e., we are the primary beneficiary). These JVs are subject to profit sharing arrangements in which the allocation of the JVs' cash distributions and tax benefits to members is based on factors other than members' relative ownership percentages. As such, we utilize the HLBV method to allocate proceeds to each partner at the balance sheet date based on the liquidation provisions of the related JV's operating agreement and adjust the amount of the VIE's net income attributable to us and the noncontrolling tax equity member during the period. In each reporting period, the application of HLBV to our consolidated VIEs results in a difference between the amount of profit from the consolidated JVs and the amount included in regulated rates. As discussed above in "F. Basis of Accounting for Rate-Regulated Subsidiaries," we are subject to the accounting and reporting requirements of ASC 980. In accordance with these principles, we recognize a regulatory liability or asset for amounts representing the timing difference between the profit earned from the JVs and the amount included in regulated rates to recover our approved investments in consolidated JVs. The amounts recorded in income will ultimately reflect the amount allowed in regulated rates to recover our investments over the useful life of the projects. The offset to the regulatory liability or asset associated with our renewable investments included in regulated rates is recorded in "Depreciation expense" on the Statements of Consolidated Income.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2024
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recent Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40) . This pronouncement requires disaggregated disclosure of income statement expenses for public business entities. The ASU requires disclosure in tabular format of disaggregation of relevant expense captions presented on the income statement by certain natural expense categories with certain related qualitative disclosures within the notes to the financial statements. The ASU does not change the expense captions an entity presents on the income statement. The ASU is effective for fiscal years beginning after December 15, 2026 and interim reporting periods beginning after December 15, 2027. We are currently evaluating the impacts this amendment will have on our required disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . This pronouncement enhances required income tax disclosures. The pronouncement will require disclosure of specific categories and reconciling items included in the rate reconciliation, disaggregation between federal, state and local income taxes paid, and disclosure of income taxes paid by jurisdictions over a certain threshold. Additionally, the pronouncement eliminates certain required disclosures related to unrecognized tax benefits. This ASU is effective for annual periods beginning after December 15, 2024, with early adoption permitted, and is to be applied on a prospective basis with retrospective application permitted. We will implement and provide the required disclosures beginning in 2025. Recently Adopted Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . This pronouncement enhances annual and interim disclosure requirements over reportable segments, primarily through enhanced disclosures about significant segment expenses. Specifically, the pronouncement requires disclosure of significant segment expenses that are regularly provided to the Chief Operating Decision Maker ("CODM") and included within each reported measure of segment profit or loss, disclosure of an amount for other segment items representing the difference between segment revenue and segment expenses already disclosed, disclosure of all required annual disclosures for interim periods and disclosure of title and position of the CODM and how the CODM uses reported measures. The pronouncement also allows for more than one measure of segment profit if the CODM uses more than one measure in assessing segment performance. This pronouncement is effective for annual periods beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024. The Company adopted this pronouncement as of December 31, 2024 with retrospective application and updated its disclosures to include significant expenses regularly provided to the CODM, the CODM's title and how the CODM utilizes reported measures. See Note 21, "Business Segment Information" for further discussion.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	Customer Revenues. Substantially all of our revenues are tariff-based. Under ASC 606, the recipients of our utility service meet the definition of a customer, while the operating company tariffs represent an agreement that meets the definition of a contract, which creates enforceable rights and obligations. Customers in certain of our jurisdictions participate in programs that allow for a fixed payment each month regardless of usage. Payments received that exceed the value of gas or electricity actually delivered are recorded as a liability and presented in "Customer deposits and credits" on the Consolidated Balance Sheets. Amounts in this account are reduced and revenue is recorded when customer usage exceeds payments received. We have identified our performance obligations created under tariff-based sales as 1) the commodity (natural gas or electricity, which includes generation and capacity) and 2) delivery. These commodities are sold and / or delivered to and generally consumed by customers simultaneously, leading to satisfaction of our performance obligations over time as gas or electricity is delivered to customers. Due to the at-will nature of utility customers, performance obligations are limited to the services requested and received to date. Once complete, we generally maintain no additional performance obligations. Transaction prices for each performance obligation are generally prescribed by each operating company’s respective tariff. Rates include provisions to adjust billings for fluctuations in fuel and purchased power costs and cost of natural gas. Revenues are adjusted for differences between actual costs, subject to reconciliation, and the amounts billed in current rates. Under or over recovered revenues related to these cost recovery mechanisms are included in "Regulatory assets" or "Regulatory liabilities" on the Consolidated Balance Sheets and are recovered from or returned to customers through adjustments to tariff rates. As we provide and deliver service to customers, revenue is recognized based on the transaction price allocated to each performance obligation. Distribution revenues are generally considered daily or "at-will" contracts as customers may cancel their service at any time (subject to notification requirements), and revenue generally represents the amount we are entitled to bill customers. In addition to tariff-based sales, our gas distribution in both our Columbia Operations and NIPSCO Operations segments enters into balancing and exchange arrangements of natural gas as part of our operations and off-system sales programs. Performance obligations for these types of sales include transportation and storage of natural gas and can be satisfied at a point in time or over a period of time, depending on the specific transaction. For those transactions that span a period of time, we record a receivable or payable for any cumulative gas imbalances, as well as for any gas inventory borrowed or lent under a gas distribution operations exchange agreement. Revenue Disaggregation and Reconciliation. We disaggregate revenue from contracts with customers based upon reportable segment, as well as by customer class. As of January 1, 2024, we have changed our reportable segments from Gas Distribution Operations and Electric Operations to Columbia Operations and NIPSCO Operations. Our historical segment disclosures have been recast to be consistent with the current presentation. For additional information see Note 21, "Business Segment Information". The Columbia Operations segment provides regulated natural gas service and transportation for residential, commercial and industrial customers in Ohio, Pennsylvania, Virginia, Kentucky, and Maryland. The NIPSCO Operations segment provides regulated gas and electric service in northern Indiana for residential, commercial and industrial customers. Other Revenues. As permitted by accounting principles generally accepted in the United States, regulated utilities have the ability to earn certain types of revenue that are outside the scope of ASC 606. These revenues primarily represent revenue earned under alternative revenue programs. Alternative revenue programs represent regulator-approved mechanisms that allow for the adjustment of billings and revenue for certain approved programs. We maintain a variety of these programs, including demand side management initiatives that recover costs associated with the implementation of energy efficiency programs, as well as normalization programs that adjust revenues for the effects of weather or other external factors. Additionally, we maintain certain programs with future test periods that operate similarly to FERC formula rate programs and allow for recovery of costs incurred to replace aging infrastructure. When the criteria to recognize alternative revenue have been met, we establish a regulatory asset and present revenue from alternative revenue programs on the Statements of Consolidated Income as “Other revenues”. When amounts previously recognized under alternative revenue accounting guidance are billed, we reduce the regulatory asset and record a customer account receivable. The tables below reconcile revenue disaggregation by customer class to segment revenue, as well as to revenues reflected on the Statements of Consolidated Income: Year Ended December 31, 2024 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Gas Distribution Residential $ 1,833.8 $ 531.4 $ — $ 2,365.2 Commercial 580.3 199.2 — 779.5 Industrial 144.2 79.0 — 223.2 Off-system 42.6 — — 42.6 Wholesale 1.2 — — 1.2 Miscellaneous (1) 26.3 15.4 — 41.7 Subtotal $ 2,628.4 $ 825.0 $ — $ 3,453.4 Electric Generation and Power Delivery Residential $ — $ 649.9 $ — $ 649.9 Commercial — 620.4 — 620.4 Industrial — 499.1 — 499.1 Wholesale — 38.3 — 38.3 Public Authority — 8.1 — 8.1 Miscellaneous (1) — 13.7 — 13.7 Subtotal $ — $ 1,829.5 $ — $ 1,829.5 Total Customer Revenues (2) 2,628.4 2,654.5 — 5,282.9 Other Revenues (3) 74.8 96.5 0.9 172.2 Total Operating Revenues $ 2,703.2 $ 2,751.0 $ 0.9 $ 5,455.1 (1) Amounts included in Columbia Operations are primarily related to earnings sharing mechanisms and late fees. Amounts included in NIPSCO Operations are primarily related to revenue refunds, public repairs and property rentals. (2) Customer revenue amounts exclude intersegment revenues. See Note 21, "Business Segment Information," for discussion of intersegment revenues. (3) Amounts included in Columbia Operations primarily relate to weather normalization adjustment mechanisms. Amounts included in NIPSCO Operations primarily relate to weather normalization adjustment mechanisms, MISO multi-value projects and revenue from non-jurisdictional transmission assets. Year Ended December 31, 2023 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Gas Distribution Residential $ 1,827.5 $ 635.0 $ — $ 2,462.5 Commercial 598.9 249.0 — 847.9 Industrial 139.0 87.0 — 226.0 Off-system 60.6 — — 60.6 Wholesale 1.6 — — 1.6 Miscellaneous (1) 33.4 14.8 — 48.2 Subtotal 2,661.0 985.8 — 3,646.8 Electric Generation and Power Delivery Residential — 583.9 — 583.9 Commercial — 578.1 — 578.1 Industrial — 474.1 — 474.1 Wholesale — 32.0 — 32.0 Public Authority — 11.5 — 11.5 Miscellaneous (1) — 21.4 — 21.4 Subtotal — 1,701.0 — 1,701.0 Total Customer Revenues (2) $ 2,661.0 $ 2,686.8 $ — $ 5,347.8 Other Revenues (3) 72.9 83.9 0.8 157.6 Total Operating Revenues $ 2,733.9 $ 2,770.7 $ 0.8 $ 5,505.4 (1) Amounts included in Columbia Operations are primarily related to earnings sharing mechanisms and late fees. Amounts included in NIPSCO Operations are primarily related to late fees, property rentals, revenue refunds, and adjustments. (2) Customer revenue amounts exclude intersegment revenues. See Note 21, "Business Segment Information," for discussion of intersegment revenues. (3) Amounts included in Columbia Operations primarily related to weather normalization adjustment mechanisms. Amounts included in NIPSCO Operations primarily related to MISO multi-value projects and revenue from non-jurisdictional transmission assets. Year Ended December 31, 2022 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Gas Distribution Residential $ 1,918.2 $ 691.5 $ — $ 2,609.7 Commercial 672.2 267.4 — 939.6 Industrial 135.5 85.1 — 220.6 Off-system 192.9 — — 192.9 Wholesale 2.1 — — 2.1 Miscellaneous (1) 27.3 10.9 — 38.2 Subtotal $ 2,948.2 $ 1,054.9 $ — $ 4,003.1 Electric Generation and Power Delivery Residential $ — $ 592.4 $ — $ 592.4 Commercial — 571.0 — 571.0 Industrial — 560.6 — 560.6 Wholesale — 13.5 — 13.5 Public Authority — 12.1 — 12.1 Miscellaneous (1) — (14.1) — (14.1) Subtotal $ — $ 1,735.5 $ — $ 1,735.5 Total Customer Revenues (2) $ 2,948.2 $ 2,790.4 $ — $ 5,738.6 Other Revenues (3) 3.7 95.8 12.5 112.0 Total Operating Revenues $ 2,951.9 $ 2,886.2 $ 12.5 $ 5,850.6 (1) Amounts included in Columbia Operations are primarily related to earnings share mechanisms and late fees. Amounts included in NIPSCO Operations are primarily related to revenue trackers, late fees and property rentals.2.1 (2) Customer revenue amounts exclude intersegment revenues. See Note 21, "Business Segment Information," for discussion of intersegment revenues. (3) Amounts included in Columbia Operations primarily related to weather normalization adjustment mechanisms. Amounts included in NIPSCO Operations primarily related to MISO multi-value projects and revenue from non-jurisdictional transmission assets. Amounts included in Corporate and Other primarily related to the Transition Services Agreement entered into in connection with the sale of the Massachusetts Business. Customer Accounts Receivable. Accounts receivable on our Consolidated Balance Sheets includes both billed and unbilled amounts, as well as certain amounts that are not related to customer revenues. Unbilled amounts of accounts receivable relate to a portion of a customer’s consumption of gas or electricity from the date of their last cycle billing through the last day of the month (balance sheet date). Factors taken into consideration when estimating unbilled revenue include historical usage, customer rates, and weather. A significant portion of our operations are subject to seasonal fluctuations in sales. During the heating season, primarily from November through March, revenues and receivables from gas sales are more significant than in other months. The opening and closing balances of customer receivables for the year ended December 31, 2024, are presented in the table below. We had no significant contract assets or liabilities during the period. Additionally, we have not incurred any significant costs to obtain or fulfill contracts. (in millions) Customer Accounts Receivable, Billed (less reserve) Customer Accounts Receivable, Unbilled (less reserve) Balance as of December 31, 2023 $ 479.4 $ 337.6 Balance as of December 31, 2024 525.1 408.1 Utility revenues are billed to customers monthly on a cycle basis. We expect that substantially all customer accounts receivable will be collected following customer billing, as this revenue consists primarily of periodic, tariff-based billings for service and usage. We maintain common utility credit risk mitigation practices, including requiring deposits and actively pursuing collection of past due amounts. Our regulated operations also utilize certain regulatory mechanisms that facilitate recovery of bad debt costs within tariff-based rates, which provides further evidence of collectibility. It is probable that substantially all of the consideration to which we are entitled from customers will be collected upon satisfaction of performance obligations. Allowance for Credit Losses. To evaluate for expected credit losses, customer account receivables are pooled based on similar risk characteristics, such as customer type, geography, payment terms, and related macro-economic risks. Expected credit losses are established using a model that considers historical collections experience, current information, and reasonable and supportable forecasts. Internal and external inputs are used in our credit model including, but not limited to, energy consumption trends, revenue projections, actual charge-offs data, recoveries data, shut-offs, customer delinquencies, final bill data, and inflation. We continuously evaluate available information relevant to assessing collectability of current and future receivables. We evaluate creditworthiness of specific customers periodically or following changes in facts and circumstances. When we become aware of a specific commercial or industrial customer's inability to pay, an allowance for expected credit losses is recorded for the relevant amount. We also monitor other circumstances that could affect our overall expected credit losses including, but not limited to, creditworthiness of overall population in service territories, adverse conditions impacting an industry sector, and current economic conditions. At each reporting period, we record expected credit losses to an allowance for credit losses account. When deemed to be uncollectible, customer accounts are written-off. A rollforward of our allowance for credit losses as of December 31, 2024 and December 31, 2023, are presented in the tables below: (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Balance as of January 1, 2024 $ 10.2 $ 11.9 $ 0.8 $ 22.9 Current period provisions 26.7 12.1 — 38.8 Write-offs charged against allowance (43.9) (11.0) (0.8) (55.7) Recoveries of amounts previously written off 16.8 0.9 — 17.7 Balance as of December 31, 2024 $ 9.8 $ 13.9 $ — $ 23.7 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Balance as of January 1, 2023 $ 11.1 $ 12.0 $ 0.8 $ 23.9 Current period provisions 28.3 11.5 — 39.8 Write-offs charged against allowance (49.2) (12.4) — (61.6) Recoveries of amounts previously written off 20.0 0.8 — 20.8 Balance as of December 31, 2023 $ 10.2 $ 11.9 $ 0.8 $ 22.9

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2024
Variable Interest Entities [Abstract]
Noncontrolling Interest Disclosure	Variable Interest Entities. A VIE is an entity in which the controlling interest is determined through means other than a majority voting interest. Refer to Note 1, "Nature of Operations and Summary of Significant Accounting Policies - S. Noncontrolling Interest," for information on our accounting policy for the VIEs. NIPSCO is the managing member and operator of two wind JVs, Rosewater and Indiana Crossroads Wind, which have 102 MW and 302 MW of nameplate capacity, respectively. NIPSCO is also a managing member and operator of two solar JVs, Indiana Crossroads Solar and Dunns Bridge I, which have a nameplate capacity of 200 MW and 265 MW, respectively. We have determined that these JVs are VIEs. NIPSCO controls decisions that are significant to these entities' ongoing operations and economic results. Therefore, we have concluded that NIPSCO is the primary beneficiary and have consolidated all four entities. Members of each respective JV include NIPSCO (who is the managing member) and a tax equity partner. Earnings, tax attributes and cash flows are allocated to both NIPSCO and the tax equity partner in varying percentages by category and over the life of the partnership. NIPSCO and each tax equity partner contributed cash to the respective JV. Once the tax equity partner has earned their negotiated rate of return and the JV has reached a stated contractual date, NIPSCO has the option to purchase the remaining interest in the respective JV from the tax equity partner. NIPSCO has an obligation to purchase 100% of the electricity generated by each commercially operational JV. We did not provide any financial or other support during the year that was not contractually required. Our Consolidated Balance Sheets included the following assets and liabilities associated with VIEs. (in millions) December 31, December 31, Net Property, Plant and Equipment $ 1,323.8 $ 1,369.8 Current assets 65.0 63.6 Total assets (1)(2) 1,388.8 1,433.4 Current liabilities 53.7 68.3 Asset retirement obligations 58.3 55.7 Finance lease obligations 40.4 — Total liabilities (1)(2) $ 152.4 $ 124.0 (1) The assets of each VIE represent assets of a consolidated VIE that can be used only to settle obligations of the respective consolidated VIE. The creditors of the liabilities of the VIEs do not have recourse to the general credit of the primary beneficiary. (2) In addition to the amounts disclosed above there is a de minimis amount of other noncurrent assets and liabilities at Rosewater as of December 31, 2024. Voting Interest Entities. On December 31, 2023, we consummated the NIPSCO Minority Interest Transaction for a capital contribution of $2.16 billion in cash. The difference between the $2.16 billion consideration received and the $1.36 billion carrying value of the noncontrolling interest claim on net assets was recorded to additional paid-in capital, net of $54.7 million

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Earnings Per Share	The calculations of basic and diluted EPS are based on the weighted average number of shares of common stock and potential common stock outstanding during the period. Diluted EPS includes the incremental effects of the various long-term incentive compensation plans and ATM forward sale agreements under the treasury stock method when the impact would be dilutive. For the purposes of determining diluted EPS, for the twelve months ended December 31, 2023 and 2022, the shares underlying the purchase contracts included within the Equity Units were included in the calculation of potential common stock outstanding using the if-converted method under US GAAP and we assumed share settlement of the remaining purchase contract payment balance from our Equity Units based on the average share price during the period. This method assumes conversion at the beginning of the reporting period, or at time of issuance, if later. The purchase contracts were settled on December 1, 2023. For the purchase contracts, the number of shares of our common stock that would have been issuable at the end of each reporting period prior to the settlement date were reflected in the denominator of our diluted EPS calculation. A numerator adjustment was reflected in the calculation of diluted EPS for interest expense incurred in 2023 and 2022, net of tax, related to the purchase contracts. We adopted ASU 2020-06 on January 1, 2022, which required us to assume share settlement of the remaining purchase contract payment balance from our Equity Units based on the average share price during the period. The shares underlying the Series C Mandatory Convertible Preferred Stock included within the Equity Units were contingently convertible as the conversion was contingent on a successful remarketing. Contingently convertible shares where conversion was not tied to a market price trigger were excluded from the calculation of diluted EPS until such time as the contingency had been resolved under the if-converted method. The unsuccessful remarketing resolved the contingency and no shares were reflected in the denominator for the years ended December 31, 2023 and 2022, for the calculation of diluted EPS. We began using the two-class method of computing earnings per share in 2023 because we have participating securities in the form of non-vested restricted stock units with a non-forfeitable right to dividend equivalents, for which vesting is predicated solely on the passage of time. The calculation of earnings per share using the two-class method excludes income attributable to these participating securities from the numerator and excludes the dilutive impact of those shares from the denominator. During 2022, we had no outstanding securities other than common and preferred stock, which required holders’ participation in dividends and earnings; therefore, we were not required to calculate EPS under the two-class method. Basic net income per share is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding during the period. Diluted net income per share is computed by giving effect to all potential shares of common stock, to the extent they are dilutive. Refer to Note 6, "Equity," for additional information. The following table presents the calculation of our basic and diluted EPS: Year Ended December 31, (in millions, except per share amounts) 2024 2023 2022 Numerator: Net Income Available to Common Shareholders $ 739.7 $ 661.7 $ 749.0 Less: Income allocated to participating securities 1.6 0.6 — Net Income Available to Common Shareholders - Basic $ 738.1 $ 661.1 $ 749.0 Add: Dilutive effect of Equity Units — 1.4 2.0 Net Income Available to Common Shareholders - Diluted $ 738.1 $ 662.5 $ 751.0 Denominator: Average common shares outstanding - Basic 454.2 416.1 407.1 Dilutive potential common shares: Equity Units purchase contracts — 29.8 30.2 Equity Units purchase contract payment balance — 0.9 3.2 Shares contingently issuable under employee stock plans 0.9 0.7 0.9 Shares restricted under employee stock plans 0.3 0.4 0.5 ATM Forward agreements 0.6 — 0.8 Average Common Shares - Diluted 456.0 447.9 442.7 Earnings per common share: Basic $ 1.63 $ 1.59 $ 1.84 Diluted $ 1.62 $ 1.48 $ 1.70

Equity

Equity	12 Months Ended
	Dec. 31, 2024
Equity [Abstract]
Equity	Holders of shares of our common stock are entitled to receive dividends when, as, and if declared by the Board out of funds legally available. The policy of the Board has been to declare cash dividends on a quarterly basis payable on or about the 20th day of February, May, August and November. We have certain debt covenants that could potentially limit the amount of dividends we could pay in order to maintain compliance with these covenants. Refer to Note 8, "Long-Term Debt," for more information. As of December 31, 2024, these covenants did not restrict the amount of dividends that were available to be paid. There is no preferred stock outstanding as of December 31, 2024. Common and preferred stock activity for 2024, 2023 and 2022 is described further below. ATM Program. In February 2024, we entered into eight separate equity distribution agreements pursuant to which we were able to sell up to an aggregate of $900.0 million of our common stock. In February 2024, under the ATM program, we executed a forward sale agreement, which allowed us to issue a fixed number of shares at a price to be settled in the future. The forward purchaser under our forward sale agreement borrowed 7,757,951 shares from third parties, which the forward purchaser sold, through its affiliated agent, at a weighted average price of $25.78 per share. On September 17, 2024 we settled all the shares under the forward sale agreement for $199.9 million, based on a net price of $25.77 per share. In May 2024, under the ATM program, we executed a forward sale agreement, which allowed us to issue a fixed number of shares at a price to be settled in the future. The forward purchaser under our forward sale agreement borrowed 10,390,000 shares from third parties, which the forward purchaser sold, through its affiliated agent, at a weighted average price of $28.87 per share. On September 11, 2024 we settled all the shares under the forward sale agreement for $299.1 million, based on a net price of $28.79 per share. In September 2024, under the ATM program, we executed a forward sale agreement, which allowed us to issue a fixed number of shares at a price to be settled in the future. The forward purchaser under our forward sale agreement borrowed 1,495,949 shares from third parties, which the forward purchaser sold, through its affiliated agent, at a weighted average price of $34.01 per share. On November 19, 2024 we settled all the shares under the forward sale agreement for $50.3 million, based on a net price of $33.64 per share. In September 2024, under the ATM program, we executed a second forward sale agreement, which allowed us to issue a fixed number of shares at a price to be settled in the future. The forward purchasers under our forward sale agreement borrowed 1,500,000 shares from third parties, which the forward purchaser sold, through its affiliated agent, at a weighted average price of $34.32 per share. On November 20, 2024 we settled all the shares under the forward sale agreement for$51.0 million, based on a net price of $33.99 per share. As of December 31, 2024, the ATM program had approximately $297.7 million of equity available for issuance. The program expires on December 31, 2025. Series A Preferred Stock. During 2023, there were $28.25 dividends declared per share for the Series A Preferred Stock. On June 15, 2023, we redeemed all 400,000 outstanding shares of Series A Preferred Stock for a redemption price of $1,000 per share or $400.0 million in total. Series B and B-1 Preferred Stock. During 2024 and 2023, dividends declared per share for the Series B Preferred Stock were $406.25 and $1,625.0, respectively. On March 15, 2024, we redeemed all 20,000 outstanding shares of Series B Preferred Stock for a redemption price of $25,000 per share and all 20,000 outstanding shares of Series B-1 Preferred Stock for a redemption price of $0.01 per share or $500.0 million in total. Following the redemption, dividends ceased to accrue on the shares of Series B Preferred Stock, shares of the Series B Preferred Stock and Series B-1 Preferred Stock were no longer deemed outstanding and all rights of the holders of such shares of Series B Preferred Stock and Series B-1 Preferred Stock terminated. In conjunction with the redemption, we recorded a $14.0 million preferred stock redemption premium, calculated as the difference between the carrying value on the redemption date of the Series B Preferred Stock and Series B-1 Preferred Stock and the total amount of consideration paid to redeem, which was recorded as a reduction to retained earnings during the first quarter of 2024. We did not recognize an excise tax liability under the IRA in connection with this redemption as we issued common stock in 2024 in excess of the fair value of the Series B Preferred Stock and Series B-1 Preferred Stock redeemed. In March 2024, we filed a Certificate of Elimination to our Amended and Restated Certificate of Incorporation with the Secretary of State of Delaware to eliminate from the Amended and Restated Certificate of Incorporation all matters set forth in the Certificate of Designations with respect to the Series B Preferred Stock and the Certificate of Designations with respect to the Series B-1 Preferred Stock. As a result, the 20,000 shares that were previously designated as Series B Preferred Stock and the 20,000 shares that were previously designated as Series B-1 Preferred Stock were returned to the status of authorized but unissued shares of preferred stock, par value $0.01 per share, without designation as to series. The Certificate of Elimination does not change the total number of authorized shares of capital stock of NiSource or the total number of authorized shares of preferred stock. We voluntarily delisted the preferred stock from the New York Stock Exchange on March 15, 2024. Equity Units. On December 1, 2023, we issued 33,898,837 shares of our common stock under the purchase contract component of the Corporate Units. As of December 1, 2023, each holder of Corporate Units was deemed to have automatically delivered to us the related Series C Mandatory Convertible Preferred Stock that were components of the Corporate Units in full satisfaction of such holder’s obligations under the related purchase contract, and all 862,500 shares of Series C Mandatory Convertible Preferred Stock were returned to the status of authorized but unissued preferred stock, par value of $0.01 per share, without designation as to series. We voluntarily delisted the Corporate Units from the New York Stock Exchange on December 1, 2023. Refer to Note 5, "Earnings Per Share," for additional information regarding our treatment of the Equity Units for diluted EPS. On October 21, 2024, we filed a Certificate of Elimination to our Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to eliminate from the Amended and Restated Certificate of Incorporation all matters set forth in the Certificate of Designations with respect to the Series C Mandatory Convertible Preferred Stock. Noncontrolling Interest in Consolidated Subsidiaries. As of December 31, 2024 and 2023, NIPSCO and tax equity partners have completed their cash contributions into the Indiana Crossroads Wind, Rosewater, Indiana Crossroads Solar and Dunns Bridge I JVs. Earnings, tax attributes and cash flows are allocated to both NIPSCO and the respective tax equity partners in varying percentages by category and over the life of the partnership. The tax equity partner's contributions, net of these allocations, is represented as a noncontrolling interest within total equity on the Consolidated Balance Sheets. Refer to Note 4, "Noncontrolling Interests," for more information. On December 31, 2023, we consummated the closing of the NIPSCO Minority Interest Transaction and issued a 19.9% equity interest in NIPSCO Holdings II LLC to BIP in exchange for a capital contribution of $2.16 billion in cash. Transaction costs and deferred tax impacts of $54.7 million and $63.5 million were recorded during the period ending December 31, 2023. Refer to Note 15, "Income Taxes," and Note 19, "Other Commitments and Contingencies - E. Other Matters," in the Notes to the Consolidated Financial Statements for more information on this transaction.

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2024
Short-Term Debt [Abstract]
Short-Term Borrowings	We generate short-term borrowings from our revolving credit facility, commercial paper program, accounts receivable transfer programs, and term credit agreements. Each of these borrowing sources is described further below. Revolving Credit Facility. We maintain a revolving credit facility to fund ongoing working capital requirements, including the provision of liquidity support for our commercial paper program, provide for issuance of letters of credit, and also for general corporate purposes. Our revolving credit facility has a program limit of $1.85 billion and is comprised of a syndicate of banks. At December 31, 2024 and 2023, we had no outstanding borrowings under this facility. Commercial Paper Program. At December 31, 2024 and December 31, 2023, our commercial paper program had a program limit of up to $1.85 billion and $1.50 billion, respectively. On February 9, 2024, we increased the program limit from $1.50 billion to $1.85 billion. We had $604.6 million and $1,061.0 million of commercial paper outstanding with weighted-average interest rates of 4.73% and 5.65% as of December 31, 2024 and 2023, respectively. Accounts Receivable Transfer Programs. Columbia of Ohio, NIPSCO, and Columbia of Pennsylvania each maintain a receivables agreement whereby they transfer their customer accounts receivables to third party financial institutions through consolidated special purpose entities. The three agreements expire between May 2025 and October 2025 and may be further extended if mutually agreed to by the parties thereto. All receivables transferred to third parties are valued at face value, which approximates fair value due to their short-term nature. The amount of the undivided percentage ownership interest in the accounts receivables transferred is determined in part by required loss reserves under the agreements. Transfers of accounts receivable are accounted for as secured borrowings resulting in the recognition of short-term borrowings on the Consolidated Balance Sheets. As of December 31, 2024, the maximum amount we could borrow related to our accounts receivable programs is $175.0 million. We had zero and $337.6 million short-term borrowings related to the securitization transactions as of December 31, 2024 and 2023, respectively. For the year ended December 31, 2024 and 2023, $337.6 million and $9.6 million, respectively, was recorded as cash flows used for financing activities related to the change in short-term borrowings due to securitization transactions. For the accounts receivable transfer programs, we pay used facility fees for amounts borrowed, unused commitment fees for amounts not borrowed, and upfront renewal fees. Fees associated with the securitization transactions were $1.5 million, $2.7 million, and $2.5 million for the years ended December 31, 2024, 2023 and 2022, respectively. Columbia of Ohio, NIPSCO and Columbia of Pennsylvania remain responsible for collecting the receivables securitized, and the receivables cannot be transferred to another party. Refer to Note 23, "Interest Expense, Net," for additional information on securitization transaction fees. Term Credit Agreements. At December 31, 2023, we had $1.0 billion, and $650.0 million outstanding under term credit agreements with interest rates of 6.41% and 6.50%, respectively. On January 3, 2024, we terminated and repaid in full our $1.0 billion and $650.0 million term credit agreements with proceeds from the NIPSCO Minority Interest Transaction. Items listed above, excluding the term credit agreements, are presented net in the Statements of Consolidated Cash Flows as their maturities are less than 90 days.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2024
Long-Term Debt, Current and Noncurrent [Abstract]
Long-Term Debt	Our long-term debt as of December 31, 2024 and 2023 is as follows: Long-term debt type Maturity as of December 31, 2024 Weighted average interest rate (%) Outstanding balance as of December 31, (in millions) 2024 2023 Senior notes: NiSource August 2025 0.950 % $ 1,250.0 $ 1,250.0 NiSource May 2027 3.490 % 1,000.0 1,000.0 NiSource December 2027 6.780 % 3.0 3.0 NiSource March 2028 5.250 % 1,050.0 1,050.0 NiSource July 2029 5.200 % 600.0 — NiSource September 2029 2.950 % 750.0 750.0 NiSource May 2030 3.600 % 1,000.0 1,000.0 NiSource February 2031 1.700 % 750.0 750.0 NiSource June 2033 5.400 % 450.0 450.0 NiSource April 2034 5.350 % 650.0 — NiSource December 2040 6.250 % 152.6 152.6 NiSource June 2041 5.950 % 347.4 347.4 NiSource February 2042 5.800 % 250.0 250.0 NiSource February 2043 5.250 % 500.0 500.0 NiSource February 2044 4.800 % 750.0 750.0 NiSource February 2045 5.650 % 500.0 500.0 NiSource May 2047 4.375 % 1,000.0 1,000.0 NiSource March 2048 3.950 % 750.0 750.0 NiSource June 2052 5.000 % 350.0 350.0 Total senior notes $ 12,103.0 $ 10,853.0 Junior subordinated notes: NiSource November 2054 6.950 % 500.0 — NiSource March 2055 6.375 % 500.0 — Total junior subordinated notes $ 1,000.0 $ — Medium term notes: NiSource May 2027 7.990 % $ 29.0 $ 29.0 NIPSCO June 2027 to August 2027 7.644 % 58.0 58.0 Columbia of Massachusetts December 2025 to February 2028 6.373 % 15.0 15.0 Total medium term notes $ 102.0 $ 102.0 Finance leases: NiSource Corporate Services January 2025 to September 2027 3.470 % $ 14.6 $ 30.5 NIPSCO December 2027 to November 2035 5.250 % 124.3 61.2 Columbia of Ohio December 2025 to March 2044 6.150 % 85.6 90.3 Columbia of Virginia July 2029 to November 2039 6.190 % 15.2 16.1 Columbia of Kentucky May 2027 5.360 % 0.1 0.2 Columbia of Pennsylvania July 2027 to May 2035 4.470 % 6.4 7.1 Total finance leases $ 246.2 $ 205.4 Less: Unamortized issuance costs and discounts (95.5) (81.1) Less: Current portion of long term debt (1,281.2) (23.8) Total Long-Term Debt $ 12,074.5 $ 11,055.5 Details of our 2024 long-term debt related activity are summarized below: • On March 14, 2024, we completed the issuance and sale of $650.0 million of 5.350% senior unsecured notes maturing in 2034, which resulted in approximately $642.6 million of net proceeds after discount and debt issuance costs. • On May 16, 2024, we completed the issuance and sale of $500.0 million of 6.950% fixed-to-fixed reset rate junior subordinated notes maturing in 2054, which resulted in approximately $493.4 million of net proceeds after debt issuance costs. The subordinated notes bear interest (i) from and including May 16, 2024 to, but excluding, November 30, 2029 at a rate of 6.950% per annum and (ii) from and including November 30, 2029, during each five-year reset period at a rate per annum equal to the five-year U.S. treasury rate (determined as described in the prospectus supplement dated May 13, 2024, which was filed with the SEC on May 14, 2024) as of the then most recent reset interest determination date plus a spread of 2.451%, to be reset on each reset date. At our option, we may redeem some or all of the subordinated notes during specified periods, and upon the occurrence of certain ratings or tax events, all as described in the prospectus supplement. In accordance with terms of the subordinated notes, we have the right, from time to time, to defer the payment of interest on the outstanding subordinated notes on one or more occasions for up to ten consecutive years. In the event that we were to exercise such right to defer interest on the subordinated notes, we would not be able to pay cash dividends on the common stock during the periods in which such payments were deferred. The subordinated notes were issued pursuant to a Subordinated Indenture, dated as of May 16, 2024, between us and The Bank of New York Mellon, as trustee, as supplemented by the First Supplemental Indenture thereto, dated as of May 16, 2024. • On June 24, 2024, we completed the issuance and sale of $600.0 million of 5.200% senior unsecured notes maturing in 2029, which resulted in approximately $593.7 million of net proceeds after discount and debt issuance costs. • On September 9, 2024, we completed the issuance and sale of $500.0 million of 6.375% fixed-to-fixed reset rate junior subordinated notes maturing in 2055, which resulted in approximately $493.6 million of net proceeds after debt issuance costs. The subordinated notes bear interest (i) from and including September 9, 2024 to, but excluding, March 31, 2035 at a rate of 6.375% per annum and (ii) from and including March 31, 2035, during each five-year reset period at a rate per annum equal to the five-year U.S. treasury rate (determined as described in the prospectus supplement dated September 3, 2024, which was filed with the SEC on September 4, 2024) as of the then most recent reset interest determination date plus a spread of 2.527%, to be reset on each reset date. At our option, we may redeem some or all of the subordinated notes during specified periods, and upon the occurrence of certain ratings or tax events, all as described in the prospectus supplement. In accordance with terms of the subordinated notes, we have the right, from time to time, to defer the payment of interest on the outstanding subordinated notes on one or more occasions for up to ten consecutive years. In the event that we were to exercise such right to defer interest on the subordinated notes, we would not be able to pay cash dividends on the common stock during the periods in which such payments were deferred. The subordinated notes were issued pursuant to a Subordinated Indenture, dated as of May 16, 2024, between us and The Bank of New York Mellon, as trustee, as supplemented by the Second Supplemental Indenture thereto, dated as of September 9, 2024. Details of our 2023 long-term debt related activity are summarized below: • On March 24, 2023, we completed the issuance sale of $750.0 million of 5.250% senior unsecured notes maturing in 2028, which resulted in approximately $742.2 million of net proceeds after discount and debt issuance costs. • On June 8, 2023, we completed the issuance and sale of $300.0 million of 5.250% senior unsecured notes maturing in 2028 (the "2028 Notes"). The terms of the 2028 Notes, other than the issue date and the price to the public, are identical to the terms of, and constitute as a reopening of, our 5.250% senior unsecured notes due 2028 issued on March 24, 2023. With the incremental issuance, we now have $1.05 billion of 5.250% senior unsecured notes maturing in 2028. On June 8, 2023, we also completed the issuance and sale of $450.0 million of 5.400% senior unsecured notes maturing in 2033. These issuances resulted in approximately $742.5 million of total net proceeds after discount and debt issuance costs. See Note 19, "Other Commitments and Contingencies - A. Contractual Obligations," for the outstanding long-term debt maturities at December 31, 2024. Unamortized debt expense, premium and discount on long-term debt applicable to outstanding bonds are being amortized over the life of such bonds. We are subject to a financial covenant under our revolving credit facility which requires us to maintain a debt to capitalization ratio that does not exceed 70%. As of December 31, 2024, the ratio was 52.6%. We are also subject to certain other non-financial covenants under the revolving credit facility. Such covenants include a limitation on the creation or existence of new liens on our assets, generally exempting liens on utility assets, purchase money security interests, preexisting security interests and an additional subset of assets equal to $200 million. An asset sale covenant generally restricts the sale, conveyance, lease, transfer or other disposition of our assets to those dispositions that are for a price not materially less than fair market of such assets, that would not materially impair our ability to perform obligations under the revolving credit facility, and that together with all other such dispositions, would not have a material adverse effect. The covenant also restricts dispositions to no more than 15% of our consolidated total assets on December 31, 2022. Additionally, the revolving credit facility requires us to own directly or indirectly at least 70% of NIPSCO. The revolving credit facility also includes a cross-default provision, which triggers an event of default under the credit facility in the event of an uncured payment default relating to any indebtedness of us or any of our subsidiaries in a principal amount of $75.0 million or more. Our indentures generally do not contain any financial maintenance covenants. However, our indentures are generally subject to cross-default provisions ranging from uncured payment defaults of $5.0 million to $50.0 million, and limitations on the incurrence of liens on our assets, generally exempting liens on utility assets, purchase money security interests, preexisting security interests and an additional subset of assets capped at 10% of our consolidated net tangible assets.

Property, Plant And Equipment

Property, Plant And Equipment	12 Months Ended
	Dec. 31, 2024
Property, Plant and Equipment [Abstract]
Property, Plant And Equipment	Our property, plant and equipment on the Consolidated Balance Sheets are classified as follows: At December 31, (in millions) 2024 2023 Property, Plant and Equipment Gas Distribution Utility $ 20,007.2 $ 18,154.5 Electric Utility 8,666.8 7,907.9 Corporate 248.1 274.2 Construction Work in Process 2,084.7 1,261.1 JV Renewable Generation Assets (1) 1,434.2 1,434.4 Non-Utility and Other 1,711.9 1,450.0 Total Property, Plant and Equipment $ 34,152.9 $ 30,482.1 Accumulated Depreciation and Amortization Gas Distribution Utility $ (4,166.8) $ (3,924.4) Electric Utility (2,707.8) (2,709.5) Corporate (163.4) (174.2) JV Renewable Generation Assets (1) (110.4) (64.5) Non-Utility and Other (1,550.6) (1,334.6) Total Accumulated Depreciation and Amortization $ (8,699.0) $ (8,207.2) Net Property, Plant and Equipment $ 25,453.9 $ 22,274.9 (1) These JV renewable generation assets owned and operated by JVs between NIPSCO and unrelated tax equity partners represent Non-Utility Property, are depreciated straight-line over 30 years and are part of our NIPSCO Operations segment. Refer to Note 4, "Noncontrolling Interests," for additional information. The weighted average depreciation provisions for utility plant, as a percentage of the original cost, for the periods ended December 31, 2024, 2023 and 2022 were as follows: 2024 2023 2022 NIPSCO Operations 3.0 % 3.0 % 2.7 % Columbia Operations 2.6 % 2.5 % 2.4 % We recognized depreciation expense of $820.4 million, $756.9 million and $685.0 million for the years ended 2024, 2023 and 2022, respectively. The 2024, 2023 and 2022, depreciation expense includes $58.9 million, $12.5 million, and $11.0 million related to the regulatory deferral of income associated with our JVs. See Note 1, "Nature of Operations and Summary of Significant Accounting Policies - S. Noncontrolling Interest," for additional details. Amortization of on-premise Software Costs. We amortized $85.2 million, $77.5 million and $53.1 million in 2024, 2023 and 2022, respectively, related to software recorded as intangible assets. Our unamortized software balance was $236.1 million and $205.6 million at December 31, 2024 and 2023, respectively. Amortization of Cloud Computing Costs.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill And Other Intangible Assets	Substantially all of our goodwill relates to the excess of cost over the fair value of the net assets acquired in the Columbia acquisition on November 1, 2000. Our goodwill balance was $1,485.9 million as of December 31, 2024 and 2023. The majority of our goodwill has been allocated to the Columbia Operations segment. For our annual goodwill impairment analysis performed as of May 1, 2024, we completed a quantitative ("step 1") fair value measurement of our reporting units. Fair value of our reporting units was determined based on a weighting of income and market approaches. The income approach calculated discounted cash flows using updated cash flow projections, discount rates and return on equity assumptions. The market approach applied a combination of comparable company multiples and comparable transactions and used the most recent cash flow projections. The test indicated that the fair value of each of the reporting units that are allocated goodwill exceeded their carrying values, indicating that no impairment was necessary.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2024
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	We have recognized asset retirement obligations associated with various legal obligations including costs to remove and dispose of certain construction materials located within many of our facilities (including our JV facilities), certain costs to retire pipeline, removal costs for certain underground storage tanks, removal of certain pipelines known to contain PCB contamination, closure costs for certain sites including ash ponds, solid waste management units and a landfill, as well as some other nominal asset retirement obligations. We also have an obligation associated with the decommissioning of our two hydro facilities located in Indiana. These hydro facilities have an indeterminate life, and as such, no asset retirement obligation has been recorded. During the fourth quarter of 2024, we continued to evaluate the applicability of revisions to the EPA rule for disposal of CCRs, which was announced in May 2024. As a result, we recorded an increase of $149.7 million based on initial assessments of estimated costs to comply with the EPA rule for certain sites. Additional costs will be recorded if they become probable and estimable. These costs are expected to be recoverable through existing and future depreciation rates. See Note 19, "Other Commitments and Contingencies - D. Environmental Matters," for additional information on the legacy CCR rule. Changes in our liability for asset retirement obligations for the years 2024 and 2023 are presented in the table below: (in millions) 2024 2023 Beginning Balance $ 553.0 $ 513.5 Accretion recorded as a regulatory asset/liability 25.3 20.0 Additions 189.9 23.5 Settlements (72.5) (41.6) Change in estimated cash flows 87.5 37.6 Ending Balance $ 783.2 $ 553.0 Certain non-legal costs of removal not yet incurred but have been, and continue to be, included in depreciation rates and collected in the customer rates of the rate-regulated subsidiaries are classified as "Regulatory liabilities" on the Consolidated Balance Sheets.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2024
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Assets and Liabilities We follow the accounting and reporting requirements of ASC Topic 980, which provides that regulated entities account for and report assets and liabilities consistent with the economic effect of regulatory rate-making procedures when the rates established are designed to recover the costs of providing the regulated service and it is probable that such rates will be charged and collected from customers. Certain expenses and credits subject to utility regulation or rate determination normally reflected in income or expense are deferred on the balance sheet and are recognized in the income statement as the related amounts are included in customer rates and recovered from or refunded to customers. We assess the probability of collection for all of our regulatory assets each period. Regulatory assets were comprised of the following items: At December 31, (in millions) 2024 2023 Regulatory Assets Unrecognized pension and other postretirement benefit costs (see Note 16) $ 485.3 $ 561.6 Deferred pension and other postretirement benefit costs (see Note 16) 45.3 59.7 Environmental costs (see Note 19-D.) 42.8 40.6 Regulatory effects of accounting for income taxes (see Note 1-N. and Note 15) 172.0 163.5 Under-recovered gas and fuel costs (see Note 1-J.) 82.3 12.7 Depreciation 214.9 201.9 Post-in-service carrying charges 280.8 269.9 Safety activity costs 203.7 206.6 DSM programs 17.8 25.0 Retired coal generating stations 617.0 682.0 Losses on commodity price risk programs (See Note 13) 6.5 24.4 Deferred property taxes 75.9 72.3 Renewable energy investments 81.3 60.8 WAM system filing 21.5 — Customer assistance programs 24.4 — Other 105.8 79.2 Total Regulatory Assets $ 2,477.3 $ 2,460.2 Less: Current Portion 319.9 214.3 Total Noncurrent Regulatory Assets $ 2,157.4 $ 2,245.9 Regulatory liabilities were comprised of the following items: At December 31, (in millions) 2024 2023 Regulatory Liabilities Over-recovered gas and fuel costs (see Note 1-J.) $ 21.4 $ 144.5 Cost of removal (see Note 11) 482.8 597.2 Regulatory effects of accounting for income taxes (see Note 1-N. and Note 15) 827.0 849.9 Deferred pension and other postretirement benefit costs (see Note 16) 40.4 54.0 Gains on commodity price risk programs (See Note 13) 28.7 23.3 Customer assistance programs 9.4 19.8 Off-system sales sharing 21.4 19.0 Renewable energy investments (See Note 1-S. and Note 4) 77.0 18.1 Rate refunds 16.6 16.1 Other 57.0 47.4 Total Regulatory Liabilities $ 1,581.7 $ 1,789.3 Less: Current Portion 150.5 278.6 Total Noncurrent Regulatory Liabilities $ 1,431.2 $ 1,510.7 Regulatory assets, including under-recovered gas and fuel costs and depreciation, of approximately $671.3 million and $716.4 million as of December 31, 2024 and 2023, respectively, are not earning a return on investment. These costs are recovered over a remaining life of between 15 and 75 years. Assets: Unrecognized pension and other postretirement benefit costs. Represents the deferred other comprehensive income or loss of the actuarial gains or losses and the prior service costs or credits that arise during the period but that are not immediately recognized as components of net periodic benefit costs by certain subsidiaries that will ultimately be recovered through base rates. Deferred pension and other postretirement benefit costs. Primarily relates to the difference between defined benefit plan expense recorded by certain subsidiaries due to regulatory orders and the corresponding expense that would otherwise be recorded in accordance with GAAP. This balance is driven by Columbia of Ohio deferrals. Environmental costs. Includes certain recoverable costs related to gas plant sites, disposal sites or other sites onto which material may have migrated, the recovery of which is to be addressed in future base rates, billing riders or tracking mechanisms of certain of our subsidiaries. Regulatory effects of accounting for income taxes. Represents the deferral and under collection of deferred taxes in the rate making process. Under-recovered gas and fuel costs. Represents the difference between the costs of gas and fuel, as well as energy acquired through power purchase agreements, including NIPSCO's own renewable projects, and the recovery of such costs in revenue and is used to adjust future billings for such deferrals on a basis consistent with applicable state-approved tariff provisions. Recovery of these costs is achieved through tracking mechanisms. Depreciation. Represents differences between depreciation expense incurred on a GAAP basis and that prescribed through regulatory order. The majority of this balance is driven by Columbia of Ohio's IRP and CEP deferrals. Post-in-service carrying charges. Represents deferred debt-based carrying charges incurred on certain assets placed into service but not yet included in customer rates. The majority of this balance is driven by Columbia of Ohio's IRP and CEP deferrals. Safety activity costs. Represents the difference between costs incurred by certain of our subsidiaries in eligible safety programs in compliance with PHMSA regulations in excess of those being recovered in rates. The majority of this balance is driven by Columbia of Ohio, which began recovery in March 2023 through base rates. DSM programs. Represents costs associated with Columbia Operations and NIPSCO Operations energy efficiency and conservation programs. Costs are recovered through tracking mechanisms. Retired coal generating stations. Represents the net book value of Units 7 and 8 of Bailly Generating Station that was retired during 2018 and the net book value of Units 14 and 15 of R.M. Schahfer Generating Station retired in 2021. These amounts are currently being amortized at a rate consistent with their inclusion in customer rates. The August 2023 NIPSCO electric rate case order extends the recovery of, and on, the net book value of the stations by the end of 2034 and implements a revenue credit for the retired units. The credit is based on the difference between the year-end value of Units 14 and 15 and the most recent value established in the last base rate case proceeding or credit compliance filing. Losses on commodity price risk programs . Represents the unrealized losses related to certain of our subsidiary's commodity price risk programs. These programs help to protect against the volatility of commodity prices and these amounts are collected from customers through their inclusion in customer rates. Deferred property taxes . Represents the deferral and under collection of property taxes in the rate making process for Columbia of Ohio and is driven by the IRP and CEP deferrals. Renewable energy investments. Represents the regulatory deferral of renewable energy formation and developer costs. WAM system filing . Represents the deferral of certain costs, including depreciation and amortization incurred in connection with improvements to its information technology systems through the design, development, and implementation of a new WAM program for the scheduling, dispatch, and execution of work and the management of underlying assets. Customer Assistance Programs . Represents the difference between the eligible customer assistance program costs and collections, which will be collected from customers. Liabilities: Over-recovered gas and fuel costs. Represents the difference between the cost of gas and fuel, as well as energy acquired through power purchase agreements, including NIPSCO's own renewable projects and, the recovery of such costs in revenues and is the basis to adjust future billings for such refunds on a basis consistent with applicable state-approved tariff provisions. Refunding of these revenues is achieved through tracking mechanisms. Cost of removal. Represents anticipated costs of removal for utility assets that have been collected through depreciation rates for future costs to be incurred. Regulatory effects of accounting for income taxes. Represents amounts owed to customers for deferred taxes collected at a higher rate than the current statutory rates and liabilities associated with accelerated tax deductions owed to customers. Balance includes excess deferred taxes recorded upon implementation of the TCJA in December 2017, net of amounts amortized through 2024 and federal tax credits generated by Cavalry solar facility that are passed back to customers. For discussion of the regulatory impact of the NIPSCO Minority Interest Transaction on deferred taxes, see Note 15, "Income Taxes," for additional details. Deferred pension and other postretirement benefit costs. Primarily represents cash contributions in excess of postretirement benefit expense that is deferred by certain subsidiaries. Gains on commodity price risk programs . Represents the unrealized gains related to certain of our subsidiary's commodity price risk programs. These programs help to protect against the volatility of commodity prices, and these amounts are passed back to customers through their inclusion in customer rates. Customer Assistance Programs . Represents the difference between the eligible customer assistance program costs and collections, which will be refunded to customers. Renewable energy investments. Represents the regulatory deferral of certain amounts representing the timing difference between the profit earned from the JVs and the amount included in regulated rates to recover our approved investments in consolidated JVs. The offset to the regulatory liability associated with our renewable investments is recorded in "Depreciation expense" on the Statements of Consolidated Comprehensive Income. Refer to Note 1, "Nature of Operations and Summary of Significant Accounting Policies - S. Noncontrolling Interest," Note 4, "Noncontrolling Interests," and Note 9, "Property, Plant and Equipment," for additional information. Rate Refunds . Represents supplier refunds received by the company that are owed to customers and will be remitted and amounts that are being collected in rates subject to refund. Off System Sales Sharing . Represents amounts to be passed back to the customers as a result of Off System sales that is shared between the company and the customer. Regulatory Filings Renewable generation filings In March 2024, NIPSCO filed a petition with the IURC to issue an order modifying its November 22, 2023 order to approve direct ownership of the Gibson project. Also, in March 2024, NIPSCO filed a petition with the IURC to issue an order modifying its June 29, 2021 order to approve direct ownership of the Fairbanks project. Hearings for both the Gibson project and Fairbanks project were held in June 2024 and July 2024, respectively, with orders approving direct ownership of both projects received in August 2024. NIPSCO Gas peaker filing In September 2023, NIPSCO filed a request for issuance of a CPCN for an approximately 400 MW natural gas peaking generation facility with the IURC, which was supplemented in January 2024 based on updates on availability of certain key equipment. A final order was received in October 2024 approving the request. NIPSCO Electric rate case filing On February 7, 2025, NIPSCO and certain intervening parties filed a Joint Stipulation and Settlement Agreement with the IURC. New rates proposed to be implemented in 2 steps, with implementation of Step 1 rates effective no later than September 2025 and Step 2 rates to be effective no later than March 2026. Columbia of Virginia rate case filing

Risk Management Activities

Risk Management Activities	12 Months Ended
	Dec. 31, 2024
Risk Management Activities [Abstract]
Risk Management Activities	We are exposed to certain risks related to our ongoing business operations; namely commodity price risk and interest rate risk. We recognize that the prudent and selective use of derivatives may help to limit volatility in the price of natural gas, and manage interest rate exposure. Risk management assets and liabilities on our derivatives are presented on the Consolidated Balance Sheets as shown below: December 31, 2024 December 31, 2023 (in millions) Assets Liabilities Assets Liabilities Current (1) Derivatives not designated as hedging instruments $ 9.1 $ 2.3 $ 1.1 $ 7.5 Total $ 9.1 $ 2.3 $ 1.1 $ 7.5 Noncurrent (2) Derivatives not designated as hedging instruments $ 17.9 $ 1.2 $ 22.2 $ 1.9 Total $ 17.9 $ 1.2 $ 22.2 $ 1.9 (1) Current assets and liabilities are presented in "Prepayments and other" and "Other accruals", respectively, on the Consolidated Balance Sheets. (2) Noncurrent assets and liabilities are presented in "Deferred charges and other" and "Other noncurrent liabilities and deferred credits", respectively, on the Consolidated Balance Sheets. Our derivative instruments are subject to enforceable master netting arrangements or similar agreements. No collateral was either received or posted related to our outstanding derivative positions at December 31, 2024 and 2023. If the above gross asset and liability positions were presented net of amounts owed or receivable from counterparties, we would report a net asset position of $23.5 million and $13.9 million at December 31, 2024 and 2023, respectively. Derivatives Not Designated as Hedging Instruments C ommodity price risk management. We, along with our utility customers, are exposed to variability in cash flows associated with natural gas purchases and volatility in natural gas prices. We purchase natural gas for sale and delivery to our retail, commercial and industrial customers, and for most customers the variability in the market price of gas is passed through in their rates. Some of our utility subsidiaries offer programs whereby variability in the market price of gas is assumed by the respective utility. The objective of our commodity price risk programs is to mitigate the gas cost variability, for us or on behalf of our customers, associated with natural gas purchases or sales by economically hedging the various gas cost components using a combination of futures, options, forwards or other derivative contracts. As of December 31, 2024 and 2023, we had 77.8 MMDth and 76.1 MMDth, respectively, of net energy derivative volumes outstanding related to our natural gas hedges. NIPSCO has received IURC approval to lock in a fixed price for its natural gas customers using long-term forward purchase instruments and is limited to 20% of NIPSCO’s average annual GCA purchase volume. As of December 31, 2024, the remaining terms of these instruments range from one Derivatives Designated as Hedging Instruments Interest rate risk management. As of December 31, 2024 and 2023, we had no forward-starting interest rate swaps outstanding. The overall net loss related to our multiple settled interest rate swaps is recorded to AOCI. We amortize the net loss over the life of the debt associated with these swaps as we recognize interest expense. These amounts are immaterial in 2024, 2023 and 2022 and are recorded in "Interest expense, net" on the Statements of Consolidated Income. Cash flows for derivative financial instruments are generally classified as operating activities.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value	A. Fair Value Measurements Recurring Fair Value Measurements The following tables present financial assets and liabilities measured and recorded at fair value on our Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of December 31, 2024 and December 31, 2023: Recurring Fair Value Measurements December 31, 2024 ( in millions ) Quoted Prices Significant Other Significant Balance as of December 31, 2024 Assets U.S. Treasury debt securities (1) $ 80.1 $ — $ — $ 80.1 Risk management assets — 27.0 — 27.0 Available-for-sale debt securities — 86.7 — 86.7 Total $ 80.1 $ 113.7 $ — $ 193.8 Liabilities Risk management liabilities $ — $ 3.5 $ — $ 3.5 Total $ — $ 3.5 $ — $ 3.5 (1) Treasury bills are presented in "Cash and cash equivalents" and "Restricted cash" on the Consolidated Balance Sheets. Recurring Fair Value Measurements December 31, 2023 ( in millions ) Quoted Prices Significant Other Significant Balance as of December 31, 2023 Assets Risk management assets $ — $ 23.3 $ — $ 23.3 Available-for-sale debt securities — 159.1 — 159.1 Total $ — $ 182.4 $ — $ 182.4 Liabilities Risk management liabilities $ — $ 9.4 $ — $ 9.4 Total $ — $ 9.4 $ — $ 9.4 Risk Management Assets and Liabilities. Risk management assets and liabilities include interest rate swaps, exchange-traded NYMEX futures and NYMEX options and non-exchange-based forward purchase contracts. Level 1- When utilized, exchange-traded derivative contracts are based on unadjusted quoted prices in active markets and are classified within Level 1. These financial assets and liabilities are secured with cash on deposit with the exchange; therefore, nonperformance risk has not been incorporated into these valuations. These financial assets and liabilities are deemed to be cleared and settled daily by NYMEX as the related cash collateral is posted with the exchange. As a result of this exchange rule, NYMEX derivatives are considered to have no fair value at the balance sheet date for financial reporting purposes, and are presented in Level 1 net of posted cash; however, the derivatives remain outstanding and are subject to future commodity price fluctuations until they are settled in accordance with their contractual terms. Level 2- Certain non-exchange-traded derivatives are valued using broker or over-the-counter, on-line exchanges. In such cases, these non-exchange-traded derivatives are classified within Level 2. Non-exchange-based derivative instruments include swaps, forwards, and options. In certain instances, these instruments may utilize models to measure fair value. We use a similar model to value similar instruments. Valuation models utilize various inputs that include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, other observable inputs for the asset or liability and market-corroborated inputs, (i.e., inputs derived principally from or corroborated by observable market data by correlation or other means). Where observable inputs are available for substantially the full term of the asset or liability, the instrument is categorized within Level 2. Level 3- Certain derivatives trade in less active markets with a lower availability of pricing information and models may be utilized in the valuation. When such inputs have a significant impact on the measurement of fair value, the instrument is categorized within Level 3. Credit risk is considered in the fair value calculation of derivative instruments that are not exchange-traded. Credit exposures are adjusted to reflect collateral agreements that reduce exposures. As of December 31, 2024 and 2023, there were no material transfers between fair value hierarchies. Additionally, there were no changes in the method or significant assumptions used to estimate the fair value of our financial instruments. NIPSCO and Columbia of Pennsylvania have entered into long-term forward natural gas purchase instruments to lock in a fixed price for their natural gas customers. We value these contracts using a pricing model that incorporates market-based information when available, as these instruments trade less frequently and are classified within Level 2 of the fair value hierarchy. For additional information, see Note 13, “Risk Management Activities.” Available-for-Sale Debt Securities. Available-for-sale debt securities are investments pledged as collateral for trust accounts related to our wholly-owned insurance company. We value U.S. Treasury, corporate debt and mortgage-backed securities using a matrix pricing model that incorporates market-based information. These securities trade less frequently and are classified within Level 2. Our available-for-sale debt securities impairments are recognized periodically using an allowance approach. At each reporting date, we utilize a quantitative and qualitative review process to assess the impairment of available-for-sale debt securities at the individual security level. For securities in a loss position, we evaluate our intent to sell or whether it is more-likely-than-not that we will be required to sell the security prior to the recovery of its amortized cost. If either criteria is met, the loss is recognized in earnings immediately, with the offsetting entry to the carrying value of the security. If both criteria are not met, we perform an analysis to determine whether the unrealized loss is related to credit factors. The analysis focuses on a variety of factors that include, but are not limited to, downgrade on ratings of the security, defaults in the current reporting period or projected defaults in the future, the security's yield spread over treasuries, and other relevant market data. If the unrealized loss is not related to credit factors, it is included in other comprehensive income. If the unrealized loss is related to credit factors, the loss is recognized as credit loss expense in earnings during the period, with an offsetting entry to the allowance for credit losses. The amount of the credit loss recorded to the allowance account is limited by the amount at which the security's fair value is less than its amortized cost basis. If certain amounts recorded in the allowance for credit losses are deemed uncollectible, the allowance on the uncollectible portion will be charged off, with an offsetting entry to the carrying value of the security. Subsequent improvements to the estimated credit losses of available-for-sale debt securities will be recognized immediately in earnings. As of December 31, 2024 and December 31, 2023, we recorded $0.1 million and $0.6 million, respectively, as an allowance for credit losses on available-for-sale debt securities as a result of the analysis described above. Continuous credit monitoring and portfolio credit balancing mitigates our risk of credit losses on our available-for-sale debt securities. The amortized cost, gross unrealized gains and losses, allowance for credit losses, and fair value of available-for-sale securities at December 31, 2024 and 2023 were: December 31, 2024 (in millions) Amortized Gross Gross Unrealized Losses (1) Allowance for Credit Losses Fair Value Available-for-sale debt securities Corporate/Other debt securities $ 91.9 $ 0.5 $ (5.6) $ (0.1) $ 86.7 Total $ 91.9 $ 0.5 $ (5.6) $ (0.1) $ 86.7 December 31, 2023 (in millions) Amortized Gross Gross Unrealized Losses (2) Allowance for Credit Losses Fair Value Available-for-sale debt securities U.S. Treasury debt securities $ 63.8 $ — $ (3.2) $ — $ 60.6 Corporate/Other debt securities 105.2 0.8 (6.9) (0.6) 98.5 Total $ 169.0 $ 0.8 $ (10.1) $ (0.6) $ 159.1 (1) Fair value of Corporate/Other debt securities in an unrealized loss position without an allowance for credit losses is $70.1 million at December 31, 2024. (2) Fair value of U.S. Treasury debt securities and Corporate/Other debt securities in an unrealized loss position without an allowance for credit losses is $58.7 million and $74.8 million, respectively, at December 31, 2023. Realized gains and losses on available-for-sale securities was $2.3 million for the year ended December 31, 2024 and $1.0 million for 2023. The cost of maturities sold is based upon specific identification. At December 31, 2024, approximately $10.9 million of Corporate/Other debt securities have maturities of less than a year. There are no material items in the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2024 and 2023. Additional plan investments in corporate-owned life insurance are recorded at their cash surrender value, not fair value, and therefore are not included above. These plan investments are classified as "Other investments" on the Consolidated Balance Sheets. Non-recurring Fair Value Measurements We measure the fair value of certain assets, including goodwill, on a non-recurring basis, typically when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. B. Other Fair Value Disclosures for Financial Instruments . The carrying amount of cash and cash equivalents, restricted cash, notes receivable, customer deposits and short-term borrowings is a reasonable estimate of fair value due to their liquid or short-term nature. Our long-term borrowings are recorded at historical amounts. The following method and assumptions were used to estimate the fair value of each class of financial instruments. Long-term debt . The fair value of outstanding long-term debt is estimated based on the quoted market prices for the same or similar securities. Certain premium costs associated with the early settlement of long-term debt are not taken into consideration in determining fair value. These fair value measurements are classified within Level 2 of the fair value hierarchy. For the years ended December 31, 2024 and 2023, there was no change in the method or significant assumptions used to estimate the fair value of long-term debt. The carrying amount and estimated fair values of these financial instruments were as follows: At December 31, (in millions) Carrying Amount 2024 Estimated Fair Value 2024 Carrying Amount 2023 Estimated Fair Value 2023 Long-term debt (including current portion) $ 13,355.7 $ 12,505.2 $ 11,079.3 $ 10,370.9

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Judgment and the use of estimates are required in developing the provision for income taxes and reporting of tax-related assets and liabilities. The interpretation of tax laws and associated regulations involves uncertainty as taxing authorities may interpret the laws differently. NIPSCO’s historical business activities through the closing of the NIPSCO Minority Interest Transaction in 2023 were included in the consolidated U.S. federal and certain state income tax returns of NiSource Inc. Historically, NIPSCO has been treated as a taxable division of its corporate parent, NiSource Inc., and then as a division of NIPSCO Holdings I effective April 13, 2023. In connection with the NIPSCO Minority Interest Transaction, NIPSCO Holdings I retained NIPSCO’s income tax balances and 80.1% of the excess deferred income tax regulatory balances as described below. NIPSCO Holdings I’s income tax balances are based on the difference between the financial statement amount and the tax basis of its investment in NIPSCO Holdings II. Income Tax Expense. The components of income tax expense (benefit) were as follows: Year Ended December 31, (in millions) 2024 2023 2022 Income Taxes Current Federal $ (19.3) $ — $ 0.4 State 9.4 5.3 7.3 Total Current (Benefit) Expense (9.9) 5.3 7.7 Deferred Federal Taxes before operating loss carryforwards and investment credits 105.9 49.7 87.9 Tax utilization expense of operating loss carryforwards 60.4 65.1 93.1 Investment tax credits (0.1) (2.1) — State 2.6 22.5 (23.0) Total Deferred Expense 168.8 135.2 158.0 Deferred Investment Tax Credits (0.8) (1.0) (1.1) Income Taxes from Continuing Operations $ 158.1 $ 139.5 $ 164.6 In connection with the NIPSCO Minority Interest Transaction during 2023, NiSource recognized a $63.5 million income tax benefit in additional paid in capital related to 19.9% of NIPSCO’s excess deferred income taxes attributable to Blackstone’s noncontrolling interest. This benefit does not impact NIPSCO’s regulatory books or the excess deferred taxes that will benefit customers through lower future rates in accordance with applicable regulatory orders. See Note 4, "Noncontrolling Interests," for further discussion of the NIPSCO Minority Interest Transaction. Statutory Rate Reconciliation. The following table represents a reconciliation of income tax expense at the statutory federal income tax rate to the actual income tax expense from continuing operations: Year Ended December 31, (in millions) 2024 2023 2022 Book income before income taxes $ 1,002.8 $ 813.9 $ 956.4 Tax expense at statutory federal income tax rate 210.6 21.0 % 170.8 21.0 % 200.8 21.0 % Increases (reductions) in taxes resulting from: State income taxes, net of federal income tax benefit 11.7 1.2 13.7 1.7 4.5 0.5 Amortization of regulatory liabilities (11.1) (1.1) (38.2) (4.7) (38.5) (4.0) Employee stock ownership plan dividends and other compensation (1.3) (0.1) (1.3) (0.2) (1.2) (0.1) Federal tax credits (23.3) (2.3) (4.9) (0.6) (2.3) (0.2) Tax effect of non-controlling Interest (27.3) (2.7) — — — — Other adjustments (1.2) (0.2) (0.6) (0.1) 1.3 — Income Taxes $ 158.1 15.8 % $ 139.5 17.1 % $ 164.6 17.2 % The increase in tax expense of $18.6 million in 2024 versus 2023 was primarily due to higher pre-tax income, partially offset by the tax effect of non-controlling interest, and higher federal tax credits generated by the Cavalry solar and storage facility that are offset in a regulatory liability to pass back to customers in future periods. The decrease in the Amortization of Regulatory Liabilities in 2024 versus 2023 was primarily due to the regulatory liability established for the Cavalry tax credits generated in 2024, net of TCJA excess deferred amortization which decreased approximately $7.9 million from the prior year. The difference in tax expense of $25.1 million in 2023 versus 2022 was primarily due to lower pre-tax income. Net Deferred Income Tax Liability Components. Deferred income taxes result from temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. The principal components of our net deferred tax liabilities were as follows: At December 31, (in millions) 2024 2023 Deferred tax liabilities Accelerated depreciation and other property differences $ 1,419.4 $ 1,384.8 Partnership basis differences 1,328.6 1,241.9 Other regulatory assets 210.1 212.1 Total Deferred Tax Liabilities 2,958.1 2,838.8 Deferred tax assets Other regulatory liabilities and deferred investment tax credits (including TCJA) 170.4 182.2 Pension and other postretirement/postemployment benefits 58.8 58.6 Loss and credit carryforwards 369.4 422.9 Environmental liabilities 12.2 10.1 Other accrued liabilities 43.4 40.3 Other, net 28.7 50.7 Total Deferred Tax Assets 682.9 764.8 Valuation Allowance (6.4) (6.4) Net Deferred Tax Assets 676.5 758.4 Net Deferred Tax Liabilities $ 2,281.6 $ 2,080.4 In connection with the NIPSCO Minority Interest Transaction, NIPSCO’s deferred taxes were removed from its GAAP books and were reconstituted as deferred taxes on the outside basis difference of NiSource’s investment in NIPSCO Holdings II. These deferred taxes are reflected as partnership basis differences above. NiSource has the following deductible loss and credit carryforwards: At December 31, 2024 (in millions) Deductible Amount Deferred Tax Asset Valuation Allowance Expiration Period Federal losses $ 1,369.1 $ 287.5 $ — 2037 Federal investment tax credits — 2.2 — 2043 Federal production tax credits — 1.0 — 2040-2043 Federal other credit — 17.3 — 2029-2043 State losses 2,024.4 81.9 (6.4) 2031-2037 Total $ 389.9 $ (6.4) We believe it is not more likely than not that a portion of the benefit from certain state net operating loss carryforwards will be realized. We have recorded a valuation allowance of $6.4 million on the deferred tax assets related to sale of Massachusetts Business assets reflected in the state net operating loss carryforward presented above. Unrecognized Tax Benefits. A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows: At December 31, 2024 (in millions) 2024 2023 2022 Opening Balance $ 21.7 $ 21.7 $ 21.7 Gross decreases - tax positions in prior period — — — Gross increases - current period tax positions — — — Ending Balance $ 21.7 $ 21.7 $ 21.7 Offset for net operating loss carryforwards (21.7) (21.7) (21.7) Balance, Less Net Operating Loss Carryforwards $ — $ — $ — We are subject to income taxation in the United States and various state jurisdictions, primarily Indiana, Pennsylvania, Kentucky, Massachusetts, Maryland and Virginia. We participate in the IRS CAP, which provides the opportunity to resolve tax matters with the IRS before filing each year's consolidated federal income tax return. As of December 31, 2024, tax years through 2021 have been audited and are closed to further assessment. The Company has transitioned to the Bridge Phase of the IRS CAP for the year ended December 31, 2022 and participated in the Bridge Plus pilot program in 2022 and 2023. NiSource received a full acceptance letter from the IRS for its 2022 return, but has not yet received a final acceptance letter from the IRS for its 2023 return. However, no adjustments are expected, and the year is effectively closed to further assessment. The statute of limitations in each of the state jurisdictions in which we operate remains open between 3-4 years from the date the state income tax returns are filed. As of December 31, 2024, there were no state income tax audits in progress that would have a material impact on the consolidated financial statements. NiSource is obligated to report adjustments resulting from IRS audits or settlements to state taxing authorities. In addition, if NiSource utilizes net operating losses or tax credits generated in years for which the statute of limitations has expired, such amounts are generally subject to examination. On April 14, 2023, the IRS issued Revenue Procedure 2023-15 which provides a safe harbor method of accounting that taxpayers may use to determine whether expenses to repair, maintain, replace, or improve linear property and non-linear natural gas transmission and distribution property must be capitalized as improvements or are allowable as deductions. On June 3, 2024, the IRS extended the favorable rules to a Year 2 adoption period. The Company is planning to elect this change in tax accounting method with its 2024 consolidated tax return filing in the upcoming year and continues to analyze and quantify the provisions of the safe harbor method of accounting.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2024
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension and Other Postretirement Benefits	We provide defined contribution plans and noncontributory defined benefit retirement plans that cover certain of our employees. Benefits under the defined benefit retirement plans reflect the employees’ compensation, years of service and age at retirement. Additionally, we provide health care and life insurance benefits for certain retired employees. The majority of employees may become eligible for these benefits if they reach retirement age while working for us. The expected cost of such benefits is accrued during the employees’ years of service. Current rates of rate-regulated companies include postretirement benefit costs, including amortization of the regulatory assets that arose prior to inclusion of these costs in rates. For most plans, cash contributions are remitted to grantor trusts. Our Pension and Other Postretirement Benefit Plans’ Asset Management . The Board has delegated oversight of the pension and other postretirement benefit plans’ assets to the NiSource Benefits Committee (the "Committee"). The Committee has adopted investment policy statements for the pension and other postretirement benefit plans’ assets. For the pension plans, we employ a liability-driven investing strategy. A total return approach is utilized for the other postretirement benefit plans’ assets. A mix of diversified investments are used to maximize the long-term return of plan assets and hedge the liabilities at a prudent level of risk. The investment portfolio includes U.S. and non-U.S. equities, real estate, long-term and intermediate-term fixed income and alternative investments. Risk tolerance is established through careful consideration of plan liabilities, funded status, and asset class volatility. Investment risk is measured and monitored on an ongoing basis through quarterly investment portfolio reviews, annual liability measurements, and periodic asset/liability studies. In determining the expected long-term rate of return on plan assets, historical markets are studied, relationships between equities and fixed income are analyzed and current market factors, such as inflation and interest rates are evaluated with consideration of diversification and rebalancing. Our expected long-term rate of return on assets is based on assumptions regarding target asset allocations and corresponding long-term capital market assumptions for each asset class. The pension plans’ investment policy calls for a gradual reduction in the allocation of return-seeking assets (equities, real estate and private equity) and a corresponding increase in the allocation of liability-hedging assets (fixed income) as the funded status of the plans’ increase. As of December 31, 2024 and December 31, 2023, the acceptable minimum and maximum ranges established by the policy for the pension and other postretirement benefit plans are as follows: December 31, 2024 Defined Benefit Pension Plan Postretirement Benefit Plan Asset Category Minimum Maximum Minimum Maximum Domestic Equities 10% 30% 0% 55% International Equities 5% 15% 0% 25% Fixed Income 65% 75% 20% 100% Real Estate 0% 0% 0% 0% Private Equity 0% 3% 0% 0% Short-Term Investments 0% 10% 0% 10% December 31, 2023 Defined Benefit Pension Plan Postretirement Benefit Plan Asset Category Minimum Maximum Minimum Maximum Domestic Equities 10% 30% 0% 55% International Equities 5% 15% 0% 25% Fixed Income 65% 75% 20% 100% Real Estate 0% 0% 0% 0% Private Equity 0% 3% 0% 0% Short-Term Investments 0% 10% 0% 10% The actual Pension Plan and Postretirement Plan Asset Mix at December 31, 2024 and December 31, 2023 are as follows: Defined Benefit Pension Assets (1) December 31, Postretirement December 31, Asset Class (in millions) Asset Value % of Total Assets Asset Value % of Total Assets Domestic Equities $ 258.9 19.4 % $ 99.6 40.9 % International Equities 122.5 9.2 % 40.7 16.7 % Fixed Income 891.2 66.7 % 96.5 39.6 % Real Estate 4.0 0.3 % — — Cash/Other 59.8 4.4 % 6.7 2.8 % Total $ 1,336.4 100.0 % $ 243.5 100.0 % (1) Total includes accrued dividends and pending trades with brokers. Defined Benefit Pension Assets (1) December 31, Postretirement Benefit Plan Assets (1) December 31, Asset Class (in millions) Asset Value % of Total Assets Asset Value % of Total Assets Domestic Equities $ 261.7 18.3 % $ 93.7 39.6 % International Equities 141.9 9.9 % 40.7 17.2 % Fixed Income 939.9 65.9 % 97.0 41.0 % Real Estate 4.0 0.3 % — — Cash/Other 79.3 5.6 % 5.1 2.2 % Total $ 1,426.8 100.0 % $ 236.5 100.0 % (1) Total includes accrued dividends and pending trades with brokers. The categorization of investments into the asset classes in the tables above are based on definitions established by the Committee. Fair Value Measurements. The following table sets forth, by level within the fair value hierarchy, the pension and other postretirement benefits investment assets at fair value as of December 31, 2024 and 2023. Assets are classified in their entirety based on the observability of inputs used in determining the fair value measurement. There were no material investment assets in the pension and other postretirement benefits trusts classified within Level 3 for the years ended December 31, 2024 and 2023. We use the following valuation techniques to determine fair value. For the year ended December 31, 2024, there were no significant changes to valuation techniques to determine the fair value of our pension and other postretirement benefits' assets. Level 1 Measurements Most common and preferred stocks are traded in active markets on national and international securities exchanges and are valued at closing prices on the last business day of each period presented. Cash is stated at cost, which approximates fair value, with the exception of cash held in foreign currencies which fluctuates with changes in the exchange rates. Short-term bills and notes are priced based on quoted market values. Level 2 Measurements Most U.S. Government Agency obligations, mortgage/asset-backed securities, and corporate fixed income securities are generally valued by benchmarking model-derived prices to quoted market prices and trade data for identical or comparable securities. To the extent that quoted prices are not available, fair value is determined based on a valuation model that includes inputs such as interest rate yield curves and credit spreads. Securities traded in markets that are not considered active are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Other fixed income includes futures and options which are priced on bid valuation or settlement pricing. Level 3 Measurements Investments with unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities are classified as level 3 investments. Not Classified Commingled funds, private equity limited partnerships and real estate partnerships are not classified within the fair value hierarchy. Instead, these assets are measured at estimated fair value using the net asset value per share of the investments. Commingled funds' underlying assets are principally marketable equity and fixed income securities. Units held in commingled funds are valued at the unit value as reported by the investment managers. Private equity funds invest capital in non-public companies and real estate funds invest in commercial and distressed real estate directly or through related debt instruments. The fair value of these investments is determined by reference to the funds’ underlying assets. Fair Value Measurements at December 31, 2024: (in millions) December 31, Quoted Prices in Active Markets for Significant Other Significant Pension plan assets: Cash $ 1.2 $ 1.1 $ 0.1 $ — Fixed income securities Government 186.8 — 186.8 — Corporate 486.6 — 486.6 — Mortgages/ Asset Backed Securities 3.6 — 3.6 — Mutual Funds U.S. multi-strategy 56.1 56.1 — — International equities 57.2 57.2 — — Private equity limited partnerships (1) U.S. multi-strategy (2) 3.1 — — — International multi-strategy (3) 0.8 — — — Distressed opportunities 0.1 — — — Real estate (1) 4.0 — — — Commingled funds (1) Short-term money markets 45.9 — — — U.S. equities 202.8 — — — International equities 65.3 — — — Fixed income 214.1 — — — Pension plan assets subtotal $ 1,327.6 $ 114.4 $ 677.1 $ — Other postretirement benefit plan assets: Mutual funds U.S. multi-strategy 87.4 87.4 — — International equities 16.5 16.5 — — Fixed income 96.5 96.5 — — Commingled funds (1) Short-term money markets 6.7 — — — U.S. equities 12.2 — — — International equities 24.2 — — — Other postretirement benefit plan assets subtotal $ 243.5 $ 200.4 $ — $ — Due to brokers, net (4) (0.1) — (0.1) — Accrued income/dividends 8.9 8.9 — Total pension and other postretirement benefit plan assets $ 1,579.9 $ 323.7 $ 677.0 $ — (1)) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. (2) This class includes limited partnerships that invest in a diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily inside the United States. (3) This class includes limited partnerships that invest a in diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily outside the United States. (4) This class represents pending trades with brokers. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2024: (in millions) Fair Value Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 52.6 Daily 1 day U.S. equities 215.0 Daily 1 day - 5 days International equities 89.5 Monthly 10 days-30 days Fixed income 214.1 Daily 3 days Private Equity and Real Estate Limited Partnerships (1) 8.0 N/A N/A Total $ 579.2 (1) Private equity and real estate limited partnerships typically call capital over a 3-5 year period and pay out distributions as the underlying investments are liquidated. The typical expected life of these limited partnerships is 0-15 years, and these investments typically cannot be redeemed prior to liquidation. Fair Value Measurements at December 31, 2023: (in millions) December 31, Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Significant Pension plan assets: Cash $ 2.2 $ 2.0 $ 0.2 $ — Equity securities International equities 1.1 1.1 — — Fixed income securities Government 213.1 — 213.1 — Corporate 482.2 — 482.2 — Mortgages/Asset backed securities 2.4 — 2.4 — Mutual Funds U.S. multi-strategy 113.1 113.1 — — International equities 38.5 38.5 — — Private equity limited partnerships (1) U.S. multi-strategy (2) 4.8 — — — International multi-strategy (3) 1.2 — — — Distressed opportunities 0.1 — — — Real estate (1) 4.0 — — — Commingled funds (1) Short-term money markets 65.3 — — — U.S. equities 148.5 — — — International equities 102.3 — — — Fixed income 242.2 — — — Pension plan assets subtotal $ 1,421.0 $ 154.7 $ 697.9 $ — Other postretirement benefit plan assets: Mutual funds U.S. multi-strategy 82.4 82.4 — — International equities 18.0 18.0 — — Fixed income 97.0 97.0 — — Commingled funds (1) Short-term money markets 5.2 — — — U.S. equities 11.4 — — — International equities 22.8 — — — Other postretirement benefit plan assets subtotal $ 236.8 $ 197.4 $ — $ — Due to brokers, net (4) (2.7) — (2.7) — Accrued income/dividends 8.5 8.5 — — Total pension and other postretirement benefit plan assets $ 1,663.6 $ 360.6 $ 695.2 $ — (1) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. (2) This class includes limited partnerships/fund of funds that invest in a diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily inside the United States. (3) This class includes limited partnerships/fund of funds that invest in diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily outside the United States. (4) This class represents pending trades with brokers. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2023: (in millions) Fair Value Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 70.5 Daily 1 day U.S. equities 159.9 Daily 1 day -5 days International equities 125.1 Monthly 10 days - 30 days Fixed income 242.2 Daily 3 days Private Equity and Real Estate Limited Partnerships (1) 10.1 N/A N/A Total $ 607.8 (1) Private equity and real estate limited partnerships typically call capital over a 3-5 year period and pay out distributions as the underlying investments are liquidated. The typical expected life of these limited partnerships is 0-15 years, and these investments typically cannot be redeemed prior to liquidation. Our Pension and Other Postretirement Benefit Plans’ Funded Status and Related Disclosure . The following table provides a reconciliation of the plans’ funded status and amounts reflected in our Consolidated Balance Sheets at December 31 based on a December 31 measurement date: Pension Benefits Other Postretirement Benefits (in millions) 2024 2023 2024 2023 Change in projected benefit obligation (1) Benefit obligation at beginning of year $ 1,401.8 $ 1,427.4 $ 468.8 $ 449.0 Service cost 21.9 20.5 5.0 5.1 Interest cost 64.9 68.4 22.0 21.8 Plan participants’ contributions — — 3.6 4.2 Plan amendments — — — 3.4 Actuarial loss (gain) (2) (64.8) 27.4 (22.5) 29.1 Benefits paid (136.4) (141.9) (40.7) (44.3) Estimated benefits paid by incurred subsidy — — 0.1 0.5 Projected benefit obligation at end of year $ 1,287.4 $ 1,401.8 $ 436.3 $ 468.8 Change in plan assets Fair value of plan assets at beginning of year $ 1,426.8 $ 1,422.8 $ 236.5 $ 224.9 Actual return on plan assets 43.7 142.8 20.0 28.2 Employer contributions 2.4 3.1 23.6 23.4 Plan participants’ contributions — — 3.8 4.3 Benefits paid (136.4) (141.9) (40.7) (44.3) Fair value of plan assets at end of year $ 1,336.5 $ 1,426.8 $ 243.2 $ 236.5 Funded Status at end of year $ 49.1 $ 25.0 $ (193.1) $ (232.3) Amounts recognized in the statement of financial position consist of: Noncurrent assets 66.5 44.1 — — Current liabilities (2.3) (2.2) (1.0) (1.0) Noncurrent liabilities (15.1) (16.9) (192.1) (231.3) Net amount recognized at end of year (3) $ 49.1 $ 25.0 $ (193.1) $ (232.3) Amounts recognized in accumulated other comprehensive income or regulatory asset/liability (4) Unrecognized prior service credit $ 0.3 $ 0.3 $ 3.8 $ 2.1 Unrecognized actuarial loss 451.4 500.4 47.0 76.6 Net amount recognized at end of year $ 451.7 $ 500.7 $ 50.8 $ 78.7 (1) The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in accumulated postretirement benefit obligation. (2) The pension actuarial gain was primarily driven by the increase in discount rates interest rate movements. The postretirement benefit actuarial loss (gain) was also primarily driven by a increase in discount rates and claims experience changes in trend rates. (3) We recognize our Consolidated Balance Sheets underfunded and overfunded status of our various defined benefit postretirement plans, measured as the difference between the fair value of the plan assets and the benefit obligation. (4) We determined that for certain rate-regulated subsidiaries the future recovery of pension and other postretirement benefits costs is probable. These rate-regulated subsidiaries recorded regulatory assets and liabilities of $485.3 million and zero, respectively, as of December 31, 2024, and $561.6 million and zero, respectively, as of December 31, 2023 that would otherwise have been recorded to accumulated other comprehensive loss. Our accumulated benefit obligation for our pension plans was $1,278.4 million and $1,390.9 million as of December 31, 2024 and 2023, respectively. The accumulated benefit obligation at each date is the actuarial present value of benefits attributed by the pension benefit formula to employee service rendered prior to that date and based on current and past compensation levels. The accumulated benefit obligation differs from the projected benefit obligation disclosed in the table above in that it includes no assumptions about future compensation levels. We are required to reflect the funded status of our pension and postretirement benefit plans on the Consolidated Balance Sheet. The funded status of the plans is measured as the difference between the plan assets' fair value and the projected benefit obligation. We present the noncurrent aggregate of all underfunded plans within "Accrued liability for postretirement and postemployment benefits." The portion of the amount by which the actuarial present value of benefits included in the projected benefit obligation exceeds the fair value of plan assets, payable in the next 12 months, is reflected in "Accrued compensation and other benefits." We present the aggregate of all overfunded plans within "Deferred charges and other." For our pension plans as of December 31, 2024 and 2023, only our nonqualified plans were underfunded. These plans have no assets as they are not funded until benefits are paid. The following table sets forth the year end accumulated benefit obligation and projected benefit obligation for pension plans with a projected benefit obligation in excess of plan assets: December 31, 2024 2023 Accumulated Benefit Obligation $ 17.4 $ 19.1 Funded Status Projected Benefit Obligation $ 17.4 $ 19.1 Funded Status of Underfunded Pension Plans at End of Year $ (17.4) $ (19.1) The following table sets forth the year end accumulated benefit obligation, projected benefit obligation and fair value of plan assets for pension plans with plan assets in excess of the projected benefit obligation: December 31, 2024 2023 Accumulated Benefit Obligation $ 1,261.0 $ 1,371.8 Funded Status Fair Value of Plan Assets $ 1,336.4 $ 1,426.8 Projected Benefit Obligation 1,269.9 1,382.7 Funded Status of Overfunded Pension Plans at End of Year $ 66.5 $ 44.1 Our pension plans were overfunded, in aggregate, by $49.1 million at December 31, 2024 compared to being overfunded by $25.0 million at December 31, 2023. The improvement in the funded status was primarily due to an increase in discount rates partially offset by actual return on assets being less than expected return on assets. We contributed $2.4 million and $3.1 million to our pension plans in 2024 and 2023, respectively. Our other postretirement benefit plans were underfunded, in aggregate by $193.1 million and $232.3 million at December 31, 2024 and 2023, respectively. The change in funded status was primarily due to increased discount rates and actual return on plan assets exceeding expected return. We contributed $23.6 million and $23.4 million to our other postretirement benefit plans in 2024 and 2023, respectively. In 2024 and 2023, our NiSource Pension Restoration and Columbia Energy Group pension plans paid lump sum payouts in excess of the respective plan's service cost plus interest cost, thereby meeting the requirement for settlement accounting. We recorded settlement charges of $7.2 million and $9.2 million in 2024 and 2023, respectively. In 2024 and 2023, no remeasurement occurred related to lump sum payouts. The following table provides the key assumptions that were used to calculate the pension and other postretirement benefits obligations for our various plans as of December 31: Pension Benefits Other Postretirement Benefits 2024 2023 2024 2023 Weighted-average assumptions to Determine Benefit Obligation Discount Rate 5.58 % 4.95 % 5.66 % 4.98 % Rate of Compensation Increases 4.00 % 4.00 % N/A N/A Interest Crediting Rates 4.00 % 4.00 % N/A N/A Health Care Trend Rates Trend for Next Year N/A N/A 9.77 % 8.84 % Ultimate Trend N/A N/A 4.75 % 4.75 % Year Ultimate Trend Reached N/A N/A 2033 2032 We expect to make contributions of approximately $2.3 million to our pension plans and approximately $21.3 million to our postretirement medical and life plans in 2025. The following table provides benefits expected to be paid in each of the next five fiscal years, and in the aggregate for the five fiscal years thereafter. The expected benefits are estimated based on the same assumptions used to measure our benefit obligation at the end of the year and include benefits attributable to the estimated future service of employees: (in millions) Pension Benefits Other Year(s) 2025 $ 142.6 $ 36.6 2026 136.6 36.1 2027 130.9 36.1 2028 125.8 35.8 2029 119.4 35.6 2030-2034 528.6 171.7 The following table provides the components of the plans’ actuarially determined net periodic benefits cost for each of the three years ended December 31, 2024, 2023 and 2022: Pension Benefits Other Postretirement (in millions) 2024 2023 2022 2024 2023 2022 Components of Net Periodic Benefit (Income) Cost (1) Service cost $ 21.9 $ 20.5 $ 27.8 $ 5.0 $ 5.1 $ 6.5 Interest cost 64.9 68.4 40.5 22.0 21.8 12.0 Expected return on assets (95.3) (94.5) (90.8) (16.1) (15.1) (16.2) Amortization of prior service cost (credit) 0.1 0.1 0.1 (1.8) (2.1) (2.2) Recognized actuarial loss 28.6 33.7 20.3 3.2 3.3 2.6 Settlement loss 7.2 9.2 12.4 — — — Total Net Periodic Benefits Cost $ 27.4 $ 37.4 $ 10.3 $ 12.3 $ 13.0 $ 2.7 (1) Service cost is presented in "Operation and maintenance" on the Statements of Consolidated Income. Non-service cost components are presented within "Other, net." The following table provides the key assumptions that were used to calculate the net periodic benefits cost for our various plans: Pension Benefits Other Postretirement 2024 2023 2022 2024 2023 2022 Weighted-average Assumptions to Determine Net Periodic Benefit Cost Discount rate - service cost 5.06 % 5.25 % 3.08 % 5.14 % 5.30 % 3.21 % Discount rate - interest cost 4.88 % 5.06 % 2.11 % 4.89 % 5.07 % 2.24 % Expected Long-Term Rate of Return on Plan Assets 7.02 % 7.00 % 4.80 % 7.06 % 6.96 % 5.72 % Rate of Compensation Increases 4.00 % 4.00 % 4.00 % N/A N/A N/A Interest Crediting Rates 4.00 % 4.00 % 4.00 % N/A N/A N/A We assumed a 7.02% and 7.06% rate of return on pension and other postretirement plan assets, respectively, for our calculation of 2024 pension benefits and other postretirement benefits costs. These rates were primarily based on asset mix and historical rates of return and were adjusted in 2024 due to changes in asset allocation and projected market returns. The following table provides other changes in plan assets and projected benefit obligations recognized in other comprehensive income or regulatory asset or liability: Pension Benefits Other Postretirement (in millions) 2024 2023 2024 2023 Other Changes in Plan Assets and Projected Benefit Obligations Net prior service cost $ — $ — $ — $ 3.3 Net actuarial (gain) loss (13.1) (20.9) (26.4) 16.0 Settlements/curtailments (7.2) (9.2) — — Less: amortization of prior service cost (0.1) (0.1) 1.8 2.1 Less: amortization of net actuarial loss (28.6) (33.7) (3.2) (3.3) Total Recognized in Other Comprehensive Income or Regulatory $ (49.0) $ (63.9) $ (27.8) $ 18.1 Amount Recognized in Net Periodic Benefits Cost and Other $ (21.6) $ (26.5) $ (15.5) $ 31.1

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2024
Share-Based Payment Arrangement, Noncash Expense [Abstract]
Share-Based Compensation	Prior to May 19, 2020, we issued share-based compensation to employees and non-employee directors under the NiSource Inc. 2010 Omnibus Plan ("2010 Omnibus Plan"), which was most recently approved by stockholders at the Annual Meeting of Stockholders held on May 12, 2015. The 2010 Omnibus Plan provided for awards to employees and non-employee directors of incentive and nonqualified stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance units, cash-based awards and other stock-based awards and superseded the Director Stock Incentive Plan (“Director Plan”) with respect to grants made after the effective date of the 2010 Omnibus Plan. The stockholders approved and adopted the NiSource Inc. 2020 Omnibus Incentive Plan ("2020 Omnibus Plan") at the Annual Meeting of Stockholders held on May 19, 2020. The 2020 Omnibus Plan provides for awards to employees and non-employee directors of incentive and nonqualified stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance units, cash-based awards and other stock-based awards and supersedes the 2010 Omnibus Plan with respect to grants made after the effective date of the 2020 Omnibus Plan. The 2020 Omnibus Plan provides that the number of shares of common stock of NiSource available for awards is 10,000,000 plus the number of shares subject to outstanding awards that expire or terminate for any reason that were granted under the 2020 Omnibus Plan, the 2010 Omnibus Plan or any other equity plan under which awards were outstanding as of May 19, 2020. At December 31, 2024, there were 7,216,823 shares available for future awards under the 2020 Omnibus Plan. We recognized stock-based employee compensation expense of $32.1 million, $23.9 million and $19.0 million, during 2024, 2023 and 2022, respectively, as well as related tax benefits of $7.0 million, $7.7 million and $3.6 million, respectively. We recognized related excess tax benefits from the distribution of vested share-based employee compensation of $2.0 million, $2.9 million, and $0.4 million in 2024, 2023 and 2022, respectively. As of December 31, 2024, the total remaining unrecognized compensation cost related to non-vested awards amounted to $46.7 million, which will be amortized over the weighted-average remaining requisite service period of 1.8 years. Restricted Stock Units and Restricted Stock . We granted 655,713, 500,968, and 477,292 restricted stock units and shares of restricted stock to employees, subject to service conditions in 2024, 2023, and 2022, respectively. The total grant date fair value of the restricted stock units and shares of restricted stock during 2024, 2023, and 2022, respectively, was $17.1 million, $13.7 million, and $12.5 million. The grant date fair value for the 2024 and 2023 awards is based on the average market price of our common stock at the date of each grant. For the year ended 2022, the grant date fair value is based on the average market price of our common stock at the date of each grant less the present value of any dividends not received during the vesting period. The awards are expensed over the vesting period which is generally three years. As of December 31, 2024, 592,490, 393,509, and 270,325 non-vested restricted stock units and shares of restricted stock granted in 2024, 2023, and 2022, respectively, were outstanding. Our non-vested restricted stock units have a non-forfeitable right to dividend equivalents, with immaterial amounts paid in the periods ending December 31, 2024 and 2023. See Note 5, "Earnings Per Share," for further discussion. In general, if an employee terminates employment before the service conditions lapse under the 2022, 2023 or 2024 awards due to (1) retirement or disability (as defined in the 2020 Omnibus Plan), or (2) death, the service conditions will lapse on the date of such termination with respect to a pro rata portion of the restricted stock units and shares of restricted stock based upon the percentage of the service period satisfied between the grant date and the date of the termination of employment. In the event of a change in control (as defined in the 2020 Omnibus Plan), all unvested shares of restricted stock and restricted stock units awarded will immediately vest upon termination of employment occurring in connection with a change in control. Termination due to any other reason, in general, will result in all unvested shares of restricted stock and restricted stock units awarded being forfeited effective on the employee’s date of termination. A summary of our restricted stock unit award transactions for the year ended December 31, 2024 is as follows: (shares) Restricted Stock Weighted Average Non-vested at December 31, 2023 1,066,916 25.71 Granted 655,713 26.10 Forfeited (167,057) 26.19 Vested (227,452) 22.90 Non-vested at December 31, 2024 1,328,120 26.49 Employee Performance Shares . We granted 896,363 performance shares subject to service, performance and/or market-based vesting conditions in 2024. The performance conditions for these shares are based on the achievement of one non-GAAP financial measure, achievement of relative total shareholder return, and other operational metrics, which make up 55%, 25%, and 20% of the issued awards respectively. The non-GAAP financial measure is cumulative adjusted earnings per share, which we define as diluted earnings per share adjusted for certain items. Relative total shareholder return, a market-based vesting condition, which we define as the annualized growth in dividends and share price of a share of our common stock (calculated using a 20 trading day average of our closing price over the performance period, approximately) compared to the total shareholder return of a predetermined peer group of companies. A Monte Carlo analysis was used to value the portion of these awards dependent on the market-based vesting condition. The grant date fair value of the non-GAAP financial measure shares is based on the closing stock price of our common stock at the date of each grant, which will be expensed over the requisite service period of three years. The conditions for the remaining performance-based awards are based on operational goals of Annual Operational Index Scorecard (10%), Employee Engagement Index Score (5%), and Environmental Greenhouse Gas Reduction (5%). In 2023, we granted 649,088 performance shares subject to service, performance and/or market-based vesting conditions. The performance conditions for these shares are based on the achievement of one non-GAAP financial measure, achievement of relative total shareholder return, and other operational metrics, which make up 50%, 25%, and 25% of the issued awards respectively. The operational metrics consist of goals of economic inclusion (5%), OPEX ("Operating Expenses") Index (10%), Employee Engagement Index Score (5%), and Environmental GHG Reduction (5%). The OPEX Index is further defined by goals related to risk mitigation and modernization of our infrastructure. In 2022, we granted 566,086 performance shares subject to service, performance and/or market-based vesting conditions. The performance conditions for these shares are based on the achievement of one non-GAAP financial measure, and/or achievement of relative total shareholder return, outlined above. The number of shares that are eligible to vest based on these performance conditions are adjusted based on performance of the magnifier framework for 2022 awards. The operational magnifier framework for 2022 performance shares consists of three areas of focus, including safety, environment, and workforce, representing 20%, 10% and 10%, respectively. The following table presents details of the performance awards described above. Award Year Service Conditions Lapse date Performance Period Award Conditions Shares outstanding at 12/31/2024 (shares) Grant Date Fair Value (in millions) 2024 2/26/2027 01/01/2024- 12/31/2026 Non-GAAP Financial and Operational Measures 619,673 $ 17.4 Relative Total Shareholder Return 206,524 $ 6.9 2023 2/28/2026 01/01/2023- 12/31/2025 Non-GAAP Financial and Operational Measures 430,670 $ 13.3 Relative Total Shareholder Return 143,540 $ 5.4 2022 2/28/2025 01/01/2022- 12/31/2024 Non-GAAP Financial Measure 195,460 $ 7.4 Relative Total Shareholder Return 195,460 $ 10.6 A summary of our performance award transactions for the year ended December 31, 2024 is as follows: (shares) Performance Weighted Average Non-vested at December 31, 2023 1,558,509 28.01 Granted 896,363 27.05 Forfeited (189,080) 31.75 Vested (546,569) 21.95 Non-vested at December 31, 2024 1,719,223 24.96 Non-employee Director Awards . As of May 19, 2020, awards to non-employee directors may be made only under the 2020 Omnibus Plan. Currently, restricted stock units are granted annually to non-employee directors, subject to a non-employee director’s election to defer receipt of such restricted stock unit award. The non-employee director’s annual award of restricted stock units vest on the first anniversary of the grant date subject to special pro-rata vesting rules in the event of retirement or disability (as defined in the award agreement), or death. The vested restricted stock units are payable as soon as practicable following vesting except as otherwise provided pursuant to the non-employee director’s deferral election. Certain restricted stock units remain outstanding from the 2010 Omnibus Plan and the Director Plan. All such awards are fully vested and shall be distributed to the directors upon their separation from the Board. As of December 31, 2024, 292,566 restricted stock units are outstanding to non-employee directors under either the 2020 Omnibus Plan, the 2010 Omnibus Plan or the Director Plan. Of this amount, 68,436 restricted stock units are unvested and expected to vest. 401(k) Match, Profit Sharing and Company Contribution. Eligible salaried employees hired after January 1, 2010 and hourly and union employees hired after January 1, 2013 receive a non-elective company contribution of 4.5% of eligible pay payable in cash or shares of NiSource common stock. We also have a voluntary 401(k) savings plan covering eligible union and nonunion employees that allows for periodic discretionary matches as a percentage of each participant’s contributions payable in cash or shares. Further, we have a retirement savings plan that provides for discretionary profit sharing contributions to eligible employees. For the years ended December 31, 2024, 2023 and 2022, we recognized 401(k) match, profit sharing and non-elective contribution expense of $56.9 million, $50.7 million and $39.1 million, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2024
Leases [Abstract]
Lessee, Operating Leases	Lease Descriptions. We are the lessee for substantially all of our leasing activity, which includes operating and finance leases for corporate and field offices, railcars, land, and fleet vehicles. Our corporate and field office leases and certain land leases have remaining terms between 1 and 39 years with options to renew the leases for up to 35 years. We lease railcars to transport coal to and from our electric generation facilities in Indiana. Our railcars are specifically identified in the lease agreements which have remaining lease terms between 1 and 3 years with options to renew for 1 year. Our fleet vehicles include trucks, trailers and equipment that have been customized specifically for use in the utility industry. We lease fleet vehicles for 1 year terms, after which we have the option to extend on a month-to-month basis or terminate with written notice. We elected the short-term lease practical expedient, allowing us to not recognize ROU assets or lease liabilities for all leases with a term of 12 months or less. ROU assets and liabilities on our Consolidated Balance Sheets do not include obligations for possible fleet vehicle lease renewals beyond the initial lease term. While we have the ability to renew these leases beyond the initial term, we are not reasonably certain to do so. We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants. Lease contracts containing renewal and termination options are mostly exercisable at our sole discretion. Certain of our real estate and railcar leases include renewal periods in the measurement of the lease obligation if we have deemed the renewals reasonably certain to be exercised. With respect to service contracts involving the use of assets, if we have the right to direct the use of the asset and obtain substantially all economic benefits from the use of an asset, we account for the service contract as a lease. Unless specifically provided to us by the lessor, we utilize NiSource's collateralized incremental borrowing rate commensurate to the lease term as the discount rate for all of our leases. ASC 842 permits a lessee, by class of underlying asset, not to separate nonlease components from lease components. Our policy is to apply this expedient for our leases of fleet vehicles, IT assets and railcars when calculating their respective lease liabilities. Lease costs for the years ended December 31, 2024 and December 31, 2023 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized as part of the cost of another asset. Income statement presentation for these costs (when ultimately recognized on the income statement) is also included: Year Ended December 31, (in millions) Income Statement Classification 2024 2023 Finance lease cost Amortization of right-of-use assets Depreciation and amortization $ 27.1 $ 32.0 Interest on lease liabilities Interest expense, net 13.5 8.6 Total finance lease cost 40.6 40.6 Operating lease cost Operation and maintenance 14.7 11.3 Total lease cost $ 55.3 $ 51.9 Our right-of-use assets and liabilities are presented in the following lines on the Consolidated Balance Sheets: At December 31, (in millions) Balance Sheet Classification 2024 2023 Assets Finance leases Net Property, Plant and Equipment $ 222.9 $ 184.3 Operating leases Deferred charges and other 26.4 32.9 Total leased assets $ 249.3 217.2 Liabilities Current Finance leases Current portion of long-term debt $ 22.9 23.8 Operating leases Other accruals 9.1 8.3 Noncurrent Finance leases Long-term debt, excluding amounts due within one year 223.3 181.6 Operating leases Other noncurrent liabilities and deferred credits 18.2 25.8 Total lease liabilities $ 273.5 $ 239.5 Other pertinent information related to leases was as follows: Year Ended December 31, (in millions) 2024 2023 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows used for finance leases $ 11.2 $ 9.3 Operating cash flows used for operating leases 14.5 11.1 Financing cash flows used for finance leases 26.9 33.1 Right-of-use assets obtained in exchange for lease obligations Finance leases 65.9 64.5 Operating leases $ 12.2 $ 5.6 December 31, 2024 December 31, 2023 Weighted-average remaining lease term (years) Finance leases 20.5 16.4 Operating leases 5.6 6.7 Weighted-average discount rate Finance leases 5.6 % 5.5 % Operating leases 4.5 % 4.3 % Maturities of our lease liabilities as of December 31, 2024 were as follows: As of December 31, 2024, (in millions) Total Finance Leases Operating Leases 2025 $ 44.6 $ 34.6 $ 10.0 2026 34.7 29.4 5.3 2027 28.5 24.2 4.3 2028 26.1 23.0 3.1 2029 21.5 19.0 2.5 Thereafter 304.9 299.2 5.7 Total lease payments 460.3 429.4 30.9 Less: Imputed interest (186.8) (183.2) (3.6) Total $ 273.5 $ 246.2 $ 27.3 Reported as of December 31, 2024 Short-term lease liabilities 32.0 22.9 9.1 Long-term lease liabilities 241.5 223.3 18.2 Total lease liabilities $ 273.5 $ 246.2 $ 27.3
Lessee, Finance Leases	Lease Descriptions. We are the lessee for substantially all of our leasing activity, which includes operating and finance leases for corporate and field offices, railcars, land, and fleet vehicles. Our corporate and field office leases and certain land leases have remaining terms between 1 and 39 years with options to renew the leases for up to 35 years. We lease railcars to transport coal to and from our electric generation facilities in Indiana. Our railcars are specifically identified in the lease agreements which have remaining lease terms between 1 and 3 years with options to renew for 1 year. Our fleet vehicles include trucks, trailers and equipment that have been customized specifically for use in the utility industry. We lease fleet vehicles for 1 year terms, after which we have the option to extend on a month-to-month basis or terminate with written notice. We elected the short-term lease practical expedient, allowing us to not recognize ROU assets or lease liabilities for all leases with a term of 12 months or less. ROU assets and liabilities on our Consolidated Balance Sheets do not include obligations for possible fleet vehicle lease renewals beyond the initial lease term. While we have the ability to renew these leases beyond the initial term, we are not reasonably certain to do so. We have not provided material residual value guarantees for our leases, nor do our leases contain material restrictions or covenants. Lease contracts containing renewal and termination options are mostly exercisable at our sole discretion. Certain of our real estate and railcar leases include renewal periods in the measurement of the lease obligation if we have deemed the renewals reasonably certain to be exercised. With respect to service contracts involving the use of assets, if we have the right to direct the use of the asset and obtain substantially all economic benefits from the use of an asset, we account for the service contract as a lease. Unless specifically provided to us by the lessor, we utilize NiSource's collateralized incremental borrowing rate commensurate to the lease term as the discount rate for all of our leases. ASC 842 permits a lessee, by class of underlying asset, not to separate nonlease components from lease components. Our policy is to apply this expedient for our leases of fleet vehicles, IT assets and railcars when calculating their respective lease liabilities. Lease costs for the years ended December 31, 2024 and December 31, 2023 are presented in the table below. These costs include both amounts recognized in expense and amounts capitalized as part of the cost of another asset. Income statement presentation for these costs (when ultimately recognized on the income statement) is also included: Year Ended December 31, (in millions) Income Statement Classification 2024 2023 Finance lease cost Amortization of right-of-use assets Depreciation and amortization $ 27.1 $ 32.0 Interest on lease liabilities Interest expense, net 13.5 8.6 Total finance lease cost 40.6 40.6 Operating lease cost Operation and maintenance 14.7 11.3 Total lease cost $ 55.3 $ 51.9 Our right-of-use assets and liabilities are presented in the following lines on the Consolidated Balance Sheets: At December 31, (in millions) Balance Sheet Classification 2024 2023 Assets Finance leases Net Property, Plant and Equipment $ 222.9 $ 184.3 Operating leases Deferred charges and other 26.4 32.9 Total leased assets $ 249.3 217.2 Liabilities Current Finance leases Current portion of long-term debt $ 22.9 23.8 Operating leases Other accruals 9.1 8.3 Noncurrent Finance leases Long-term debt, excluding amounts due within one year 223.3 181.6 Operating leases Other noncurrent liabilities and deferred credits 18.2 25.8 Total lease liabilities $ 273.5 $ 239.5 Other pertinent information related to leases was as follows: Year Ended December 31, (in millions) 2024 2023 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows used for finance leases $ 11.2 $ 9.3 Operating cash flows used for operating leases 14.5 11.1 Financing cash flows used for finance leases 26.9 33.1 Right-of-use assets obtained in exchange for lease obligations Finance leases 65.9 64.5 Operating leases $ 12.2 $ 5.6 December 31, 2024 December 31, 2023 Weighted-average remaining lease term (years) Finance leases 20.5 16.4 Operating leases 5.6 6.7 Weighted-average discount rate Finance leases 5.6 % 5.5 % Operating leases 4.5 % 4.3 % Maturities of our lease liabilities as of December 31, 2024 were as follows: As of December 31, 2024, (in millions) Total Finance Leases Operating Leases 2025 $ 44.6 $ 34.6 $ 10.0 2026 34.7 29.4 5.3 2027 28.5 24.2 4.3 2028 26.1 23.0 3.1 2029 21.5 19.0 2.5 Thereafter 304.9 299.2 5.7 Total lease payments 460.3 429.4 30.9 Less: Imputed interest (186.8) (183.2) (3.6) Total $ 273.5 $ 246.2 $ 27.3 Reported as of December 31, 2024 Short-term lease liabilities 32.0 22.9 9.1 Long-term lease liabilities 241.5 223.3 18.2 Total lease liabilities $ 273.5 $ 246.2 $ 27.3

Other Commitments And Contingen

Other Commitments And Contingencies	12 Months Ended
	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Other Commitments And Contingencies	Contractual Obligations . We have certain contractual obligations requiring payments at specified periods. The obligations include long-term debt, lease obligations, energy commodity contracts and obligations for various services including pipeline capacity and outsourcing of IT services. The total contractual obligations in existence at December 31, 2024 and their maturities were: (in millions) Total 2025 2026 2027 2028 2029 After Long-term debt (1) $ 13,205.0 $ 1,260.0 $ — $ 1,090.0 $ 1,055.0 $ 1,350.0 $ 8,450.0 Interest payments on long-term debt 8,090.3 566.2 551.1 531.7 481.6 453.9 5,505.8 Finance leases (2) 429.4 34.6 29.4 24.2 23.0 19.0 299.2 Operating leases (3) 30.9 10.0 5.3 4.3 3.1 2.5 5.7 Energy commodity contracts 119.7 118.5 0.3 0.3 0.4 0.2 — Service obligations: Pipeline service obligations 2,694.6 685.5 631.2 609.2 373.2 245.2 150.3 IT service obligations 120.7 73.9 30.3 11.4 5.1 — — Plant equipment purchase obligations 173.5 140.5 24.9 4.3 3.8 — — Other liabilities (4) 336.0 287.0 7.9 7.7 7.6 7.7 18.1 Total contractual obligations $ 25,200.1 $ 3,176.2 $ 1,280.4 $ 2,283.1 $ 1,952.8 $ 2,078.5 $ 14,429.1 (1) Long-term debt balance excludes unamortized issuance costs and discounts of $95.5 million. (2) Finance lease payments shown above are inclusive of interest totaling $183.2 million. (3) Operating lease payments shown above are inclusive of interest totaling $3.6 million. Operating lease balances do not include obligations for possible fleet vehicle lease renewals beyond the initial lease term. While we have the ability to renew these leases beyond the initial term, we are not reasonably certain to do so as they are renewed month-to-month after the first year. (4) Other liabilities shown above are primarily related to the Dunns Bridge II and Indiana Crossroads Solar Developer payments due in 2025 and ongoing maintenance service agreements for our renewable joint ventures. Purchase and Service Obligations. We have entered into various purchase and service agreements whereby we are contractually obligated to make certain minimum payments in future periods. Our energy commodity contracts are for the purchase of physical quantities of natural gas, electricity and coal. Our service obligations, consisting of pipeline service obligations and IT service obligations, encompass a broad range of business support and maintenance functions which are generally described below. Our plant equipment purchase obligations are for plant equipment, typically for generation assets, with long lead times that require payments made over time Our subsidiaries have entered into various energy commodity contracts to purchase physical quantities of natural gas, electricity and coal. These amounts represent the minimum quantity of these commodities we are obligated to purchase at both fixed and variable prices. To the extent contractual purchase prices are variable, obligations disclosed in the table above are valued at market prices as of December 31, 2024. NIPSCO has PPAs representing a total of 600 MW of wind power, with contracts expiring between 2038 and 2040. No minimum quantities are specified within these agreements due to the variability of electricity generation from wind, so no amounts related to these contracts are included in the table above. Upon early termination of one of these agreements by NIPSCO for any reason (other than material breach by the counterparties), NIPSCO may be required to pay a termination charge that could be material depending on the events giving rise to termination and the timing of the termination. We have pipeline service agreements that provide for pipeline capacity, transportation and storage services. These agreements, which have expiration dates ranging from 2028 to 2038, require us to pay fixed monthly charges. NIPSCO has contracts with three major rail operators providing coal transportation services for which there are certain minimum payments. These service contracts extend for various periods through 2025. We have executed agreements with multiple IT service providers. The agreements extend for various periods through 2029. B. Guarantees and Indemnities . We and certain of our subsidiaries enter into various agreements providing financial or performance assurance to third parties on behalf of certain subsidiaries as part of normal business. Such agreements include guarantees and stand-by letters of credit. These agreements are entered into primarily to support or enhance the creditworthiness otherwise attributed to a subsidiary on a stand-alone basis, thereby facilitating the extension of sufficient credit to accomplish the subsidiaries’ intended commercial purposes. At December 31, 2024 and 2023, we issued stand-by letters of credit of $9.4 million and $9.9 million, respectively, for the benefit of third parties. We provide guarantees related to our future performance under BTAs for our renewable generation projects. At December 31, 2024 and 2023, our guarantees for multiple BTAs totaled $1,127.5 million and $646.1 million, respectively. The amount of each guaranty will decrease upon completion of certain milestones for the construction of the facilities, including mechanical and substantial completion. See “- E. Other Matters - Generation Transition,” below for more information. We provide guarantees related to some of our rail and pipeline service agreements. If we do not meet our contractual obligations under the terms of these agreements we would be required to pay up to a maximum of $61.7 million. C. Legal Proceedings . From time to time, various legal and regulatory claims and proceedings are pending or threatened against the Company and its subsidiaries. While the amounts claimed may be substantial, the Company is unable to predict with certainty the ultimate outcome of such claims and proceedings. The Company establishes reserves whenever it believes it to be appropriate for pending litigation matters. However, the actual results of resolving the pending litigation matters may be substantially higher than the amounts reserved. If one or more other matters were decided against us, the effects could be material to our results of operations in the period in which we would be required to record or adjust the related liability and could also be material to our cash flows in the periods that we would be required to pay such liability. Due to the inherent uncertainty of litigation, there can be no assurance that the resolution of any particular claim, proceeding or investigation would not have a material adverse effect on our results of operations, financial position or liquidity. Other Claims and Proceedings. We are also party to certain other claims, regulatory and legal proceedings arising in the ordinary course of business in each state in which we have operations, and based upon an investigation of these matters and discussion with legal counsel, we believe the ultimate outcome of such other legal proceedings to be individually, or in aggregate, not material at this time. D. Environmental Matters . Our operations are subject to environmental statutes and regulations related to air quality, water quality, hazardous waste and solid waste. We believe that we are in substantial compliance with the environmental regulations currently applicable to our operations. It is management's continued intent to address environmental issues in cooperation with regulatory authorities in such a manner as to achieve mutually acceptable compliance plans. However, there can be no assurance that fines and penalties will not be incurred. Management expects the majority of environmental assessment and remediation costs and asset retirement costs, further described below, to be recoverable through rates. See Note 11, "Asset Retirement Obligations" and Note 12, "Regulatory Matters," for additional detail. As of December 31, 2024 and 2023, we had recorded a liability of $91.8 million and $80 million, respectively, to cover environmental remediation at various sites. This liability is included in "Other accruals" and "Other noncurrent liabilities and deferred credits" in the Consolidated Balance Sheets. We recognize costs associated with environmental remediation obligations when the incurrence of such costs is probable and the amounts can be reasonably estimated. The original estimates for remediation activities may differ materially from the amount ultimately expended. The actual future expenditures depend on many factors, including laws and regulations, the nature and extent of impact and the method of remediation. These expenditures are not currently estimable at some sites. We periodically adjust our liability as information is collected and estimates become more refined. CERCLA. Our subsidiaries are potentially responsible parties at waste disposal sites under the CERCLA and similar state laws. Under CERCLA, each potentially responsible party can be held jointly, severally and strictly liable for the remediation costs as the EPA, or state, can allow the parties to pay for remedial action or perform remedial action themselves and request reimbursement from the potentially responsible parties. Our affiliates have retained CERCLA environmental liabilities, including remediation liabilities, associated with certain current and former operations. At this time, we cannot estimate the full cost of remediating properties that have not yet been investigated, but it is possible that the future costs could be material to the Consolidated Financial Statements. MGP. We maintain a program to identify and investigate former MGP sites where gas distribution subsidiaries or predecessors may have liability. The program has identified 51 such sites where liability is probable. Remedial actions at many of these sites are being overseen by state or federal environmental agencies through consent agreements or voluntary remediation agreements. We utilize a probabilistic model to estimate our future remediation costs related to MGP sites. The model was prepared with the assistance of a third party and incorporates our experience and general industry experience with remediating MGP sites. We complete an annual refresh of the model in the second quarter of each fiscal year. We recorded an $11.2 million increase to the estimated future remediation costs as a result of the refresh completed in the second quarter of 2024. No material changes to the estimated future remediation costs were noted as a result of an internal quarterly review of environmental reserves completed as of December 31, 2024. Our total estimated liability related to the facilities subject to remediation was $86.4 million and $73.7 million at December 31, 2024 and 2023, respectively. The liability represents our best estimate of the probable cost to remediate the MGP sites. Our model indicates that it is reasonably possible that remediation costs could vary by as much as $16.3 million in addition to the costs noted above. Remediation costs are estimated based on the best available information, applicable remediation standards at the balance sheet date, and experience with similar facilities. CCRs. NIPSCO continues to meet the compliance requirements established by the EPA for the regulation of CCRs. The CCR rule requirements currently in effect required revisions to previously recorded legal obligations associated with the retirement of certain NIPSCO facilities. The actual asset retirement costs related to the CCR rule may vary substantially from the estimates used to record the increased asset retirement obligation due to the uncertainty about the requirements that will be established by environmental authorities, compliance strategies that will be used and the preliminary nature of available data used to estimate costs. As allowed by the rule, NIPSCO will continue to collect data over time to determine the specific compliance solutions and associated costs and, as a result, the actual costs may vary. E. Other Matters Generation Transition. NIPSCO has executed several BTAs with developers to construct renewable generation facilities. NIPSCO has received IURC approval for all of its BTAs and PPAs. In October 2024, NIPSCO contracted with a developer to convert the previously approved Templeton Wind PPA to a BTA and has provided a notice of intent to file a CPCN with the IURC. In addition to IURC approval, NIPSCO's purchase obligation under certain BTAs is dependent on timely completion of construction. Certain agreements require NIPSCO to make partial payments upon the developer's completion of significant construction milestones. With respect to BTAs for which tax equity partnerships are utilized, once the tax equity partner has earned its negotiated rate of return and we have reached the agreed upon contractual date, NIPSCO has the option to purchase at fair market value the remaining interest in the JV from the tax equity partner. In January 2024, the IURC approved the full ownership of Cavalry and Dunns Bridge II which will allow those BTAs to be executed through direct ownership. In March 2024, Cavalry achieved mechanical completion, resulting in NIPSCO making a $110.6 million payment to the developer. In May 2024, Cavalry achieved substantial completion and commenced commercial operations, resulting in NIPSCO making a $114.9 million payment to the developer. In August 2024, the IURC approved full ownership of the Gibson and Fairbanks projects as well as an increase to the cost of the Fairbanks project. In January 2025, Fairbanks achieved mechanical completion resulting in NIPSCO making a $336.6 million payment to the developer. In September 2024, Dunns Bridge II achieved mechanical completion, resulting in NIPSCO making a $153.3 million payment to the developer. In January 2025, substantial completion was achieved requiring a final payment of $217.6 million to be paid in February 2025. NIPSCO has filed a request to modify the ownership structure for the Templeton wind project to become a wholly owned project. NIPSCO Minority Interest Transaction . On December 31, 2023, pursuant to the terms of the BIP Purchase Agreement and simultaneously with the closing of the NIPSCO Minority Interest Transaction, Blackstone, NIPSCO Holdings I, NIPSCO Holdings II and NiSource entered into an Amended and Restated Limited Liability Company Agreement (the "LLC Agreement") of NIPSCO Holdings II. Specifically, under the terms of the LLC Agreement, Blackstone will provide up to $250 million in additional capital contributions over a three-year period after the closing, which the obligation is backed by an Equity Commitment Letter from an affiliate of Blackstone. Under the LLC Agreement, Blackstone is entitled to appoint two directors to the board of directors of NIPSCO Holdings II (the “Board”) so long as Blackstone (together with any approved affiliate) holds at least a 17.5% percentage interest (as defined in the LLC Agreement). In connection with the closing, Blackstone appointed two directors to the Board, such that the Board is now comprised of seven directors, two appointed by Blackstone and five appointed by NiSource. The LLC Agreement also contains certain investor protections, including, among other things, requiring Blackstone approval for Holdings II to take certain major actions. In addition, the LLC Agreement contains certain terms regarding transfer rights and other obligations applicable to both Blackstone and NiSource. The LLC Agreement establishes, among other things, governance rights, exit rights, requirements for additional capital contributions, mechanics for distributions, and other arrangements for Holdings II following the closing. On January 31, 2024, BIP transferred a 4.5% equity interest in NIPSCO Holdings II to BIP Blue Buyer VCOC L.L.C., a Delaware limited liability company and also an affiliate of Blackstone. Effective upon the closing of this transfer, the members of NIPSCO Holdings II entered into a Second Amended and Restated Limited Liability Company Operating Agreement of NIPSCO Holdings II (the "Amended LLC

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2024
Components of Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Loss	The following table displays the activity of Accumulated Other Comprehensive Loss, net of tax: (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2022 $ 2.1 $ (122.5) $ (6.4) $ (126.8) Other comprehensive (loss) income before reclassifications (13.7) 109.7 (8.9) 87.1 Amounts reclassified from accumulated other comprehensive loss 0.4 0.2 2.0 2.6 Net current-period other comprehensive (loss) income (13.3) 109.9 (6.9) 89.7 Balance as of December 31, 2022 $ (11.2) $ (12.6) $ (13.3) $ (37.1) Other comprehensive (loss) income before reclassifications 3.1 (0.5) (1.4) 1.2 Amounts reclassified from accumulated other comprehensive loss 0.8 0.3 1.2 2.3 Net current-period other comprehensive (loss) income 3.9 (0.2) (0.2) 3.5 Balance as of December 31, 2023 $ (7.3) $ (12.8) $ (13.5) $ (33.6) Other comprehensive income (loss) before reclassifications 1.5 — (1.2) 0.3 Amounts reclassified from accumulated other comprehensive loss 1.8 (0.4) 1.5 2.9 Net current-period other comprehensive income (loss) 3.3 (0.4) 0.3 3.2 Balance as of December 31, 2024 $ (4.0) $ (13.2) $ (13.2) $ (30.4) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Business Segment Information

Business Segment Information	12 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Business Segment Information	Our reportable segments reflect the manner in which our business is managed and our resources are allocated. Following the consummation of the NIPSCO Minority Interest Transaction, we revised how we evaluate results and allocate resources across our business with an increased focus on operating performance at the state level. Refer to Note 4, "Noncontrolling Interests," for additional information on the NIPSCO Minority Interest Transaction. At December 31, 2024, our operations are divided into two primary reportable segments, the Columbia Operations and the NIPSCO Operations segments. Columbia Operations aggregates the results of the fully regulated and wholly owned subsidiaries of NiSource Gas Distribution Group, Inc. (a holding company that owns Columbia of Kentucky, Columbia of Maryland, Columbia of Ohio, Columbia of Pennsylvania, and Columbia of Virginia). Each Columbia distribution company is an operating segment which we aggregate to form the Columbia Operations reportable segment. NIPSCO Operations includes the results of NIPSCO Holdings I and its majority-owned subsidiaries, including NIPSCO, which has fully regulated gas and electric operations in northern Indiana. Our historical segment disclosures have been recast to be consistent with the current presentation. The remainder of our operations, which are not significant enough on a stand-alone basis to warrant treatment as an operating segment, are presented as "Corporate and Other" in the subsequent reconciliation table and primarily are comprised of interest expense on holding company debt and unallocated corporate costs and activities. Refer to Note 3, "Revenue Recognition," for additional information on our segments and their sources of revenues. The following table provides information about our reportable segments. We use operating income as our primary measurement for each of the reported segments and make decisions on financing, dividends and taxes at the corporate level on a consolidated basis. We provide this measure to our Chief Operating Decision Maker, the CEO, who utilizes this measure to make operating segment level strategy decisions based on budget-to-actual variances and against prior periods to allocate resources accordingly. Segment revenues include intersegment sales to affiliated subsidiaries, which are eliminated in consolidation. Affiliated sales are recognized on the basis of prevailing market, regulated prices or at levels provided for under contractual agreements. Operating income is derived from revenues and expenses directly associated with each segment. Year Ended December 31, 2024 (in millions) Columbia Operations NIPSCO Operations Total of Reportable Segments Operating Revenues External Revenue $ 2,703.2 $ 2,751.0 $ 5,454.2 Intersegment Revenue 12.8 1.0 13.8 Total Operating Revenue $ 2,716.0 $ 2,752.0 $ 5,468.0 Cost of energy 514.7 617.5 1,132.2 O&M 837.5 761.4 1,598.9 Depreciation 409.1 590.3 999.4 Total other taxes 218.6 64.3 282.9 Other segment items (1) 7.4 (1.3) 6.1 Operating Income $ 728.7 $ 719.8 $ 1,448.5 Capital Expenditures (2) $ 1,209.0 $ 2,252.4 $ 3,461.4 Assets $ 14,769.5 $ 15,823.5 $ 30,593.0 (1) Other segment items consists of Loss (gain) on Sale or Impairment of Assets and other segment income or expenses deemed insignificant which are used to reach our measurement of segment profit or loss, Operating Income. (2) Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures in current liabilities, the capitalized portion of the Corporate Incentive Plan payout, and AFUDC Equity. Year Ended December 31, 2023 (in millions) Columbia Operations NIPSCO Operations Total of Reportable Segments Operating Revenues External Revenue $ 2,733.9 $ 2,770.7 $ 5,504.6 Intersegment Revenue 12.2 0.9 13.1 Total Operating Revenue $ 2,746.1 $ 2,771.6 $ 5,517.7 Cost of energy 645.0 888.3 1,533.3 O&M 792.3 787.7 1,580.0 Depreciation 371.7 493.8 865.5 Total other taxes 198.8 57.9 256.7 Other segment items (1) — 2.2 2.2 Operating Income $ 738.3 $ 541.7 $ 1,280.0 Capital Expenditures (2) $ 1,159.6 $ 1,294.8 $ 2,454.4 Assets $ 13,664.5 $ 13,962.6 $ 27,627.1 (1) Other segment items consists of Loss(gain) on Sale or Impairment of Assets and other segment income or expenses deemed insignificant which are used to reach our measurement of segment profit or loss, Operating Income. (2) Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures in current liabilities, the capitalized portion of the Corporate Incentive Plan payout, and AFUDC Equity. Year Ended December 31, 2022 (in millions) Columbia Operations NIPSCO Operations Total of Reportable Segments Operating Revenues External Revenue $ 2,951.9 $ 2,886.2 $ 5,838.1 Intersegment Revenue 12.5 0.9 13.4 Total Operating Revenue $ 2,964.4 $ 2,887.1 $ 5,851.5 Cost of energy 978.4 1,132.1 2,110.5 O&M 791.3 740.4 1,531.7 Depreciation 329.4 449.4 778.8 Total other taxes 184.2 72.1 256.3 Other segment items (1) (103.9) — (103.9) Operating Income $ 785.0 $ 493.1 $ 1,278.1 Capital Expenditures (2) $ 1,237.9 $ 1,018.9 $ 2,256.8 Assets $ 13,059.4 $ 11,759.9 $ 24,819.3 (1) Other segment items consists of proceeds from a property insurance settlement related to the Greater Lawrence Incident and other segment income or expenses deemed insignificant which are used to reach our measurement of segment profit or loss, Operating Income. (2) Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures in current liabilities, the capitalized portion of the Corporate Incentive Plan payout, and AFUDC Equity. To reconcile the segment tables above to consolidated NiSource: Year Ended December 31, 2024 (in millions) Total Reportable Segments Corporate and Other Eliminations Consolidated NiSource Total Operating Revenue $ 5,468.0 $ 581.9 $ (594.8) $ 5,455.1 Operating Income 1,448.5 7.0 — 1,455.5 Capital Expenditures 3,461.4 231.1 — 3,692.5 Assets 30,593.0 1,195.1 — 31,788.1 Year Ended December 31, 2023 (in millions) Total Reportable Segments Corporate and Other Eliminations Consolidated NiSource Total Operating Revenue $ 5,517.7 $ 504.6 $ (516.9) $ 5,505.4 Operating Income 1,280.0 15.5 — 1,295.5 Capital Expenditures 2,454.4 236.3 — 2,690.7 Assets 27,627.1 3,450.1 — 31,077.2 Year Ended December 31, 2022 (in millions) Total Reportable Segments Corporate and Other Eliminations Consolidated NiSource Total Operating Revenue $ 5,851.5 $ 477.5 $ (478.4) $ 5,850.6 Operating Income (Loss) 1,278.1 (12.3) — 1,265.8 Capital Expenditures 2,256.8 41.2 — 2,298.0 Assets 24,819.3 1,917.3 — 26,736.6

Other, Net

Other, Net	12 Months Ended
	Dec. 31, 2024
Other Nonoperating Income (Expense) [Abstract]
Other, Net	Year Ended December 31, (in millions) 2024 2023 2022 Interest income $ 10.4 $ 9.0 $ 4.3 AFUDC equity 75.1 25.2 15.1 Charitable contributions (5.4) (1.8) (4.4) Pension and other postretirement non-service cost (1) (13.5) (24.0) 27.6 Interest rate swap settlement gain — — 10.0 Miscellaneous (2.1) (0.4) (0.4) Total Other, net $ 64.5 $ 8.0 $ 52.2 (1) See Note 16, "Pension and Other Postemployment Benefits," for additional information.

Interest Expense, Net

Interest Expense, Net	12 Months Ended
	Dec. 31, 2024
Interest Expense, Operating and Nonoperating [Abstract]
Interest Expense, Net	The following table displays the components of Interest Expense, Net included on the Statements of Consolidated Income: Year Ended December 31, (in millions) 2024 2023 2022 Interest on long-term debt $ 506.2 $ 404.1 $ 344.5 Interest on short-term borrowings 43.2 108.9 22.7 Debt discount/cost amortization 13.8 13.5 11.7 Accounts receivable securitization fees 1.5 2.7 2.5 Allowance for borrowed funds used and interest capitalized during construction (40.1) (25.3) (6.7) Debt-based post-in-service carrying charges (26.4) (30.7) (21.1) Other 19.0 16.4 8.0 Total Interest Expense, net $ 517.2 $ 489.6 $ 361.6

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2024
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	The following table provides additional information regarding our Consolidated Statements of Cash Flows for the years ended December 31, 2024, 2023 and 2022: Year Ended December 31, (in millions) 2024 2023 2022 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities $ 367.0 $ 315.0 $ 275.1 Assets acquired under a finance lease 65.9 64.5 19.3 Assets acquired under an operating lease 12.2 5.6 8.8 Assets recorded for asset retirement obligations (1) 277.4 61.1 6.3 Purchase contract liability, net of fees and payments (2) — — 65.0 Schedule of interest and income taxes paid: Cash paid for interest on debt, net of interest capitalized amounts $ 468.2 $ 433.9 $ 343.8 Cash paid for interest on finance leases 11.2 8.6 8.5 Cash paid for income taxes, net of refunds 4.3 9.4 7.2 (1) See Note 11, "Asset Retirement Obligations," for additional information. (2) Refer to Note 6, "Equity," for additional information.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss) Attributable to NiSource	$ 760.4	$ 714.3	$ 804.1

Insider Trading Arrangements

Insider Trading Arrangements	12 Months Ended
	Dec. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	The following table describes any contracts, instructions or written plans for the sale or purchase of NiSource securities and intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) of the Exchange Act that were adopted by our directors and executive officers during the year ended December 31, 2024: Name and Title Date of Adoption of Rule 10b-5-1 Trading Plan Scheduled Expiration Date of Rule 10b5-1 Trading Plan (1) Aggregate Number of Securities to Be Purchased or Sold Shawn Anderson Executive Vice President, Chief Financial Officer 11/1/2024 5/30/2025 Sale of up to 12,900 shares of common stock in multiple transactions Michael Jesanis Director 11/11/2024 5/16/2025 Sale of up to 10,092 shares of common stock in multiple transactions (1) A trading plan may also expire on such earlier date that all transactions under the trading plan are completed.
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Shawn Anderson [Member]
Trading Arrangements, by Individual
Name	Shawn Anderson
Title	Executive Vice President, Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	11/1/2024
Expiration Date	5/30/2025
Arrangement Duration	210 days
Aggregate Available	12,900
Michael Jesanis [Member]
Trading Arrangements, by Individual
Name	Michael Jesanis
Title	Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	11/11/2024
Expiration Date	5/16/2025
Arrangement Duration	196 days
Aggregate Available	10,092

Insider Trading Policies and Pr

Insider Trading Policies and Procedures	12 Months Ended
	Dec. 31, 2024
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Cybersecurity Risk Management a

Cybersecurity Risk Management and Strategy Disclosure	12 Months Ended
	Dec. 31, 2024
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	NiSource has implemented and maintains a comprehensive cybersecurity program that includes a variety of security controls and measures designed to identify, assess, and manage material cybersecurity risks. The program is a part of NiSource’s enterprise risk management strategy. The enterprise risk team and the Risk Management Committee review material risks to any NiSource operating company based on perspectives from external experts, peer surveys, and the potential impact to NiSource’s enterprise assets and strategic objectives. Risk events are classified based on both the timing of impact and NiSource’s ability to preventatively mitigate the risk. For the cybersecurity risks that can be preventively mitigated, the enterprise risk team gathers quarterly updates on mitigation gap closure from risk owners. The Risk Management Committee reviews any mitigation gaps identified by risk owners and approves or rejects the pace of mitigation activities as a statement of risk tolerance and then directs that mitigation activities be included in budgets and the business plan as appropriate. The NiSource cybersecurity program includes the following key components: Risk assessment. NiSource regularly assesses its cybersecurity risks to identify and prioritize the most significant threats. The risk assessment process considers a variety of factors, including those specific to the utility/energy industry, the types of data NiSource collects and stores, and the threats posed by known vulnerabilities. NiSource engages third parties to perform independent assessments of its cybersecurity program, provide intelligence about the threat environment, and to provide operational assistance in managing the program. Annually, a third-party independent assessment is performed to evaluate NiSource cybersecurity maturity against a framework of cybersecurity controls. NiSource also performs bi-annual penetration testing and social engineering assessments performed by a third-party. Third-party risk management. NiSource performs cyber assessments periodically on third-party vendors and service providers with whom NiSource shares data, relies on for critical business functions, or provides access to the NiSource network or systems. NiSource’s Supply Chain function works with the Legal and Cyber functions to periodically update cybersecurity contractual provisions in its vendor agreements, with deviations from such provisions requiring approval from the Legal and Cyber functions. NiSource’s Supplier Code of Business Conduct requires, among other things, that suppliers ensure safe and secure use of information assets, comply with applicable law relating to personal information, and adhering to standards relative to the use and protection of Company information, including that of our employees, customers, vendors and other stakeholders. In addition, all vendors and contractors that have access and/or connectivity to the NiSource environment must complete cybersecurity training annually. Security controls. NiSource has implemented a variety of security controls to mitigate cybersecurity risks. These controls include technical controls, such as firewalls and intrusion detection systems, as well as administrative controls, such as employee training and security awareness programs. To ensure cybersecurity controls, NiSource OT within the electric business adheres to the NERC CIP. Within the natural gas business, cybersecurity controls are managed and monitored based on the TSA Security Directives. Incident response.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	NiSource has implemented and maintains a comprehensive cybersecurity program that includes a variety of security controls and measures designed to identify, assess, and manage material cybersecurity risks. The program is a part of NiSource’s enterprise risk management strategy. The enterprise risk team and the Risk Management Committee review material risks to any NiSource operating company based on perspectives from external experts, peer surveys, and the potential impact to NiSource’s enterprise assets and strategic objectives.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	The NiSource Board of Directors' Audit Committee has responsibility for oversight of the cybersecurity program and risks from cybersecurity threats. The Audit Committee regularly reviews NiSource’s cybersecurity posture. The CISO briefs the Audit Committee on cybersecurity risks and risk mitigation initiatives and actions. In addition, the Board of Directors remains informed of key and emerging cybersecurity risks and receives updates by the Audit Committee after each of its regularly scheduled meetings. At the management level, the CISO leads the cybersecurity program and is responsible for assessing and managing cybersecurity risks. Our CISO has expertise and experience in cybersecurity derived from over 15 years of cyber related work experience and possesses several certifications including CISSP, CRISC, and CISA. The CISO is supported by the NiSource Enterprise Security team which performs the cybersecurity function and engages directly on the prevention, detection, mitigation, and remediation of cybersecurity incidents. As of the date of filing this Annual Report on Form 10-K, NiSource is not aware of any material cybersecurity incidents during the past year. NiSource monitors the increasing sophistication of cybersecurity threats and continues to allocate resources to enhance its cybersecurity program to protect its information systems and assets. No cybersecurity program is effective to identify and mitigate all threats and NiSource cannot guarantee that it will be able to prevent all cybersecurity incidents. Such an incident could interrupt our normal operations and require us to incur significant costs to remediate any such incident and could have a material impact on our businesses, operations and financial condition. For more information regarding the risks associated with cybersecurity, refer to “Item 1A. Risk Factors” of this Annual Report on Form 10-K.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	The NiSource Board of Directors' Audit Committee has responsibility for oversight of the cybersecurity program and risks from cybersecurity threats. The Audit Committee regularly reviews NiSource’s cybersecurity posture. The CISO briefs the Audit Committee on cybersecurity risks and risk mitigation initiatives and actions. In addition, the Board of Directors remains informed of key and emerging cybersecurity risks and receives updates by the Audit Committee after each of its regularly scheduled meetings
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	The NiSource Board of Directors' Audit Committee has responsibility for oversight of the cybersecurity program and risks from cybersecurity threats. The Audit Committee regularly reviews NiSource’s cybersecurity posture. The CISO briefs the Audit Committee on cybersecurity risks and risk mitigation initiatives and actions. In addition, the Board of Directors remains informed of key and emerging cybersecurity risks and receives updates by the Audit Committee after each of its regularly scheduled meetings.
Cybersecurity Risk Role of Management [Text Block]	At the management level, the CISO leads the cybersecurity program and is responsible for assessing and managing cybersecurity risks. Our CISO has expertise and experience in cybersecurity derived from over 15 years of cyber related work experience and possesses several certifications including CISSP, CRISC, and CISA. The CISO is supported by the NiSource
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	The NiSource Board of Directors' Audit Committee has responsibility for oversight of the cybersecurity program and risks from cybersecurity threats. The Audit Committee regularly reviews NiSource’s cybersecurity posture. The CISO briefs the Audit Committee on cybersecurity risks and risk mitigation initiatives and actions. In addition, the Board of Directors remains informed of key and emerging cybersecurity risks and receives updates by the Audit Committee after each of its regularly scheduled meetings. At the management level, the CISO leads the cybersecurity program and is responsible for assessing and managing cybersecurity risks. Our CISO has expertise and experience in cybersecurity derived from over 15 years of cyber related work experience and possesses several certifications including CISSP, CRISC, and CISA. The CISO is supported by the NiSource
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Our CISO has expertise and experience in cybersecurity derived from over 15 years of cyber related work experience and possesses several certifications including CISSP, CRISC, and CISA. The CISO is supported by the NiSource Enterprise Security team which performs the cybersecurity function and engages directly on the prevention, detection, mitigation, and remediation of cybersecurity incidents.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The NiSource Board of Directors' Audit Committee has responsibility for oversight of the cybersecurity program and risks from cybersecurity threats. The Audit Committee regularly reviews NiSource’s cybersecurity posture. The CISO briefs the Audit Committee on cybersecurity risks and risk mitigation initiatives and actions. In addition, the Board of Directors remains informed of key and emerging cybersecurity risks and receives updates by the Audit Committee after each of its regularly scheduled meetings. At the management level, the CISO leads the cybersecurity program and is responsible for assessing and managing cybersecurity risks. Our CISO has expertise and experience in cybersecurity derived from over 15 years of cyber related work experience and possesses several certifications including CISSP, CRISC, and CISA. The CISO is supported by the NiSource
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Nature of Operations And Summ_2

Nature of Operations And Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Company Structure And Principles Of Consolidation	Company Structure and Principles of Consolidation. We are an energy holding company incorporated in Delaware and headquartered in Merrillville, Indiana. Our subsidiaries are fully regulated natural gas and electric utility companies serving approximately 3.8 million customers in six states. We generate substantially all of our operating income through these rate-regulated businesses. The consolidated financial statements include the accounts of us, our majority-owned subsidiaries, and VIEs of which we are the primary beneficiary after the elimination of all intercompany accounts and transactions.
Use Of Estimates	Use of Estimates. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Cash, Cash Equivalents, And Restricted Cash	Cash, Cash Equivalents and Restricted Cash. We consider all highly liquid investments with original maturities of three months or less to be cash equivalents. We report amounts deposited in brokerage accounts for margin requirements as restricted cash. In addition, we have amounts deposited in trusts to satisfy requirements for the provision of various property, liability, workers compensation, and long-term disability insurance, and holdbacks related to certain joint venture development agreements which is classified as restricted cash on the Consolidated Balance Sheets and disclosed with cash and cash equivalents on the Statements of Consolidated Cash Flows.
Accounts Receivable And Unbilled Revenue	Accounts Receivable and Unbilled Revenue. Accounts receivable on the Consolidated Balance Sheets includes both billed and unbilled amounts. Unbilled amounts of accounts receivable relate to a portion of a customer’s consumption of gas or electricity from their last cycle billing date through the last day of the month (balance sheet date). Factors taken into consideration when estimating unbilled revenue include historical usage, customer rates, weather and reasonable and supportable forecasts. Accounts receivable fluctuates from year to year depending in large part on weather impacts and price volatility. Our accounts receivable on the Consolidated Balance Sheets include unbilled revenue, less reserves. The reserve for uncollectible receivables is our best estimate of the amount of probable credit losses in the existing accounts receivable. We determined the reserve based on historical collection experience, current market conditions and reasonable and supportable forecasts. Account balances are charged against the allowance when it is anticipated the receivable will not be recovered. Refer to Note 3, "Revenue Recognition," for additional information on customer-related accounts receivable, including amounts related to unbilled revenues.
Investments In Debt And Equity Securities	Investments in Debt Securities. Our investments in debt securities are carried at fair value and are designated as available-for-sale. These investments are included within “Available-for-sale debt securities” on the Consolidated Balance Sheets. Unrealized gains and losses, net of deferred income taxes, are recorded to accumulated other comprehensive income or loss. At each reporting period these investments are qualitatively and quantitatively assessed to determine whether a decline in fair value below the amortized cost basis has resulted from a credit loss or other factors. Impairments related to credit loss are recorded through an allowance for credit losses. Impairments that are not related to credit losses are included in other comprehensive income and are reflected in the Statements of Consolidated Income. No material impairment charges were recorded for the years ended December 31, 2024, 2023 or 2022. Refer to Note 14, "Fair Value," for additional information.
Basis Of Accounting For Rate-Regulated Subsidiaries	Basis of Accounting for Rate-Regulated Subsidiaries. Rate-regulated subsidiaries account for and report assets and liabilities consistent with the economic effect of the way in which regulators establish rates, if the rates established are designed to recover the costs of providing the regulated service and it is probable that such rates can be billed and collected. Certain expenses and credits subject to utility regulation or rate determination that would normally be reflected in income for non-regulated entities are deferred on the Consolidated Balance Sheets and are later recognized in income as the related amounts are included in customer rates and recovered from or refunded to customers. We continually evaluate whether or not our operations are within the scope of ASC 980 and rate regulations. As part of that analysis, we evaluate probability of recovery for our regulatory assets. In management’s opinion, our regulated subsidiaries will be subject to regulatory accounting for the foreseeable future. Refer to Note 12, "Regulatory Matters," for additional information.
Utility Plant And Other Property And Related Depreciation And Maintenance	Plant and Other Property and Related Depreciation and Maintenance. Property, plant and equipment (principally utility plant) is stated at cost. Our rate-regulated subsidiaries record depreciation using composite rates on a straight-line basis over the remaining service lives of the electric, gas and common properties, as approved by the appropriate regulators. Non-utility property, consisting of renewable generation assets owned by JVs of which we are the primary beneficiary and certain retired regulatory assets described below, is generally depreciated over the life of the associated assets. Refer to Note 9, "Property, Plant and Equipment," for additional information related to depreciation expense. For rate-regulated companies where provided for in rates, AFUDC is capitalized on all classes of property except organization costs, land, autos, office equipment, tools and other general property purchases. The allowance is applied to construction costs for that period of time between the date of the expenditure and the date on which such project is placed in service. Our consolidated pre-tax rate for AFUDC was 4.8% in 2024, 3.9% in 2023 and 3.4% in 2022. Generally, our subsidiaries follow the practice of charging maintenance and repairs, including the cost of removal of minor items of property, to expense as incurred. When our subsidiaries retire regulated property, plant and equipment, original cost plus the cost of retirement, less salvage value, is charged to accumulated depreciation. However, when it becomes probable a regulated asset will be retired substantially in advance of its original expected useful life or is abandoned, the cost of the asset and the corresponding accumulated depreciation is recognized as a separate asset. If the asset is still in operation, the gross amounts are classified as "Non-Utility and Other " as described in Note 9, "Property, Plant and Equipment." If the asset is no longer operating but still subject to recovery, the net amount is classified in "Regulatory assets" on the Consolidated Balance Sheets. If we are able to recover a full return of and on investment, the carrying value of the asset is based on historical cost. If we are not able to recover a full return on investment, a loss on impairment is recognized to the extent the net book value of the asset exceeds the present value of future revenues discounted at the incremental borrowing rate.
Goodwill And Other Intangible Assets	Goodwill and Other Intangible Assets. Substantially all of our goodwill relates to the excess of cost over the fair value of the net assets acquired in the Columbia acquisition on November 1, 2000. We test our goodwill for impairment annually as of May 1, or more frequently if events and circumstances indicate that goodwill might be impaired. Fair value of our reporting units is determined using a combination of income and market approaches. See Note 10, "Goodwill," for additional information.
Accounts Receivable Transfer Program	Accounts Receivable Transfer Programs. Certain of our subsidiaries have agreements with third parties to transfer certain accounts receivable without recourse. These transfers of accounts receivable are accounted for as secured borrowings. The entire gross receivables balance remains on the December 31, 2024 and 2023 Consolidated Balance Sheets. When amounts are securitized, the short-term debt is recorded in the amount of proceeds received from the transferees involved in the transactions. Refer to Note 7, "Short-Term Borrowings," for further information.
Fuel Adjustment Clause	Gas Cost and Fuel Adjustment Clause. Our regulated subsidiaries defer most differences between gas and fuel purchase costs and the recovery of such costs in revenues and adjust future billings for such deferrals on a basis consistent with applicable state-approved tariff provisions. These deferred balances are recorded as "Regulatory assets" or "Regulatory liabilities," as appropriate, on the Consolidated Balance Sheets. Refer to Note 12, "Regulatory Matters," for additional information.
Gas Inventory	Gas Storage and Other Inventories. Both the LIFO inventory methodology and the weighted average cost methodology are used to value natural gas in storage, as approved by regulators for all of our regulated subsidiaries. Inventory valued using LIFO was $43.8 million and $43.9 million at December 31, 2024 and 2023, respectively. Based on the average cost of gas using the LIFO method, the estimated replacement cost of gas in storage was less than the stated LIFO cost by $12.8 million at December 31, 2024 and was less than the stated LIFO cost by $22.5 million at December 31, 2023. As all LIFO inventory costs are collected from customers through our rate-regulated subsidiaries, no inventory impairment has been recorded. Gas inventory valued using the weighted average cost methodology was $135.8 million at December 31, 2024 and $222.0 million at December 31, 2023. Electric production fuel is valued using the weighted average cost inventory methodology, as approved by NIPSCO's regulator. Materials and supplies are valued using the weighted average cost inventory methodology. Materials and supplies are charged to expense or capitalized to property, plant and equipment when issued.
Accounting For Exchange And Balancing Arrangements Of Natural Gas	Accounting for Exchange and Balancing Arrangements of Natural Gas. Our Columbia Operations and NIPSCO Operations segment enters into balancing and exchange arrangements of natural gas as part of its operations and off-system sales programs. We record a receivable or payable for any of our respective cumulative gas imbalances, as well as for any gas inventory borrowed or lent under an exchange agreement. Exchange gas is valued based on individual regulatory jurisdiction requirements (for example, historical spot rate, spot at the beginning of the month). These receivables and payables are recorded as “Exchange gas receivable” or “Exchange gas payable” on our Consolidated Balance Sheets, as appropriate.
Accounting For Risk Management Activities	Accounting for Risk Management Activities. We account for our derivatives and hedging activities in accordance with ASC 815. We recognize all derivatives as either assets or liabilities on the Consolidated Balance Sheets at fair value, unless such contracts are exempted as a normal purchase normal sale under the provisions of the standard. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and resulting designation. We do not offset the fair value amounts recognized for any of our derivative instruments against the fair value amounts recognized for the right to reclaim cash collateral or obligation to return cash collateral for derivative instruments executed with the same counterparty under a master netting arrangement. See Note 13, "Risk Management Activities," for additional information.
Income Taxes And Investment Tax Credits	Income Taxes and Investment Tax Credits. Under the asset and liability method, deferred income taxes are provided for the tax consequences of temporary differences by applying enacted statutory tax rates applicable to future years to differences between the financial statement carrying amount and the tax basis of existing assets and liabilities. Investment tax credits associated with regulated operations are deferred and amortized as a reduction to income tax expense over the estimated useful lives of the related properties. Furthermore, the tax basis of the asset is reduced by 50% of the ITCs received, resulting in a net deferred tax asset. To the extent certain deferred income taxes of the regulated companies are recoverable or payable through future rates, regulatory assets and liabilities have been established. Regulatory assets for income taxes are primarily attributable to property-related tax timing differences for which deferred taxes had not been provided in the past when regulators did not recognize such taxes as costs in the rate-making process. Regulatory liabilities for income taxes are primarily attributable to the regulated companies’ obligation to refund to ratepayers deferred income taxes provided at rates higher than the current Federal income tax rate. Such property-related amounts are credited to ratepayers using either the average rate assumption method or the reverse South Georgia method. Non property-related amounts are credited to ratepayers consistent with state utility commission direction.
Environmental Expenditures	Environmental Expenditures. We accrue for costs associated with environmental remediation obligations, including expenditures related to asset retirement obligations and cost of removal, when the incurrence of such costs is probable and the amounts can be reasonably estimated, regardless of when the expenditures are actually made. The estimated future expenditures are based on currently enacted laws and regulations, existing technology and estimated site-specific costs where assumptions may be made about the nature and extent of site contamination, the extent of cleanup efforts, costs of alternative cleanup methods and other variables. The liability is adjusted as further information is discovered or circumstances change. The accruals for estimated environmental expenditures are recorded on the Consolidated Balance Sheets in “Other accruals” for short-term portions of these liabilities and “Other noncurrent liabilities and deferred credits” for the respective long-term portions of these liabilities. Rate-regulated subsidiaries applying regulatory accounting establish regulatory assets on the Consolidated Balance Sheets to the extent that future recovery of environmental remediation costs is probable through the regulatory process. Refer to Note 11, "Asset Retirement Obligations," and Note 19, "Other Commitments and Contingencies," for further information.
Excise Taxes	Excise Taxes. As an agent for some state and local governments, we invoice and collect certain excise taxes levied by state and local governments on customers and record these amounts as liabilities payable to the applicable taxing jurisdiction. Such balances are presented within "Other accruals" on the Consolidated Balance Sheets. These types of taxes collected from customers, comprised largely of sales taxes, are presented on a net basis affecting neither revenues nor cost of sales. We account for excise taxes for which we are liable by recording a liability for the expected tax with a corresponding charge to “Other taxes” expense on the Statements of Consolidated Income.
Accrued Insurance Liabilities	Accrued Insurance Liabilities. We accrue for insurance costs related to workers compensation, automobile, property, general and employment practices liabilities based on the most probable value of each claim. In general, claim values are determined by professional, licensed loss adjusters who consider the facts of the claim, anticipated indemnification and legal expenses, and respective state rules. Claims are reviewed by us at least quarterly and an adjustment is made to the accrual based on the most current information.
Pension Remeasurement	Pension Remeasurement. We utilize a third-party actuary for the purpose of performing actuarial valuations of our defined benefit plans. Annually, as of December 31, we perform a remeasurement for our defined benefit plans. Quarterly, we monitor for significant events, and if a significant event is identified, we perform a qualitative and quantitative assessment to determine if the resulting remeasurement would materially impact the NiSource financial statements. If material, an interim remeasurement is performed. See Note 16, "Pension and Other Postemployment Benefits," for additional information.
VIEs and Allocation of Earnings	. We maintain a controlling financial interest in certain of our less than wholly owned subsidiaries. We consolidate these subsidiaries as either voting interest entities or VIEs and present the third-party investors' portion of our net income (loss), net assets and comprehensive income (loss) as noncontrolling interest. Noncontrolling interest is included as a component of equity on the Consolidated Balance Sheet. On December 31, 2023, the NIPSCO Minority Interest Transaction closed and a 19.9% equity interest in NIPSCO Holdings II, the sole owner of NIPSCO, was issued to an affiliate of Blackstone. NIPSCO Holdings II does not meet the criteria of a VIE and instead is consolidated under the voting interest model in accordance with ASC 810 as we maintain control through a majority interest in NIPSCO Holdings II. Refer to Note 4, "Noncontrolling Interests," for further discussion on the NIPSCO Minority Interest Transaction. We fund a portion of our renewable generation assets through JVs with tax equity partners. We consolidate these JVs in accordance with ASC 810 as they are VIEs in which we hold a variable interest, and we control decisions that are significant to the JVs' ongoing operations and economic results (i.e., we are the primary beneficiary). These JVs are subject to profit sharing arrangements in which the allocation of the JVs' cash distributions and tax benefits to members is based on factors other than members' relative ownership percentages. As such, we utilize the HLBV method to allocate proceeds to each partner at the balance sheet date based on the liquidation provisions of the related JV's operating agreement and adjust the amount of the VIE's net income attributable to us and the noncontrolling tax equity member during the period. In each reporting period, the application of HLBV to our consolidated VIEs results in a difference between the amount of profit from the consolidated JVs and the amount included in regulated rates. As discussed above in "F. Basis of Accounting for Rate-Regulated Subsidiaries," we are subject to the accounting and reporting requirements of ASC 980. In accordance with these principles, we recognize a regulatory liability or asset for amounts representing the timing difference between the profit earned from the JVs and the amount included in regulated rates to recover our approved investments in consolidated JVs. The amounts recorded in income will ultimately reflect the amount allowed in regulated rates to recover our investments over the useful life of the projects. The offset to the regulatory liability or asset associated with our renewable investments included in regulated rates is recorded in "Depreciation expense" on the Statements of Consolidated Income.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The tables below reconcile revenue disaggregation by customer class to segment revenue, as well as to revenues reflected on the Statements of Consolidated Income: Year Ended December 31, 2024 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Gas Distribution Residential $ 1,833.8 $ 531.4 $ — $ 2,365.2 Commercial 580.3 199.2 — 779.5 Industrial 144.2 79.0 — 223.2 Off-system 42.6 — — 42.6 Wholesale 1.2 — — 1.2 Miscellaneous (1) 26.3 15.4 — 41.7 Subtotal $ 2,628.4 $ 825.0 $ — $ 3,453.4 Electric Generation and Power Delivery Residential $ — $ 649.9 $ — $ 649.9 Commercial — 620.4 — 620.4 Industrial — 499.1 — 499.1 Wholesale — 38.3 — 38.3 Public Authority — 8.1 — 8.1 Miscellaneous (1) — 13.7 — 13.7 Subtotal $ — $ 1,829.5 $ — $ 1,829.5 Total Customer Revenues (2) 2,628.4 2,654.5 — 5,282.9 Other Revenues (3) 74.8 96.5 0.9 172.2 Total Operating Revenues $ 2,703.2 $ 2,751.0 $ 0.9 $ 5,455.1 (1) Amounts included in Columbia Operations are primarily related to earnings sharing mechanisms and late fees. Amounts included in NIPSCO Operations are primarily related to revenue refunds, public repairs and property rentals. (2) Customer revenue amounts exclude intersegment revenues. See Note 21, "Business Segment Information," for discussion of intersegment revenues. (3) Amounts included in Columbia Operations primarily relate to weather normalization adjustment mechanisms. Amounts included in NIPSCO Operations primarily relate to weather normalization adjustment mechanisms, MISO multi-value projects and revenue from non-jurisdictional transmission assets. Year Ended December 31, 2023 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Gas Distribution Residential $ 1,827.5 $ 635.0 $ — $ 2,462.5 Commercial 598.9 249.0 — 847.9 Industrial 139.0 87.0 — 226.0 Off-system 60.6 — — 60.6 Wholesale 1.6 — — 1.6 Miscellaneous (1) 33.4 14.8 — 48.2 Subtotal 2,661.0 985.8 — 3,646.8 Electric Generation and Power Delivery Residential — 583.9 — 583.9 Commercial — 578.1 — 578.1 Industrial — 474.1 — 474.1 Wholesale — 32.0 — 32.0 Public Authority — 11.5 — 11.5 Miscellaneous (1) — 21.4 — 21.4 Subtotal — 1,701.0 — 1,701.0 Total Customer Revenues (2) $ 2,661.0 $ 2,686.8 $ — $ 5,347.8 Other Revenues (3) 72.9 83.9 0.8 157.6 Total Operating Revenues $ 2,733.9 $ 2,770.7 $ 0.8 $ 5,505.4 (1) Amounts included in Columbia Operations are primarily related to earnings sharing mechanisms and late fees. Amounts included in NIPSCO Operations are primarily related to late fees, property rentals, revenue refunds, and adjustments. (2) Customer revenue amounts exclude intersegment revenues. See Note 21, "Business Segment Information," for discussion of intersegment revenues. (3) Amounts included in Columbia Operations primarily related to weather normalization adjustment mechanisms. Amounts included in NIPSCO Operations primarily related to MISO multi-value projects and revenue from non-jurisdictional transmission assets. Year Ended December 31, 2022 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Gas Distribution Residential $ 1,918.2 $ 691.5 $ — $ 2,609.7 Commercial 672.2 267.4 — 939.6 Industrial 135.5 85.1 — 220.6 Off-system 192.9 — — 192.9 Wholesale 2.1 — — 2.1 Miscellaneous (1) 27.3 10.9 — 38.2 Subtotal $ 2,948.2 $ 1,054.9 $ — $ 4,003.1 Electric Generation and Power Delivery Residential $ — $ 592.4 $ — $ 592.4 Commercial — 571.0 — 571.0 Industrial — 560.6 — 560.6 Wholesale — 13.5 — 13.5 Public Authority — 12.1 — 12.1 Miscellaneous (1) — (14.1) — (14.1) Subtotal $ — $ 1,735.5 $ — $ 1,735.5 Total Customer Revenues (2) $ 2,948.2 $ 2,790.4 $ — $ 5,738.6 Other Revenues (3) 3.7 95.8 12.5 112.0 Total Operating Revenues $ 2,951.9 $ 2,886.2 $ 12.5 $ 5,850.6 (1) Amounts included in Columbia Operations are primarily related to earnings share mechanisms and late fees. Amounts included in NIPSCO Operations are primarily related to revenue trackers, late fees and property rentals.2.1 (2) Customer revenue amounts exclude intersegment revenues. See Note 21, "Business Segment Information," for discussion of intersegment revenues. (3) Amounts included in Columbia Operations primarily related to weather normalization adjustment mechanisms. Amounts included in NIPSCO Operations primarily related to MISO multi-value projects and revenue from non-jurisdictional transmission assets. Amounts included in Corporate and Other primarily related to the Transition Services Agreement entered into in connection with the sale of the Massachusetts Business.
Customer Accounts Receivable	The opening and closing balances of customer receivables for the year ended December 31, 2024, are presented in the table below. We had no significant contract assets or liabilities during the period. Additionally, we have not incurred any significant costs to obtain or fulfill contracts. (in millions) Customer Accounts Receivable, Billed (less reserve) Customer Accounts Receivable, Unbilled (less reserve) Balance as of December 31, 2023 $ 479.4 $ 337.6 Balance as of December 31, 2024 525.1 408.1
Financing Receivable, Allowance for Credit Loss	A rollforward of our allowance for credit losses as of December 31, 2024 and December 31, 2023, are presented in the tables below: (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Balance as of January 1, 2024 $ 10.2 $ 11.9 $ 0.8 $ 22.9 Current period provisions 26.7 12.1 — 38.8 Write-offs charged against allowance (43.9) (11.0) (0.8) (55.7) Recoveries of amounts previously written off 16.8 0.9 — 17.7 Balance as of December 31, 2024 $ 9.8 $ 13.9 $ — $ 23.7 (in millions) Columbia Operations NIPSCO Operations Corporate and Other Total Balance as of January 1, 2023 $ 11.1 $ 12.0 $ 0.8 $ 23.9 Current period provisions 28.3 11.5 — 39.8 Write-offs charged against allowance (49.2) (12.4) — (61.6) Recoveries of amounts previously written off 20.0 0.8 — 20.8 Balance as of December 31, 2023 $ 10.2 $ 11.9 $ 0.8 $ 22.9

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2024
Variable Interest Entities [Abstract]
Variable Interest Entities Assets and Liabilities	Our Consolidated Balance Sheets included the following assets and liabilities associated with VIEs. (in millions) December 31, December 31, Net Property, Plant and Equipment $ 1,323.8 $ 1,369.8 Current assets 65.0 63.6 Total assets (1)(2) 1,388.8 1,433.4 Current liabilities 53.7 68.3 Asset retirement obligations 58.3 55.7 Finance lease obligations 40.4 — Total liabilities (1)(2) $ 152.4 $ 124.0 (1) The assets of each VIE represent assets of a consolidated VIE that can be used only to settle obligations of the respective consolidated VIE. The creditors of the liabilities of the VIEs do not have recourse to the general credit of the primary beneficiary. (2)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table presents the calculation of our basic and diluted EPS: Year Ended December 31, (in millions, except per share amounts) 2024 2023 2022 Numerator: Net Income Available to Common Shareholders $ 739.7 $ 661.7 $ 749.0 Less: Income allocated to participating securities 1.6 0.6 — Net Income Available to Common Shareholders - Basic $ 738.1 $ 661.1 $ 749.0 Add: Dilutive effect of Equity Units — 1.4 2.0 Net Income Available to Common Shareholders - Diluted $ 738.1 $ 662.5 $ 751.0 Denominator: Average common shares outstanding - Basic 454.2 416.1 407.1 Dilutive potential common shares: Equity Units purchase contracts — 29.8 30.2 Equity Units purchase contract payment balance — 0.9 3.2 Shares contingently issuable under employee stock plans 0.9 0.7 0.9 Shares restricted under employee stock plans 0.3 0.4 0.5 ATM Forward agreements 0.6 — 0.8 Average Common Shares - Diluted 456.0 447.9 442.7 Earnings per common share: Basic $ 1.63 $ 1.59 $ 1.84 Diluted $ 1.62 $ 1.48 $ 1.70

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2024
Equity [Abstract]
Schedule of Stock by Class - Preferred	Equity Units. On December 1, 2023, we issued 33,898,837 shares of our common stock under the purchase contract component of the Corporate Units. As of December 1, 2023, each holder of Corporate Units was deemed to have automatically delivered to us the related Series C Mandatory Convertible Preferred Stock that were components of the Corporate Units in full satisfaction of such holder’s obligations under the related purchase contract, and all 862,500 shares of Series C Mandatory Convertible Preferred Stock were returned to the status of authorized but unissued preferred stock, par value of $0.01 per share, without designation as to series. We voluntarily delisted the Corporate Units from the New York Stock Exchange on December 1, 2023. Refer to Note 5, "Earnings Per Share," for additional information regarding our treatment of the Equity Units for diluted EPS. On October 21, 2024, we filed a Certificate of Elimination to our Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to eliminate from the Amended and Restated Certificate of Incorporation all matters set forth in the Certificate of Designations with respect to the Series C Mandatory Convertible Preferred Stock.

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2024
Long-Term Debt, Current and Noncurrent [Abstract]
Schedule of Long-Term Debt	Our long-term debt as of December 31, 2024 and 2023 is as follows: Long-term debt type Maturity as of December 31, 2024 Weighted average interest rate (%) Outstanding balance as of December 31, (in millions) 2024 2023 Senior notes: NiSource August 2025 0.950 % $ 1,250.0 $ 1,250.0 NiSource May 2027 3.490 % 1,000.0 1,000.0 NiSource December 2027 6.780 % 3.0 3.0 NiSource March 2028 5.250 % 1,050.0 1,050.0 NiSource July 2029 5.200 % 600.0 — NiSource September 2029 2.950 % 750.0 750.0 NiSource May 2030 3.600 % 1,000.0 1,000.0 NiSource February 2031 1.700 % 750.0 750.0 NiSource June 2033 5.400 % 450.0 450.0 NiSource April 2034 5.350 % 650.0 — NiSource December 2040 6.250 % 152.6 152.6 NiSource June 2041 5.950 % 347.4 347.4 NiSource February 2042 5.800 % 250.0 250.0 NiSource February 2043 5.250 % 500.0 500.0 NiSource February 2044 4.800 % 750.0 750.0 NiSource February 2045 5.650 % 500.0 500.0 NiSource May 2047 4.375 % 1,000.0 1,000.0 NiSource March 2048 3.950 % 750.0 750.0 NiSource June 2052 5.000 % 350.0 350.0 Total senior notes $ 12,103.0 $ 10,853.0 Junior subordinated notes: NiSource November 2054 6.950 % 500.0 — NiSource March 2055 6.375 % 500.0 — Total junior subordinated notes $ 1,000.0 $ — Medium term notes: NiSource May 2027 7.990 % $ 29.0 $ 29.0 NIPSCO June 2027 to August 2027 7.644 % 58.0 58.0 Columbia of Massachusetts December 2025 to February 2028 6.373 % 15.0 15.0 Total medium term notes $ 102.0 $ 102.0 Finance leases: NiSource Corporate Services January 2025 to September 2027 3.470 % $ 14.6 $ 30.5 NIPSCO December 2027 to November 2035 5.250 % 124.3 61.2 Columbia of Ohio December 2025 to March 2044 6.150 % 85.6 90.3 Columbia of Virginia July 2029 to November 2039 6.190 % 15.2 16.1 Columbia of Kentucky May 2027 5.360 % 0.1 0.2 Columbia of Pennsylvania July 2027 to May 2035 4.470 % 6.4 7.1 Total finance leases $ 246.2 $ 205.4 Less: Unamortized issuance costs and discounts (95.5) (81.1) Less: Current portion of long term debt (1,281.2) (23.8) Total Long-Term Debt $ 12,074.5 $ 11,055.5

Property, Plant And Equipment (

Property, Plant And Equipment (Tables)	12 Months Ended
	Dec. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule Of Property, Plant And Equipment	Our property, plant and equipment on the Consolidated Balance Sheets are classified as follows: At December 31, (in millions) 2024 2023 Property, Plant and Equipment Gas Distribution Utility $ 20,007.2 $ 18,154.5 Electric Utility 8,666.8 7,907.9 Corporate 248.1 274.2 Construction Work in Process 2,084.7 1,261.1 JV Renewable Generation Assets (1) 1,434.2 1,434.4 Non-Utility and Other 1,711.9 1,450.0 Total Property, Plant and Equipment $ 34,152.9 $ 30,482.1 Accumulated Depreciation and Amortization Gas Distribution Utility $ (4,166.8) $ (3,924.4) Electric Utility (2,707.8) (2,709.5) Corporate (163.4) (174.2) JV Renewable Generation Assets (1) (110.4) (64.5) Non-Utility and Other (1,550.6) (1,334.6) Total Accumulated Depreciation and Amortization $ (8,699.0) $ (8,207.2) Net Property, Plant and Equipment $ 25,453.9 $ 22,274.9 (1) These JV renewable generation assets owned and operated by JVs between NIPSCO and unrelated tax equity partners represent Non-Utility Property, are depreciated straight-line over 30 years and are part of our NIPSCO Operations segment. Refer to Note 4, "Noncontrolling Interests," for additional information.
Schedule Of Depreciation Provisions For Utility Plant As A Percentage Of The Original Cost	The weighted average depreciation provisions for utility plant, as a percentage of the original cost, for the periods ended December 31, 2024, 2023 and 2022 were as follows: 2024 2023 2022 NIPSCO Operations 3.0 % 3.0 % 2.7 % Columbia Operations 2.6 % 2.5 % 2.4 %

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2024
Asset Retirement Obligation [Abstract]
Changes In Liability For Asset Retirement Obligations	Changes in our liability for asset retirement obligations for the years 2024 and 2023 are presented in the table below: (in millions) 2024 2023 Beginning Balance $ 553.0 $ 513.5 Accretion recorded as a regulatory asset/liability 25.3 20.0 Additions 189.9 23.5 Settlements (72.5) (41.6) Change in estimated cash flows 87.5 37.6 Ending Balance $ 783.2 $ 553.0

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2024
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets	Regulatory assets were comprised of the following items: At December 31, (in millions) 2024 2023 Regulatory Assets Unrecognized pension and other postretirement benefit costs (see Note 16) $ 485.3 $ 561.6 Deferred pension and other postretirement benefit costs (see Note 16) 45.3 59.7 Environmental costs (see Note 19-D.) 42.8 40.6 Regulatory effects of accounting for income taxes (see Note 1-N. and Note 15) 172.0 163.5 Under-recovered gas and fuel costs (see Note 1-J.) 82.3 12.7 Depreciation 214.9 201.9 Post-in-service carrying charges 280.8 269.9 Safety activity costs 203.7 206.6 DSM programs 17.8 25.0 Retired coal generating stations 617.0 682.0 Losses on commodity price risk programs (See Note 13) 6.5 24.4 Deferred property taxes 75.9 72.3 Renewable energy investments 81.3 60.8 WAM system filing 21.5 — Customer assistance programs 24.4 — Other 105.8 79.2 Total Regulatory Assets $ 2,477.3 $ 2,460.2 Less: Current Portion 319.9 214.3 Total Noncurrent Regulatory Assets $ 2,157.4 $ 2,245.9
Regulatory Liabilities	Regulatory liabilities were comprised of the following items: At December 31, (in millions) 2024 2023 Regulatory Liabilities Over-recovered gas and fuel costs (see Note 1-J.) $ 21.4 $ 144.5 Cost of removal (see Note 11) 482.8 597.2 Regulatory effects of accounting for income taxes (see Note 1-N. and Note 15) 827.0 849.9 Deferred pension and other postretirement benefit costs (see Note 16) 40.4 54.0 Gains on commodity price risk programs (See Note 13) 28.7 23.3 Customer assistance programs 9.4 19.8 Off-system sales sharing 21.4 19.0 Renewable energy investments (See Note 1-S. and Note 4) 77.0 18.1 Rate refunds 16.6 16.1 Other 57.0 47.4 Total Regulatory Liabilities $ 1,581.7 $ 1,789.3 Less: Current Portion 150.5 278.6 Total Noncurrent Regulatory Liabilities $ 1,431.2 $ 1,510.7

Risk Management Activities (Tab

Risk Management Activities (Tables)	12 Months Ended
	Dec. 31, 2024
Risk Management Activities [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Risk management assets and liabilities on our derivatives are presented on the Consolidated Balance Sheets as shown below: December 31, 2024 December 31, 2023 (in millions) Assets Liabilities Assets Liabilities Current (1) Derivatives not designated as hedging instruments $ 9.1 $ 2.3 $ 1.1 $ 7.5 Total $ 9.1 $ 2.3 $ 1.1 $ 7.5 Noncurrent (2) Derivatives not designated as hedging instruments $ 17.9 $ 1.2 $ 22.2 $ 1.9 Total $ 17.9 $ 1.2 $ 22.2 $ 1.9 (1) Current assets and liabilities are presented in "Prepayments and other" and "Other accruals", respectively, on the Consolidated Balance Sheets. (2) Noncurrent assets and liabilities are presented in "Deferred charges and other" and "Other noncurrent liabilities and deferred credits", respectively, on the Consolidated Balance Sheets.

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables present financial assets and liabilities measured and recorded at fair value on our Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of December 31, 2024 and December 31, 2023: Recurring Fair Value Measurements December 31, 2024 ( in millions ) Quoted Prices Significant Other Significant Balance as of December 31, 2024 Assets U.S. Treasury debt securities (1) $ 80.1 $ — $ — $ 80.1 Risk management assets — 27.0 — 27.0 Available-for-sale debt securities — 86.7 — 86.7 Total $ 80.1 $ 113.7 $ — $ 193.8 Liabilities Risk management liabilities $ — $ 3.5 $ — $ 3.5 Total $ — $ 3.5 $ — $ 3.5 (1) Treasury bills are presented in "Cash and cash equivalents" and "Restricted cash" on the Consolidated Balance Sheets. Recurring Fair Value Measurements December 31, 2023 ( in millions ) Quoted Prices Significant Other Significant Balance as of December 31, 2023 Assets Risk management assets $ — $ 23.3 $ — $ 23.3 Available-for-sale debt securities — 159.1 — 159.1 Total $ — $ 182.4 $ — $ 182.4 Liabilities Risk management liabilities $ — $ 9.4 $ — $ 9.4 Total $ — $ 9.4 $ — $ 9.4
Debt Securities, Available-for-sale	The amortized cost, gross unrealized gains and losses, allowance for credit losses, and fair value of available-for-sale securities at December 31, 2024 and 2023 were: December 31, 2024 (in millions) Amortized Gross Gross Unrealized Losses (1) Allowance for Credit Losses Fair Value Available-for-sale debt securities Corporate/Other debt securities $ 91.9 $ 0.5 $ (5.6) $ (0.1) $ 86.7 Total $ 91.9 $ 0.5 $ (5.6) $ (0.1) $ 86.7 December 31, 2023 (in millions) Amortized Gross Gross Unrealized Losses (2) Allowance for Credit Losses Fair Value Available-for-sale debt securities U.S. Treasury debt securities $ 63.8 $ — $ (3.2) $ — $ 60.6 Corporate/Other debt securities 105.2 0.8 (6.9) (0.6) 98.5 Total $ 169.0 $ 0.8 $ (10.1) $ (0.6) $ 159.1 (1) Fair value of Corporate/Other debt securities in an unrealized loss position without an allowance for credit losses is $70.1 million at December 31, 2024. (2) Fair value of U.S. Treasury debt securities and Corporate/Other debt securities in an unrealized loss position without an allowance for credit losses is $58.7 million and $74.8 million, respectively, at December 31, 2023.
Carrying Amount And Estimated Fair Values Of Financial Instruments	The carrying amount and estimated fair values of these financial instruments were as follows: At December 31, (in millions) Carrying Amount 2024 Estimated Fair Value 2024 Carrying Amount 2023 Estimated Fair Value 2023 Long-term debt (including current portion) $ 13,355.7 $ 12,505.2 $ 11,079.3 $ 10,370.9

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Schedule Of Components Of Income Tax Expense	The components of income tax expense (benefit) were as follows: Year Ended December 31, (in millions) 2024 2023 2022 Income Taxes Current Federal $ (19.3) $ — $ 0.4 State 9.4 5.3 7.3 Total Current (Benefit) Expense (9.9) 5.3 7.7 Deferred Federal Taxes before operating loss carryforwards and investment credits 105.9 49.7 87.9 Tax utilization expense of operating loss carryforwards 60.4 65.1 93.1 Investment tax credits (0.1) (2.1) — State 2.6 22.5 (23.0) Total Deferred Expense 168.8 135.2 158.0 Deferred Investment Tax Credits (0.8) (1.0) (1.1) Income Taxes from Continuing Operations $ 158.1 $ 139.5 $ 164.6 In connection with the NIPSCO Minority Interest Transaction during 2023, NiSource recognized a $63.5 million income tax benefit in additional paid in capital related to 19.9% of NIPSCO’s excess deferred income taxes attributable to Blackstone’s noncontrolling interest. This benefit does not impact NIPSCO’s regulatory books or the excess deferred taxes that will benefit customers through lower future rates in accordance with applicable regulatory orders. See Note 4, "Noncontrolling Interests," for further discussion of the NIPSCO Minority Interest Transaction.
Schedule Of Reasons Behind Differences In Computation Of Total Income Taxes	The following table represents a reconciliation of income tax expense at the statutory federal income tax rate to the actual income tax expense from continuing operations: Year Ended December 31, (in millions) 2024 2023 2022 Book income before income taxes $ 1,002.8 $ 813.9 $ 956.4 Tax expense at statutory federal income tax rate 210.6 21.0 % 170.8 21.0 % 200.8 21.0 % Increases (reductions) in taxes resulting from: State income taxes, net of federal income tax benefit 11.7 1.2 13.7 1.7 4.5 0.5 Amortization of regulatory liabilities (11.1) (1.1) (38.2) (4.7) (38.5) (4.0) Employee stock ownership plan dividends and other compensation (1.3) (0.1) (1.3) (0.2) (1.2) (0.1) Federal tax credits (23.3) (2.3) (4.9) (0.6) (2.3) (0.2) Tax effect of non-controlling Interest (27.3) (2.7) — — — — Other adjustments (1.2) (0.2) (0.6) (0.1) 1.3 — Income Taxes $ 158.1 15.8 % $ 139.5 17.1 % $ 164.6 17.2 %
Schedule Of Principal Components Of Net Deferred Tax Liability	Deferred income taxes result from temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. The principal components of our net deferred tax liabilities were as follows: At December 31, (in millions) 2024 2023 Deferred tax liabilities Accelerated depreciation and other property differences $ 1,419.4 $ 1,384.8 Partnership basis differences 1,328.6 1,241.9 Other regulatory assets 210.1 212.1 Total Deferred Tax Liabilities 2,958.1 2,838.8 Deferred tax assets Other regulatory liabilities and deferred investment tax credits (including TCJA) 170.4 182.2 Pension and other postretirement/postemployment benefits 58.8 58.6 Loss and credit carryforwards 369.4 422.9 Environmental liabilities 12.2 10.1 Other accrued liabilities 43.4 40.3 Other, net 28.7 50.7 Total Deferred Tax Assets 682.9 764.8 Valuation Allowance (6.4) (6.4) Net Deferred Tax Assets 676.5 758.4 Net Deferred Tax Liabilities $ 2,281.6 $ 2,080.4
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows: At December 31, 2024 (in millions) 2024 2023 2022 Opening Balance $ 21.7 $ 21.7 $ 21.7 Gross decreases - tax positions in prior period — — — Gross increases - current period tax positions — — — Ending Balance $ 21.7 $ 21.7 $ 21.7 Offset for net operating loss carryforwards (21.7) (21.7) (21.7) Balance, Less Net Operating Loss Carryforwards $ — $ — $ —
Summary of Tax Credit Carryforwards	At December 31, 2024 (in millions) Deductible Amount Deferred Tax Asset Valuation Allowance Expiration Period Federal losses $ 1,369.1 $ 287.5 $ — 2037 Federal investment tax credits — 2.2 — 2043 Federal production tax credits — 1.0 — 2040-2043 Federal other credit — 17.3 — 2029-2043 State losses 2,024.4 81.9 (6.4) 2031-2037 Total $ 389.9 $ (6.4)

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Allocation of Plan Assets	December 31, 2024 Defined Benefit Pension Plan Postretirement Benefit Plan Asset Category Minimum Maximum Minimum Maximum Domestic Equities 10% 30% 0% 55% International Equities 5% 15% 0% 25% Fixed Income 65% 75% 20% 100% Real Estate 0% 0% 0% 0% Private Equity 0% 3% 0% 0% Short-Term Investments 0% 10% 0% 10% December 31, 2023 Defined Benefit Pension Plan Postretirement Benefit Plan Asset Category Minimum Maximum Minimum Maximum Domestic Equities 10% 30% 0% 55% International Equities 5% 15% 0% 25% Fixed Income 65% 75% 20% 100% Real Estate 0% 0% 0% 0% Private Equity 0% 3% 0% 0% Short-Term Investments 0% 10% 0% 10% The actual Pension Plan and Postretirement Plan Asset Mix at December 31, 2024 and December 31, 2023 are as follows: Defined Benefit Pension Assets (1) December 31, Postretirement December 31, Asset Class (in millions) Asset Value % of Total Assets Asset Value % of Total Assets Domestic Equities $ 258.9 19.4 % $ 99.6 40.9 % International Equities 122.5 9.2 % 40.7 16.7 % Fixed Income 891.2 66.7 % 96.5 39.6 % Real Estate 4.0 0.3 % — — Cash/Other 59.8 4.4 % 6.7 2.8 % Total $ 1,336.4 100.0 % $ 243.5 100.0 % (1) Total includes accrued dividends and pending trades with brokers. Defined Benefit Pension Assets (1) December 31, Postretirement Benefit Plan Assets (1) December 31, Asset Class (in millions) Asset Value % of Total Assets Asset Value % of Total Assets Domestic Equities $ 261.7 18.3 % $ 93.7 39.6 % International Equities 141.9 9.9 % 40.7 17.2 % Fixed Income 939.9 65.9 % 97.0 41.0 % Real Estate 4.0 0.3 % — — Cash/Other 79.3 5.6 % 5.1 2.2 % Total $ 1,426.8 100.0 % $ 236.5 100.0 % (1) Total includes accrued dividends and pending trades with brokers.
Schedule Of Fair Value and Changes In The Fair Value Of The Plan Assets	Fair Value Measurements at December 31, 2024: (in millions) December 31, Quoted Prices in Active Markets for Significant Other Significant Pension plan assets: Cash $ 1.2 $ 1.1 $ 0.1 $ — Fixed income securities Government 186.8 — 186.8 — Corporate 486.6 — 486.6 — Mortgages/ Asset Backed Securities 3.6 — 3.6 — Mutual Funds U.S. multi-strategy 56.1 56.1 — — International equities 57.2 57.2 — — Private equity limited partnerships (1) U.S. multi-strategy (2) 3.1 — — — International multi-strategy (3) 0.8 — — — Distressed opportunities 0.1 — — — Real estate (1) 4.0 — — — Commingled funds (1) Short-term money markets 45.9 — — — U.S. equities 202.8 — — — International equities 65.3 — — — Fixed income 214.1 — — — Pension plan assets subtotal $ 1,327.6 $ 114.4 $ 677.1 $ — Other postretirement benefit plan assets: Mutual funds U.S. multi-strategy 87.4 87.4 — — International equities 16.5 16.5 — — Fixed income 96.5 96.5 — — Commingled funds (1) Short-term money markets 6.7 — — — U.S. equities 12.2 — — — International equities 24.2 — — — Other postretirement benefit plan assets subtotal $ 243.5 $ 200.4 $ — $ — Due to brokers, net (4) (0.1) — (0.1) — Accrued income/dividends 8.9 8.9 — Total pension and other postretirement benefit plan assets $ 1,579.9 $ 323.7 $ 677.0 $ — (1)) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. (2) This class includes limited partnerships that invest in a diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily inside the United States. (3) This class includes limited partnerships that invest a in diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily outside the United States. (4) This class represents pending trades with brokers. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2024: (in millions) Fair Value Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 52.6 Daily 1 day U.S. equities 215.0 Daily 1 day - 5 days International equities 89.5 Monthly 10 days-30 days Fixed income 214.1 Daily 3 days Private Equity and Real Estate Limited Partnerships (1) 8.0 N/A N/A Total $ 579.2 (1) Private equity and real estate limited partnerships typically call capital over a 3-5 year period and pay out distributions as the underlying investments are liquidated. The typical expected life of these limited partnerships is 0-15 years, and these investments typically cannot be redeemed prior to liquidation. Fair Value Measurements at December 31, 2023: (in millions) December 31, Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Significant Pension plan assets: Cash $ 2.2 $ 2.0 $ 0.2 $ — Equity securities International equities 1.1 1.1 — — Fixed income securities Government 213.1 — 213.1 — Corporate 482.2 — 482.2 — Mortgages/Asset backed securities 2.4 — 2.4 — Mutual Funds U.S. multi-strategy 113.1 113.1 — — International equities 38.5 38.5 — — Private equity limited partnerships (1) U.S. multi-strategy (2) 4.8 — — — International multi-strategy (3) 1.2 — — — Distressed opportunities 0.1 — — — Real estate (1) 4.0 — — — Commingled funds (1) Short-term money markets 65.3 — — — U.S. equities 148.5 — — — International equities 102.3 — — — Fixed income 242.2 — — — Pension plan assets subtotal $ 1,421.0 $ 154.7 $ 697.9 $ — Other postretirement benefit plan assets: Mutual funds U.S. multi-strategy 82.4 82.4 — — International equities 18.0 18.0 — — Fixed income 97.0 97.0 — — Commingled funds (1) Short-term money markets 5.2 — — — U.S. equities 11.4 — — — International equities 22.8 — — — Other postretirement benefit plan assets subtotal $ 236.8 $ 197.4 $ — $ — Due to brokers, net (4) (2.7) — (2.7) — Accrued income/dividends 8.5 8.5 — — Total pension and other postretirement benefit plan assets $ 1,663.6 $ 360.6 $ 695.2 $ — (1) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. (2) This class includes limited partnerships/fund of funds that invest in a diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily inside the United States. (3) This class includes limited partnerships/fund of funds that invest in diverse portfolio of private equity strategies, including buy-outs, growth capital, special situations and secondary markets, primarily outside the United States. (4) This class represents pending trades with brokers. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2023: (in millions) Fair Value Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 70.5 Daily 1 day U.S. equities 159.9 Daily 1 day -5 days International equities 125.1 Monthly 10 days - 30 days Fixed income 242.2 Daily 3 days Private Equity and Real Estate Limited Partnerships (1) 10.1 N/A N/A Total $ 607.8 (1) Private equity and real estate limited partnerships typically call capital over a 3-5 year period and pay out distributions as the underlying investments are liquidated. The typical expected life of these limited partnerships is 0-15 years, and these investments typically cannot be redeemed prior to liquidation.
Schedule Of Reconciliation Of The Plan Funded Status	The following table provides a reconciliation of the plans’ funded status and amounts reflected in our Consolidated Balance Sheets at December 31 based on a December 31 measurement date: Pension Benefits Other Postretirement Benefits (in millions) 2024 2023 2024 2023 Change in projected benefit obligation (1) Benefit obligation at beginning of year $ 1,401.8 $ 1,427.4 $ 468.8 $ 449.0 Service cost 21.9 20.5 5.0 5.1 Interest cost 64.9 68.4 22.0 21.8 Plan participants’ contributions — — 3.6 4.2 Plan amendments — — — 3.4 Actuarial loss (gain) (2) (64.8) 27.4 (22.5) 29.1 Benefits paid (136.4) (141.9) (40.7) (44.3) Estimated benefits paid by incurred subsidy — — 0.1 0.5 Projected benefit obligation at end of year $ 1,287.4 $ 1,401.8 $ 436.3 $ 468.8 Change in plan assets Fair value of plan assets at beginning of year $ 1,426.8 $ 1,422.8 $ 236.5 $ 224.9 Actual return on plan assets 43.7 142.8 20.0 28.2 Employer contributions 2.4 3.1 23.6 23.4 Plan participants’ contributions — — 3.8 4.3 Benefits paid (136.4) (141.9) (40.7) (44.3) Fair value of plan assets at end of year $ 1,336.5 $ 1,426.8 $ 243.2 $ 236.5 Funded Status at end of year $ 49.1 $ 25.0 $ (193.1) $ (232.3) Amounts recognized in the statement of financial position consist of: Noncurrent assets 66.5 44.1 — — Current liabilities (2.3) (2.2) (1.0) (1.0) Noncurrent liabilities (15.1) (16.9) (192.1) (231.3) Net amount recognized at end of year (3) $ 49.1 $ 25.0 $ (193.1) $ (232.3) Amounts recognized in accumulated other comprehensive income or regulatory asset/liability (4) Unrecognized prior service credit $ 0.3 $ 0.3 $ 3.8 $ 2.1 Unrecognized actuarial loss 451.4 500.4 47.0 76.6 Net amount recognized at end of year $ 451.7 $ 500.7 $ 50.8 $ 78.7 (1) The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in accumulated postretirement benefit obligation. (2) The pension actuarial gain was primarily driven by the increase in discount rates interest rate movements. The postretirement benefit actuarial loss (gain) was also primarily driven by a increase in discount rates and claims experience changes in trend rates. (3) We recognize our Consolidated Balance Sheets underfunded and overfunded status of our various defined benefit postretirement plans, measured as the difference between the fair value of the plan assets and the benefit obligation. (4) We determined that for certain rate-regulated subsidiaries the future recovery of pension and other postretirement benefits costs is probable. These rate-regulated subsidiaries recorded regulatory assets and liabilities of $485.3 million and zero, respectively, as of December 31, 2024, and $561.6 million and zero, respectively, as of December 31, 2023 that would otherwise have been recorded to accumulated other comprehensive loss.
Schedule of Benefit Obligations in Excess of Fair Value of Plan Assets	for pension plans with a projected benefit obligation in excess of plan assets: December 31, 2024 2023 Accumulated Benefit Obligation $ 17.4 $ 19.1 Funded Status Projected Benefit Obligation $ 17.4 $ 19.1 Funded Status of Underfunded Pension Plans at End of Year $ (17.4) $ (19.1) The following table sets forth the year end accumulated benefit obligation, projected benefit obligation and fair value of plan assets for pension plans with plan assets in excess of the projected benefit obligation: December 31, 2024 2023 Accumulated Benefit Obligation $ 1,261.0 $ 1,371.8 Funded Status Fair Value of Plan Assets $ 1,336.4 $ 1,426.8 Projected Benefit Obligation 1,269.9 1,382.7 Funded Status of Overfunded Pension Plans at End of Year $ 66.5 $ 44.1
Schedule Of Expected Payments To Participants In Pension Plan	The expected benefits are estimated based on the same assumptions used to measure our benefit obligation at the end of the year and include benefits attributable to the estimated future service of employees: (in millions) Pension Benefits Other Year(s) 2025 $ 142.6 $ 36.6 2026 136.6 36.1 2027 130.9 36.1 2028 125.8 35.8 2029 119.4 35.6 2030-2034 528.6 171.7
Components Of The Plans' Net Periodic Benefits Cost	The following table provides the components of the plans’ actuarially determined net periodic benefits cost for each of the three years ended December 31, 2024, 2023 and 2022: Pension Benefits Other Postretirement (in millions) 2024 2023 2022 2024 2023 2022 Components of Net Periodic Benefit (Income) Cost (1) Service cost $ 21.9 $ 20.5 $ 27.8 $ 5.0 $ 5.1 $ 6.5 Interest cost 64.9 68.4 40.5 22.0 21.8 12.0 Expected return on assets (95.3) (94.5) (90.8) (16.1) (15.1) (16.2) Amortization of prior service cost (credit) 0.1 0.1 0.1 (1.8) (2.1) (2.2) Recognized actuarial loss 28.6 33.7 20.3 3.2 3.3 2.6 Settlement loss 7.2 9.2 12.4 — — — Total Net Periodic Benefits Cost $ 27.4 $ 37.4 $ 10.3 $ 12.3 $ 13.0 $ 2.7 (1) Service cost is presented in "Operation and maintenance" on the Statements of Consolidated Income. Non-service cost components are presented within "Other, net."
Schedule Of Significant Actuarial Assumptions In Determining Funded Status Plan	The following table provides the key assumptions that were used to calculate the pension and other postretirement benefits obligations for our various plans as of December 31: Pension Benefits Other Postretirement Benefits 2024 2023 2024 2023 Weighted-average assumptions to Determine Benefit Obligation Discount Rate 5.58 % 4.95 % 5.66 % 4.98 % Rate of Compensation Increases 4.00 % 4.00 % N/A N/A Interest Crediting Rates 4.00 % 4.00 % N/A N/A Health Care Trend Rates Trend for Next Year N/A N/A 9.77 % 8.84 % Ultimate Trend N/A N/A 4.75 % 4.75 % Year Ultimate Trend Reached N/A N/A 2033 2032 The following table provides the key assumptions that were used to calculate the net periodic benefits cost for our various plans: Pension Benefits Other Postretirement 2024 2023 2022 2024 2023 2022 Weighted-average Assumptions to Determine Net Periodic Benefit Cost Discount rate - service cost 5.06 % 5.25 % 3.08 % 5.14 % 5.30 % 3.21 % Discount rate - interest cost 4.88 % 5.06 % 2.11 % 4.89 % 5.07 % 2.24 % Expected Long-Term Rate of Return on Plan Assets 7.02 % 7.00 % 4.80 % 7.06 % 6.96 % 5.72 % Rate of Compensation Increases 4.00 % 4.00 % 4.00 % N/A N/A N/A Interest Crediting Rates 4.00 % 4.00 % 4.00 % N/A N/A N/A
Schedule Of Changes In Plan Assets And Projected Benefit Obligations Recognized In Other Comprehensive Income	The following table provides other changes in plan assets and projected benefit obligations recognized in other comprehensive income or regulatory asset or liability: Pension Benefits Other Postretirement (in millions) 2024 2023 2024 2023 Other Changes in Plan Assets and Projected Benefit Obligations Net prior service cost $ — $ — $ — $ 3.3 Net actuarial (gain) loss (13.1) (20.9) (26.4) 16.0 Settlements/curtailments (7.2) (9.2) — — Less: amortization of prior service cost (0.1) (0.1) 1.8 2.1 Less: amortization of net actuarial loss (28.6) (33.7) (3.2) (3.3) Total Recognized in Other Comprehensive Income or Regulatory $ (49.0) $ (63.9) $ (27.8) $ 18.1 Amount Recognized in Net Periodic Benefits Cost and Other $ (21.6) $ (26.5) $ (15.5) $ 31.1

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2024
Share-Based Payment Arrangement, Noncash Expense [Abstract]
Performance Award Details	The following table presents details of the performance awards described above. Award Year Service Conditions Lapse date Performance Period Award Conditions Shares outstanding at 12/31/2024 (shares) Grant Date Fair Value (in millions) 2024 2/26/2027 01/01/2024- 12/31/2026 Non-GAAP Financial and Operational Measures 619,673 $ 17.4 Relative Total Shareholder Return 206,524 $ 6.9 2023 2/28/2026 01/01/2023- 12/31/2025 Non-GAAP Financial and Operational Measures 430,670 $ 13.3 Relative Total Shareholder Return 143,540 $ 5.4 2022 2/28/2025 01/01/2022- 12/31/2024 Non-GAAP Financial Measure 195,460 $ 7.4 Relative Total Shareholder Return 195,460 $ 10.6
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Transactions Of Share Based Compensation Other Than Stock Options	(shares) Restricted Stock Weighted Average Non-vested at December 31, 2023 1,066,916 25.71 Granted 655,713 26.10 Forfeited (167,057) 26.19 Vested (227,452) 22.90 Non-vested at December 31, 2024 1,328,120 26.49
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Transactions Of Share Based Compensation Other Than Stock Options	(shares) Performance Weighted Average Non-vested at December 31, 2023 1,558,509 28.01 Granted 896,363 27.05 Forfeited (189,080) 31.75 Vested (546,569) 21.95 Non-vested at December 31, 2024 1,719,223 24.96

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2024
Leases [Abstract]
Lease Cost	Income statement presentation for these costs (when ultimately recognized on the income statement) is also included: Year Ended December 31, (in millions) Income Statement Classification 2024 2023 Finance lease cost Amortization of right-of-use assets Depreciation and amortization $ 27.1 $ 32.0 Interest on lease liabilities Interest expense, net 13.5 8.6 Total finance lease cost 40.6 40.6 Operating lease cost Operation and maintenance 14.7 11.3 Total lease cost $ 55.3 $ 51.9
Right-of-Use Assets and Liabilities	Our right-of-use assets and liabilities are presented in the following lines on the Consolidated Balance Sheets: At December 31, (in millions) Balance Sheet Classification 2024 2023 Assets Finance leases Net Property, Plant and Equipment $ 222.9 $ 184.3 Operating leases Deferred charges and other 26.4 32.9 Total leased assets $ 249.3 217.2 Liabilities Current Finance leases Current portion of long-term debt $ 22.9 23.8 Operating leases Other accruals 9.1 8.3 Noncurrent Finance leases Long-term debt, excluding amounts due within one year 223.3 181.6 Operating leases Other noncurrent liabilities and deferred credits 18.2 25.8 Total lease liabilities $ 273.5 $ 239.5
Lease Information	Other pertinent information related to leases was as follows: Year Ended December 31, (in millions) 2024 2023 Cash paid for amounts included in the measurement of lease liabilities Operating cash flows used for finance leases $ 11.2 $ 9.3 Operating cash flows used for operating leases 14.5 11.1 Financing cash flows used for finance leases 26.9 33.1 Right-of-use assets obtained in exchange for lease obligations Finance leases 65.9 64.5 Operating leases $ 12.2 $ 5.6 December 31, 2024 December 31, 2023 Weighted-average remaining lease term (years) Finance leases 20.5 16.4 Operating leases 5.6 6.7 Weighted-average discount rate Finance leases 5.6 % 5.5 % Operating leases 4.5 % 4.3 %
Lease Maturity	Maturities of our lease liabilities as of December 31, 2024 were as follows: As of December 31, 2024, (in millions) Total Finance Leases Operating Leases 2025 $ 44.6 $ 34.6 $ 10.0 2026 34.7 29.4 5.3 2027 28.5 24.2 4.3 2028 26.1 23.0 3.1 2029 21.5 19.0 2.5 Thereafter 304.9 299.2 5.7 Total lease payments 460.3 429.4 30.9 Less: Imputed interest (186.8) (183.2) (3.6) Total $ 273.5 $ 246.2 $ 27.3 Reported as of December 31, 2024 Short-term lease liabilities 32.0 22.9 9.1 Long-term lease liabilities 241.5 223.3 18.2 Total lease liabilities $ 273.5 $ 246.2 $ 27.3

Other Commitments And Conting_2

Other Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity	Contractual Obligations . We have certain contractual obligations requiring payments at specified periods. The obligations include long-term debt, lease obligations, energy commodity contracts and obligations for various services including pipeline capacity and outsourcing of IT services. The total contractual obligations in existence at December 31, 2024 and their maturities were: (in millions) Total 2025 2026 2027 2028 2029 After Long-term debt (1) $ 13,205.0 $ 1,260.0 $ — $ 1,090.0 $ 1,055.0 $ 1,350.0 $ 8,450.0 Interest payments on long-term debt 8,090.3 566.2 551.1 531.7 481.6 453.9 5,505.8 Finance leases (2) 429.4 34.6 29.4 24.2 23.0 19.0 299.2 Operating leases (3) 30.9 10.0 5.3 4.3 3.1 2.5 5.7 Energy commodity contracts 119.7 118.5 0.3 0.3 0.4 0.2 — Service obligations: Pipeline service obligations 2,694.6 685.5 631.2 609.2 373.2 245.2 150.3 IT service obligations 120.7 73.9 30.3 11.4 5.1 — — Plant equipment purchase obligations 173.5 140.5 24.9 4.3 3.8 — — Other liabilities (4) 336.0 287.0 7.9 7.7 7.6 7.7 18.1 Total contractual obligations $ 25,200.1 $ 3,176.2 $ 1,280.4 $ 2,283.1 $ 1,952.8 $ 2,078.5 $ 14,429.1 (1) Long-term debt balance excludes unamortized issuance costs and discounts of $95.5 million. (2) Finance lease payments shown above are inclusive of interest totaling $183.2 million. (3) Operating lease payments shown above are inclusive of interest totaling $3.6 million. Operating lease balances do not include obligations for possible fleet vehicle lease renewals beyond the initial lease term. While we have the ability to renew these leases beyond the initial term, we are not reasonably certain to do so as they are renewed month-to-month after the first year. (4) Other liabilities shown above are primarily related to the Dunns Bridge II and Indiana Crossroads Solar Developer payments due in 2025 and ongoing maintenance service agreements for our renewable joint ventures.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2024
Components of Accumulated Other Comprehensive Income (Loss) [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table displays the activity of Accumulated Other Comprehensive Loss, net of tax: (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2022 $ 2.1 $ (122.5) $ (6.4) $ (126.8) Other comprehensive (loss) income before reclassifications (13.7) 109.7 (8.9) 87.1 Amounts reclassified from accumulated other comprehensive loss 0.4 0.2 2.0 2.6 Net current-period other comprehensive (loss) income (13.3) 109.9 (6.9) 89.7 Balance as of December 31, 2022 $ (11.2) $ (12.6) $ (13.3) $ (37.1) Other comprehensive (loss) income before reclassifications 3.1 (0.5) (1.4) 1.2 Amounts reclassified from accumulated other comprehensive loss 0.8 0.3 1.2 2.3 Net current-period other comprehensive (loss) income 3.9 (0.2) (0.2) 3.5 Balance as of December 31, 2023 $ (7.3) $ (12.8) $ (13.5) $ (33.6) Other comprehensive income (loss) before reclassifications 1.5 — (1.2) 0.3 Amounts reclassified from accumulated other comprehensive loss 1.8 (0.4) 1.5 2.9 Net current-period other comprehensive income (loss) 3.3 (0.4) 0.3 3.2 Balance as of December 31, 2024 $ (4.0) $ (13.2) $ (13.2) $ (30.4) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Business Segment Information (T

Business Segment Information (Tables)	12 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Schedule Of Operating Income Derived From Revenues And Expenses By Segment	Year Ended December 31, 2024 (in millions) Columbia Operations NIPSCO Operations Total of Reportable Segments Operating Revenues External Revenue $ 2,703.2 $ 2,751.0 $ 5,454.2 Intersegment Revenue 12.8 1.0 13.8 Total Operating Revenue $ 2,716.0 $ 2,752.0 $ 5,468.0 Cost of energy 514.7 617.5 1,132.2 O&M 837.5 761.4 1,598.9 Depreciation 409.1 590.3 999.4 Total other taxes 218.6 64.3 282.9 Other segment items (1) 7.4 (1.3) 6.1 Operating Income $ 728.7 $ 719.8 $ 1,448.5 Capital Expenditures (2) $ 1,209.0 $ 2,252.4 $ 3,461.4 Assets $ 14,769.5 $ 15,823.5 $ 30,593.0 (1) Other segment items consists of Loss (gain) on Sale or Impairment of Assets and other segment income or expenses deemed insignificant which are used to reach our measurement of segment profit or loss, Operating Income. (2) Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures in current liabilities, the capitalized portion of the Corporate Incentive Plan payout, and AFUDC Equity. Year Ended December 31, 2023 (in millions) Columbia Operations NIPSCO Operations Total of Reportable Segments Operating Revenues External Revenue $ 2,733.9 $ 2,770.7 $ 5,504.6 Intersegment Revenue 12.2 0.9 13.1 Total Operating Revenue $ 2,746.1 $ 2,771.6 $ 5,517.7 Cost of energy 645.0 888.3 1,533.3 O&M 792.3 787.7 1,580.0 Depreciation 371.7 493.8 865.5 Total other taxes 198.8 57.9 256.7 Other segment items (1) — 2.2 2.2 Operating Income $ 738.3 $ 541.7 $ 1,280.0 Capital Expenditures (2) $ 1,159.6 $ 1,294.8 $ 2,454.4 Assets $ 13,664.5 $ 13,962.6 $ 27,627.1 (1) Other segment items consists of Loss(gain) on Sale or Impairment of Assets and other segment income or expenses deemed insignificant which are used to reach our measurement of segment profit or loss, Operating Income. (2) Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures in current liabilities, the capitalized portion of the Corporate Incentive Plan payout, and AFUDC Equity. Year Ended December 31, 2022 (in millions) Columbia Operations NIPSCO Operations Total of Reportable Segments Operating Revenues External Revenue $ 2,951.9 $ 2,886.2 $ 5,838.1 Intersegment Revenue 12.5 0.9 13.4 Total Operating Revenue $ 2,964.4 $ 2,887.1 $ 5,851.5 Cost of energy 978.4 1,132.1 2,110.5 O&M 791.3 740.4 1,531.7 Depreciation 329.4 449.4 778.8 Total other taxes 184.2 72.1 256.3 Other segment items (1) (103.9) — (103.9) Operating Income $ 785.0 $ 493.1 $ 1,278.1 Capital Expenditures (2) $ 1,237.9 $ 1,018.9 $ 2,256.8 Assets $ 13,059.4 $ 11,759.9 $ 24,819.3 (1) Other segment items consists of proceeds from a property insurance settlement related to the Greater Lawrence Incident and other segment income or expenses deemed insignificant which are used to reach our measurement of segment profit or loss, Operating Income. (2) Amounts differ from those presented on the Statements of Consolidated Cash Flows primarily due to the inclusion of capital expenditures in current liabilities, the capitalized portion of the Corporate Incentive Plan payout, and AFUDC Equity. To reconcile the segment tables above to consolidated NiSource: Year Ended December 31, 2024 (in millions) Total Reportable Segments Corporate and Other Eliminations Consolidated NiSource Total Operating Revenue $ 5,468.0 $ 581.9 $ (594.8) $ 5,455.1 Operating Income 1,448.5 7.0 — 1,455.5 Capital Expenditures 3,461.4 231.1 — 3,692.5 Assets 30,593.0 1,195.1 — 31,788.1 Year Ended December 31, 2023 (in millions) Total Reportable Segments Corporate and Other Eliminations Consolidated NiSource Total Operating Revenue $ 5,517.7 $ 504.6 $ (516.9) $ 5,505.4 Operating Income 1,280.0 15.5 — 1,295.5 Capital Expenditures 2,454.4 236.3 — 2,690.7 Assets 27,627.1 3,450.1 — 31,077.2 Year Ended December 31, 2022 (in millions) Total Reportable Segments Corporate and Other Eliminations Consolidated NiSource Total Operating Revenue $ 5,851.5 $ 477.5 $ (478.4) $ 5,850.6 Operating Income (Loss) 1,278.1 (12.3) — 1,265.8 Capital Expenditures 2,256.8 41.2 — 2,298.0 Assets 24,819.3 1,917.3 — 26,736.6

Other, Net (Tables)

Other, Net (Tables)	12 Months Ended
	Dec. 31, 2024
Other Nonoperating Income (Expense) [Abstract]
Schedule Of Other, Net	The following table displays the components of Other, Net included on the Statements of Consolidated Income: Year Ended December 31, (in millions) 2024 2023 2022 Interest income $ 10.4 $ 9.0 $ 4.3 AFUDC equity 75.1 25.2 15.1 Charitable contributions (5.4) (1.8) (4.4) Pension and other postretirement non-service cost (1) (13.5) (24.0) 27.6 Interest rate swap settlement gain — — 10.0 Miscellaneous (2.1) (0.4) (0.4) Total Other, net $ 64.5 $ 8.0 $ 52.2 (1) See Note 16, "Pension and Other Postemployment Benefits," for additional information.

Interest Expense, Net (Tables)

Interest Expense, Net (Tables)	12 Months Ended
	Dec. 31, 2024
Interest Expense, Operating and Nonoperating [Abstract]
Schedule Of Interest Expense, Net	Year Ended December 31, (in millions) 2024 2023 2022 Interest on long-term debt $ 506.2 $ 404.1 $ 344.5 Interest on short-term borrowings 43.2 108.9 22.7 Debt discount/cost amortization 13.8 13.5 11.7 Accounts receivable securitization fees 1.5 2.7 2.5 Allowance for borrowed funds used and interest capitalized during construction (40.1) (25.3) (6.7) Debt-based post-in-service carrying charges (26.4) (30.7) (21.1) Other 19.0 16.4 8.0 Total Interest Expense, net $ 517.2 $ 489.6 $ 361.6

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2024
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	The following table provides additional information regarding our Consolidated Statements of Cash Flows for the years ended December 31, 2024, 2023 and 2022: Year Ended December 31, (in millions) 2024 2023 2022 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities $ 367.0 $ 315.0 $ 275.1 Assets acquired under a finance lease 65.9 64.5 19.3 Assets acquired under an operating lease 12.2 5.6 8.8 Assets recorded for asset retirement obligations (1) 277.4 61.1 6.3 Purchase contract liability, net of fees and payments (2) — — 65.0 Schedule of interest and income taxes paid: Cash paid for interest on debt, net of interest capitalized amounts $ 468.2 $ 433.9 $ 343.8 Cash paid for interest on finance leases 11.2 8.6 8.5 Cash paid for income taxes, net of refunds 4.3 9.4 7.2 (1) See Note 11, "Asset Retirement Obligations," for additional information. (2) Refer to Note 6, "Equity," for additional information.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2024
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule of Valuation and Qualifying Accounts Disclosure	NISOURCE INC. SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS Twelve months ended December 31, 2024 Additions ($ in millions) Balance Jan. 1, 2024 Charged to Costs and Expenses Charged to Other Account (1) Deductions for Purposes for which Reserves were Created Balance Dec. 31, 2024 Reserves Deducted in Consolidated Balance Sheet from Assets to Which They Apply: Reserve for accounts receivable $ 22.9 $ 23.2 $ 32.3 $ 54.7 $ 23.7 Reserve for deferred charges and other 1.3 — (0.2) — 1.1 Twelve months ended December 31, 2023 Additions ($ in millions) Balance Jan. 1, 2023 Charged to Costs and Expenses Charged to Other Account (1) Deductions for Purposes for which Reserves were Created Balance Dec. 31, 2023 Reserves Deducted in Consolidated Balance Sheet from Assets to Which They Apply: Reserve for accounts receivable $ 23.9 $ 23.4 $ 36.6 $ 61.0 $ 22.9 Reserve for deferred charges and other 1.0 — 0.3 — 1.3 Twelve months ended December 31, 2022 Additions ($ in millions) Balance Charged to Costs and Expenses Charged to Other Account (1) Deductions for Purposes for which Reserves were Created Balance Reserves Deducted in Consolidated Balance Sheet from Assets to Which They Apply: Reserve for accounts receivable $ 23.5 $ 20.6 $ 36.4 $ 56.6 $ 23.9 Reserve for deferred charges and other 2.3 — (1.3) — 1.0 (1) Charged to Other Accounts reflects the deferral of bad debt expense to a regulatory asset or the movement of the reserve between short term and long term.

Nature of Operations And Summ_3

Nature of Operations And Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022	Jun. 17, 2023 Rate
Basis Of Accounting Presentation [Line Items]
Number of customers	3,800,000
Pre-tax rate for allowance for funds used during construction	4.80%	3.90%	3.40%
Inventory valued using LIFO	$ 43.8	$ 43.9
Excess of replacement over LIFO value	(12.8)	(22.5)
Inventory valued using the weighted average cost methodology	$ 135.8	$ 222
NIPSCO Holdings II
Basis Of Accounting Presentation [Line Items]
Subsidiary, Ownership Percentage, Parent | Rate				19.90%

Revenue Recognition (Disaggrega

Revenue Recognition (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Customer revenues	$ 5,282.9	$ 5,282.9	$ 5,347.8	$ 5,738.6
Other revenues	172.2	172.2	157.6	112
Total Operating Revenues	5,455.1	5,455.1	5,505.4	5,850.6
NiSource Electric Generation and Power Delivery
Disaggregation of Revenue [Line Items]
Customer revenues	1,829.5		1,701	1,735.5
NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		3,453.4	3,646.8	4,003.1
Electric Operations
Disaggregation of Revenue [Line Items]
Total Operating Revenues			2,770.7	2,886.2
Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Other revenues		0.9	0.8	12.5
Total Operating Revenues		0.9	0.8	12.5
NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		2,654.5	2,686.8	2,790.4
Other revenues		96.5	83.9	95.8
Total Operating Revenues	2,751
NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		1,829.5	1,701	1,735.5
NIPSCO Operations | NIPSCO Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		825	985.8	1,054.9
Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		2,628.4	2,661	2,948.2
Other revenues		74.8	72.9	3.7
Total Operating Revenues		2,703.2	2,733.9	2,951.9
Residential | NiSource Electric Generation and Power Delivery
Disaggregation of Revenue [Line Items]
Customer revenues	649.9		583.9	592.4
Residential | NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		2,365.2	2,462.5	2,609.7
Residential | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues			635	691.5
Residential | Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Residential | NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		531.4
Residential | NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		649.9	583.9	592.4
Residential | Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		1,833.8	1,827.5	1,918.2
Commercial | NiSource Electric Generation and Power Delivery
Disaggregation of Revenue [Line Items]
Customer revenues	620.4		578.1	571
Commercial | NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		779.5	847.9	939.6
Commercial | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues			249	267.4
Commercial | Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Commercial | NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		199.2
Commercial | NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		620.4	578.1	571
Commercial | Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		580.3	598.9	672.2
Industrial | NiSource Electric Generation and Power Delivery
Disaggregation of Revenue [Line Items]
Customer revenues	499.1		474.1	560.6
Industrial | NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		223.2	226	220.6
Industrial | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues			87	85.1
Industrial | Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Industrial | NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		79
Industrial | NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		499.1	474.1	560.6
Industrial | Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		144.2	139	135.5
Off-system | NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		42.6	60.6	192.9
Off-system | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues			0	0
Off-system | Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Off-system | NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		0
Off-system | Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		42.6	60.6	192.9
Miscellaneous | NiSource Electric Generation and Power Delivery
Disaggregation of Revenue [Line Items]
Customer revenues	13.7		21.4	(14.1)
Miscellaneous | NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		41.7	48.2	38.2
Miscellaneous | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues			14.8	10.9
Miscellaneous | Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Miscellaneous | NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		15.4
Miscellaneous | NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		13.7	21.4	(14.1)
Miscellaneous | Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		26.3	33.4	27.3
Wholesale | NiSource Electric Generation and Power Delivery
Disaggregation of Revenue [Line Items]
Customer revenues	38.3		32	13.5
Wholesale | NiSource Gas Distribution
Disaggregation of Revenue [Line Items]
Customer revenues		1.2	1.6	2.1
Wholesale | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues			0	0
Wholesale | Corporate Segment and Other Operating Segment
Disaggregation of Revenue [Line Items]
Customer revenues		0	0	0
Wholesale | NIPSCO Operations
Disaggregation of Revenue [Line Items]
Customer revenues		0
Wholesale | NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		38.3	32	13.5
Wholesale | Columbia Operations
Disaggregation of Revenue [Line Items]
Customer revenues		1.2	1.6	2.1
Public Authority
Disaggregation of Revenue [Line Items]
Customer revenues	$ 8.1		11.5	12.1
Public Authority | NIPSCO Operations | NIPSCO Electric Generation
Disaggregation of Revenue [Line Items]
Customer revenues		$ 8.1	$ 11.5	$ 12.1

Revenue Recognition (Customer A

Revenue Recognition (Customer Accounts Receivable) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Revenue Recognition [Abstract]
Customer Accounts Receivable, Billed (Less Reserve)	$ 525.1	$ 479.4
Customer Accounts Receivable, Unbilled (Less Reserve)	$ 408.1	$ 337.6

Revenue Recognition (Allowance

Revenue Recognition (Allowance for Credit Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	$ 23.7	$ 22.9	$ 23.9
Current period provisions	38.8	39.8
Write-offs charged against allowance	(55.7)	(61.6)
Recoveries of amounts previously written off	17.7	20.8
Electric Operations
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	13.9	11.9	12
Current period provisions	12.1	11.5
Write-offs charged against allowance	(11)	(12.4)
Recoveries of amounts previously written off	0.9	0.8
Corporate Segment and Other Operating Segment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	0	0.8	0.8
Current period provisions	0	0
Write-offs charged against allowance	(0.8)	0
Recoveries of amounts previously written off	0	0
Columbia Operations
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	9.8	10.2	$ 11.1
Current period provisions	26.7	28.3
Write-offs charged against allowance	(43.9)	(49.2)
Recoveries of amounts previously written off	$ 16.8	$ 20

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details)				12 Months Ended
	Sep. 18, 2024 USD ($)	May 24, 2024 USD ($)	Mar. 18, 2024 USD ($)	Dec. 31, 2024 USD ($) Rate MW	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 17, 2023 Rate
Variable Interest Entity [Line Items]
Wind Power Purchase Agreement, Purchase Percentage | Rate				100%
Milestone and final payments to renewable generation asset developer				$ 482,000,000	$ 761,400,000	$ 323,900,000
Income Taxes				158,100,000	139,500,000	$ 164,600,000
Payments to Acquire Assets, Investing Activities	$ 153,300,000	$ 114,900,000	$ 110,600,000
Business Acquisition, Transaction Costs					54,700,000
Proceeds from Contributed Capital					2,160,000,000
Redeemable Noncontrolling Interest, Equity, Other, Carrying Amount					1,360,000,000
Proceeds from (Payments to) Noncontrolling Interests				$ 50,300,000	2,170,700,000
NIPSCO Holdings II
Variable Interest Entity [Line Items]
Subsidiary, Ownership Percentage, Parent | Rate							19.90%
NiSource
Variable Interest Entity [Line Items]
Subsidiary, Ownership Percentage, Parent				80.10%
Rosewater
Variable Interest Entity [Line Items]
Nameplate Capacity | MW				102
Indiana Crossroads Wind
Variable Interest Entity [Line Items]
Nameplate Capacity | MW				302
Indiana Crossroads Solar
Variable Interest Entity [Line Items]
Nameplate Capacity | MW				200
Dunns Bridge I
Variable Interest Entity [Line Items]
Nameplate Capacity | MW				265
Consolidated Variable Interest Entities
Variable Interest Entity [Line Items]
Income Taxes					$ 63,500,000

Variable Interest Entities (Sch

Variable Interest Entities (Schedule of Noncontrolling Interest) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Redeemable Noncontrolling Interest [Line Items]
Noncontrolling interest in consolidated subsidiaries	$ 1,984.1	$ 1,866.7

Variable Interest Entities (S_2

Variable Interest Entities (Schedule of Net Income Attributable to Noncontrolling Interest) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Attributable to noncontrolling [Line Items]
Net income (loss) attributable to noncontrolling interest	$ 84.3	$ (39.9)	$ (12.3)

Variable Interest Entities (S_3

Variable Interest Entities (Schedule of VIE Assets and Liabilities) (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
VIE Assets and Liabilities [Abstract]
Net Property, Plant and Equipment		$ 25,453.9	$ 22,274.9
Current assets	[1]	2,080.2	4,499.4
Total Assets		31,788.1	31,077.2	$ 26,736.6
Current liabilities		4,113.4	5,265.1
Asset retirement obligations		698.6	480.5
Finance Lease, Liability, Payment, Due		429.4
Variable Interest Entity, Primary Beneficiary
VIE Assets and Liabilities [Abstract]
Net Property, Plant and Equipment		1,323.8	1,369.8
Current assets		65	63.6
Total Assets		1,388.8	1,433.4
Current liabilities		53.7	68.3
Asset retirement obligations		58.3	55.7
Finance Lease, Liability, Payment, Due		40.4	0
Total liabilities(1)(2)		$ 152.4	$ 124
[1] (1) Includes $1,323.8 million and $1,369.8 million in 2024 and 2023, respectively, of net property, plant and equipment assets, $65.0 million and $63.6 million in 2024 and 2023, respectively, of current assets of consolidated VIEs that may be used only to settle obligations of the consolidated VIEs. Refer to Note 4, "Noncontrolling Interests," for additional information.

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net Income Available to Common Shareholders	$ 739.7	$ 661.7	$ 749
Add: Dilutive effect of Equity Units	0	1.4	2
Net Income Available to Common Shareholders - Diluted	$ 738.1	$ 662.5	$ 751
Average common shares outstanding - Basic	454,200	416,100	407,100
Equity Units purchase contracts	0	29,800	30,200
Incremental Common Shares Attributable to Dilutive Effect of Equity Unit Purchase Agreements	0	900	3,200
Shares contingently issuable under employee stock plans	900	700	900
Shares restricted under employee stock plans	300	400	500
ATM Forward agreements	600	0	800
Average Common Shares - Diluted	456,000	447,900	442,700
Basic Earnings Per Share	$ 1.63	$ 1.59	$ 1.84
Diluted Earnings Per Share	$ 1.62	$ 1.48	$ 1.70
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	$ 1.6	$ 0.6	$ 0
Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic	$ 738.1	$ 661.1	$ 749

Equity (Narrative) (Details)

Equity (Narrative) (Details) - USD ($)							3 Months Ended		12 Months Ended
	Nov. 20, 2024	Sep. 30, 2024	Sep. 27, 2024	Sep. 17, 2024	Sep. 11, 2024	May 22, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Feb. 23, 2024	Dec. 31, 2023	Dec. 31, 2022	Nov. 19, 2024	Mar. 15, 2024	Feb. 01, 2024	Dec. 01, 2023	Jun. 15, 2023
Forward Contract Indexed to Issuer's Equity [Line Items]
Common Stock Aggregate Sale Price															$ 900,000,000
Derivative, Forward Price	$ 33.99	$ 34.32	$ 34.01	$ 25.77	$ 28.79	$ 28.87	$ 33.64			$ 25.78
Preferred Stock, Liquidation Preference Per Share																	$ 1,000
Preferred Stock, Par or Stated Value Per Share							$ 0.01	$ 0.01	$ 0.01		$ 0.01					$ 0.01
Purchase Contract Liability							$ 0	$ 0	$ 0		$ 0	$ 65,000,000
Equity Units purchase contracts									0		29,800,000	30,200,000
Common Stock, Shares, Issued																33,898,837
Preferred Stock, Shares Outstanding							0	40,000	0		40,000
Preferred Stock Redemption Premium									$ 14,000,000		$ 9,800,000
Series A Preferred Stock
Forward Contract Indexed to Issuer's Equity [Line Items]
Preferred Stock, Liquidation Preference, Value							$ 400,000,000	$ 400,000,000	$ 400,000,000		400,000,000	$ 400,000,000
Preferred Stock, Redemption Amount																	$ 400,000,000
Preferred Stock, Shares Outstanding																	400,000
Preferred Stock, Dividends Per Share, Declared								$ 28.25
Series B Preferred Stock
Forward Contract Indexed to Issuer's Equity [Line Items]
Preferred Stock, Liquidation Preference Per Share							$ 25,000		$ 25,000
Preferred Stock, Liquidation Preference, Value							$ 500,000,000	$ 500,000,000	$ 500,000,000		$ 500,000,000	$ 500,000,000
Preferred Stock, Dividends Per Share, Declared									$ 406.25		$ 1,625
Preferred Stock Redemption Premium									$ 14,000,000
Series B-1 Preferred Stock
Forward Contract Indexed to Issuer's Equity [Line Items]
Preferred Stock, Shares Issued							20,000		20,000					20,000
Preferred Stock, Par or Stated Value Per Share														$ 0.01
Preferred Stock, Redemption Amount														$ 500,000,000
Series C Preferred Stock
Forward Contract Indexed to Issuer's Equity [Line Items]
Preferred Stock, Liquidation Preference, Value							$ 863,000,000		$ 863,000,000
Preferred Stock, Shares Outstanding																862,500
At The Market Program
Forward Contract Indexed to Issuer's Equity [Line Items]
ATM Program Equity Remaining Available for Issuance									297,700,000
Forward February 23
Forward Contract Indexed to Issuer's Equity [Line Items]
Common Stock Aggregate Sale Price		$ 199,900,000
Forward Contract Indexed to Issuer's Equity, Shares										7,757,951
Forward May 22
Forward Contract Indexed to Issuer's Equity [Line Items]
Common Stock Aggregate Sale Price		$ 299,100,000
Forward Contract Indexed to Issuer's Equity, Shares						10,390,000
Forward September 27
Forward Contract Indexed to Issuer's Equity [Line Items]
Common Stock Aggregate Sale Price													$ 50,300,000
Forward Contract Indexed to Issuer's Equity, Shares			1,495,949
Forward September 30
Forward Contract Indexed to Issuer's Equity [Line Items]
Common Stock Aggregate Sale Price							$ 51,000,000		$ 51,000,000
Forward Contract Indexed to Issuer's Equity, Shares		1,500,000

Equity (Schedule of Stock by Cl

Equity (Schedule of Stock by Class - Preferred) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 01, 2023	Jun. 15, 2023
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share					$ 1,000
Preferred Stock, Shares Outstanding	40,000	0	40,000
Preferred Stock, Value, Outstanding	$ 486.1	$ 0	$ 486.1
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding					400,000
Preferred Stock, Dividends Per Share, Declared	$ 28.25
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share		$ 25,000
Preferred Stock, Dividends Per Share, Declared		$ 406.25	$ 1,625
Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding				862,500

Equity (Schedule of Equity Unit

Equity (Schedule of Equity Units) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Equity Units [Line Items]
Purchase Contract Liability	$ 0	$ 0	$ 65

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Short-term Debt [Line Items]
Line of Credit Facility, Amount Outstanding	$ 0	$ 0
Commercial paper outstanding	604.6	1,061
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	0	337.6
Cash from financing activities	337.6	9.6
Accounts receivable securitization fees	1.5	2.7	$ 2.5
Termination Loans	1,000	$ 1,000
Additional Term Credit	650
Second TCA Debt Interest Rate		6.50%
Debt Instrument, Interest Rate, Stated Percentage		6.41%
Accounts Receivable Program
Short-term Debt [Line Items]
Seasonal Limit	175
Commercial Paper
Short-term Debt [Line Items]
Revolving credit facility, maximum	$ 1,850	$ 1,500
Short-term Debt, Weighted Average Interest Rate, at Point in Time	4.73%	5.65%
Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, maximum	$ 1,850

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions							12 Months Ended
	Sep. 09, 2024	Jun. 24, 2024	May 16, 2024	Mar. 14, 2024	Jun. 08, 2023	Mar. 24, 2023	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Senior Notes							$ 12,103	$ 10,853
Interest rate on debt								6.41%
Debt Instrument, Convertible, Conversion Ratio							52.60%
Security interest and other subset of asset							$ 200
Asset sale covenant percentage of consolidated total assets							15%
Cross default provision on default relating to any indebtedness							$ 75
Percentage of additional subset of assets capped							10%
Revolving credit percentage requirement in NIPSCO							70%
Junior Subordinated Notes							$ 1,000	$ 0
NiSource
Debt Instrument [Line Items]
Senior Notes					$ 450
NiSource | Senior Notes
Debt Instrument [Line Items]
Senior Notes					300	$ 750	$ 1,050
Proceeds from Debt, Net of Issuance Costs					$ 742.5	$ 742.2
Debt, Weighted Average Interest Rate					5.25%	5.25%
NiSource | Medium-Term Note
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate							7.99%
NiSource | Unsecured Debt
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate					5.40%
NiSource | 5.35% Notes Due 2034
Debt Instrument [Line Items]
Senior Notes				$ 650			$ 650	0
Proceeds from Debt, Net of Issuance Costs				$ 642.6
Debt, Weighted Average Interest Rate				5.35%			5.35%
NiSource | 6.95% Notes due 2054
Debt Instrument [Line Items]
Proceeds from Debt, Net of Issuance Costs			$ 493.4
Debt, Weighted Average Interest Rate			6.95%				6.95%
Debt Instrument, Basis Spread on Variable Rate			2.451%
Junior Subordinated Notes			$ 500				$ 500	0
NiSource | 5.20% Notes Due 2029
Debt Instrument [Line Items]
Senior Notes		$ 600					$ 600	0
Proceeds from Debt, Net of Issuance Costs		$ 593.7
Debt, Weighted Average Interest Rate		5.20%					5.20%
NiSource | 6.375% Notes due 2054
Debt Instrument [Line Items]
Proceeds from Debt, Net of Issuance Costs	$ 493.6
Debt, Weighted Average Interest Rate	6.375%						6.375%
Debt Instrument, Basis Spread on Variable Rate	2.527%
Junior Subordinated Notes	$ 500						$ 500	$ 0
NIPSCO | Medium-Term Note
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate							7.644%
Columbia Of Massachusetts | Medium-Term Note
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate							6.373%
Maximum
Debt Instrument [Line Items]
Cross default provision on default relating to any indebtedness							$ 50
Minimum
Debt Instrument [Line Items]
Cross default provision on default relating to any indebtedness							$ 5
Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Debt Instrument, Convertible, Conversion Ratio							70%

Long-Term Debt (Schedule of Con

Long-Term Debt (Schedule of Consolidated Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 09, 2024	Jun. 24, 2024	May 16, 2024	Mar. 14, 2024	Dec. 31, 2023	Jun. 08, 2023
Debt Instrument [Line Items]
Medium-Term Notes	$ 102					$ 102
Finance Lease, Liability	246.2					205.4
Senior Notes	12,103					10,853
Junior Subordinated Notes	1,000					0
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	(95.5)					(81.1)
Long-Term Debt, Current Maturities	(1,281.2)					(23.8)
Long-term Debt, Excluding Current Maturities	13,355.7					11,079.3
Long-term Debt and Lease Obligation	$ 12,074.5					11,055.5
NiSource
Debt Instrument [Line Items]
Senior Notes							$ 450
NiSource | 0.95% Notes Due 2025
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	0.95%
Senior Notes	$ 1,250					1,250
NiSource | 3.49% Notes due 2027
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.49%
Senior Notes	$ 1,000					1,000
NiSource | 6.78% Notes Due 2027
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.78%
Senior Notes	$ 3					3
NiSource | 2.95% Notes Due 2029
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	2.95%
Senior Notes	$ 750					750
NiSource | 3.60% Notes Due 2030
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.60%
Senior Notes	$ 1,000					1,000
NiSource | 1.70% Notes Due 2031
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	1.70%
Senior Notes	$ 750					750
NiSource | 6.25% Notes Due 2040
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.25%
Senior Notes	$ 152.6					152.6
NiSource | 5.95% Notes Due 2041
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.95%
Senior Notes	$ 347.4					347.4
NiSource | 5.80% Notes Due 2042
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.80%
Senior Notes	$ 250					250
NiSource | 5.25% Notes Due 2043
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.25%
Senior Notes	$ 500					500
NiSource | 4.80% Notes due 2044
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.80%
Senior Notes	$ 750					750
NiSource | 5.65% Notes Due 2045
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.65%
Senior Notes	$ 500					500
NiSource | 4.375% Notes due 2047
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.375%
Senior Notes	$ 1,000					1,000
NiSource | 3.95% Notes Due 2048
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.95%
Senior Notes	$ 750					750
NiSource | Medium-Term Note
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	7.99%
Medium-Term Notes	$ 29					29
NiSource | 5.00% Notes Due 2052
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5%
Senior Notes	$ 350					350
NiSource | 5.25% Notes Due 2028
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.25%
Senior Notes	$ 1,050					1,050
NiSource | 5.40% Notes Due 2033
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.40%
Senior Notes	$ 450					450
NiSource | 5.20% Notes Due 2029
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.20%		5.20%
Senior Notes	$ 600		$ 600			0
NiSource | 5.35% Notes Due 2034
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.35%				5.35%
Senior Notes	$ 650				$ 650	0
NiSource | 6.95% Notes due 2054
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.95%			6.95%
Junior Subordinated Notes	$ 500			$ 500		0
NiSource | 6.375% Notes due 2054
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.375%	6.375%
Junior Subordinated Notes	$ 500	$ 500				0
Columbia Of Massachusetts | Medium-Term Note
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.373%
Medium-Term Notes	$ 15					15
NIPSCO | Medium-Term Note
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	7.644%
Medium-Term Notes	$ 58					58
NIPSCO | Finance Leases
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.25%
Finance Lease, Liability	$ 124.3					61.2
Columbia Of Ohio | Finance Leases
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.15%
Finance Lease, Liability	$ 85.6					90.3
NiSource Corporate Services | Finance Leases
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.47%
Finance Lease, Liability	$ 14.6					30.5
Columbia Of Virginia | Finance Leases
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	6.19%
Finance Lease, Liability	$ 15.2					16.1
Columbia Of Kentucky | Finance Leases
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.36%
Finance Lease, Liability	$ 0.1					0.2
Columbia Of Pennsylvania | Finance Leases
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	4.47%
Finance Lease, Liability	$ 6.4					$ 7.1

Property, Plant and Equipment_2

Property, Plant and Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Depreciation	$ 820.4	$ 756.9	$ 685
Regulatory Deferral - Joint Venture	58.9	12.5	11
Capitalized Computer Software, Amortization	85.2	77.5	53.1
Capitalized Computer Software, Gross	236.1	205.6
Capitalized Cloud Computing, Amortization	17.7	12.6	$ 11.1
Capitalized Cloud Computing, Gross	$ 77.5	$ 32.2

Property, Plant And Equipment_3

Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	$ 34,152.9	$ 30,482.1
Accumulated Depreciation and Amortization	(8,699)	(8,207.2)
Net Property, Plant and Equipment	25,453.9	22,274.9
Gas Distribution Utility
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	20,007.2	18,154.5
Accumulated Depreciation and Amortization	(4,166.8)	(3,924.4)
Electric Utility
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	8,666.8	7,907.9
Accumulated Depreciation and Amortization	(2,707.8)	(2,709.5)
Common Utility
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	248.1	274.2
Accumulated Depreciation and Amortization	(163.4)	(174.2)
Construction Work In Process
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	2,084.7	1,261.1
Renewable Generation Assets
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	1,434.2	1,434.4
Accumulated Depreciation and Amortization	(110.4)	(64.5)
Non-Utility And Other
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	1,711.9	1,450
Accumulated Depreciation and Amortization	$ (1,550.6)	$ (1,334.6)

Property, Plant And Equipment P

Property, Plant And Equipment Property, Plant and Equipment (Schedule of Depreciation Provisions For Utility Plant as a Percentage of the Original Cost) (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Electric Operations
Property, Plant and Equipment [Line Items]
Depreciation Provisions For Utility Plant Percentage	3%	3%	2.70%
Gas Distribution Operations
Property, Plant and Equipment [Line Items]
Depreciation Provisions For Utility Plant Percentage	2.60%	2.50%	2.40%

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 1,485.9	$ 1,485.9
Gas Distribution Operations
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 1,485.9	$ 1,485.9

Asset Retirement Obligations (C

Asset Retirement Obligations (Changes In Company's Liability For Asset Retirement Obligations) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Beginning Balance		$ 480.5
Accretion recorded as a regulatory asset		25.3	$ 20
Additions		189.9	23.5
Settlements		(72.5)	(41.6)
Change in estimated cash flows		87.5	37.6
Asset Retirement Obligation	$ 783.2	783.2	553	$ 513.5
Ending Balance	698.6	698.6	480.5
Assets recorded for asset retirement obligations		$ 277.4	$ 61.1	$ 6.3
Asset Retirement Obligation, Period Increase (Decrease)	$ 149.7

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	Dec. 31, 2024 USD ($) MW	Dec. 31, 2023 USD ($)
Regulatory Assets and Liabilities Disclosure [Line Items]
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	$ 671.3	$ 716.4
COVID-19 related regulatory asset	2,477.3	2,460.2
Regulatory Liabilities	1,581.7	1,789.3
Annual Revenue Increase from Joint Stipulation and Proposed Settlements	$ 28.2
Minimum
Regulatory Assets and Liabilities Disclosure [Line Items]
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	15 years
Maximum
Regulatory Assets and Liabilities Disclosure [Line Items]
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided	75 years
Overrecovered Gas And Fuel Costs
Regulatory Assets and Liabilities Disclosure [Line Items]
Regulatory Liabilities	$ 21.4	$ 144.5
NIPSCO
Regulatory Assets and Liabilities Disclosure [Line Items]
Gas Peaker Capacity | MW	400

Regulatory Matters (Regulatory

Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Regulated Operations [Line Items]
Total Assets	$ 2,477.3	$ 2,460.2
Regulatory Assets, Current	319.9	214.3
Regulatory Assets, Noncurrent	2,157.4	2,245.9
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Regulated Operations [Line Items]
Total Assets	485.3	561.6
Other Postretirement Costs
Regulated Operations [Line Items]
Total Assets	45.3	59.7
Environmental Costs
Regulated Operations [Line Items]
Total Assets	42.8	40.6
Regulatory Effects Of Accounting For Income Taxes
Regulated Operations [Line Items]
Total Assets	172	163.5
Underrecovered Gas And Fuel Costs
Regulated Operations [Line Items]
Total Assets	82.3	12.7
Depreciation
Regulated Operations [Line Items]
Total Assets	214.9	201.9
Post-In Service Carrying Charges
Regulated Operations [Line Items]
Total Assets	280.8	269.9
Safety Activity Costs
Regulated Operations [Line Items]
Total Assets	203.7	206.6
DSM Program
Regulated Operations [Line Items]
Total Assets	17.8	25
Retired coal generating stations
Regulated Operations [Line Items]
Total Assets	617	682
Deferred Derivative Gain (Loss)
Regulated Operations [Line Items]
Total Assets	6.5	24.4
Deferred Property Taxes
Regulated Operations [Line Items]
Total Assets	75.9	72.3
Renewable Energy Program
Regulated Operations [Line Items]
Total Assets	81.3	60.8
Other Assets
Regulated Operations [Line Items]
Total Assets	105.8	79.2
Work and Asset Management enterprise resourcing system
Regulated Operations [Line Items]
Total Assets	21.5	0
Customer Assistance Programs
Regulated Operations [Line Items]
Total Assets	$ 24.4	$ 0

Regulatory Matters (Regulator_2

Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Regulated Operations [Line Items]
Regulatory Liabilities	$ 1,581.7	$ 1,789.3
Regulatory Liability, Current	150.5	278.6
Regulatory Liability, Noncurrent	1,431.2	1,510.7
Deferred Derivative Gain (Loss)
Regulated Operations [Line Items]
Regulatory Liabilities	28.7	23.3
Customer Assistance Programs
Regulated Operations [Line Items]
Regulatory Liabilities	9.4	19.8
Rate Refunds
Regulated Operations [Line Items]
Regulatory Liabilities	16.6	16.1
Off-Systems sales sharing
Regulated Operations [Line Items]
Regulatory Liabilities	21.4	19
HLBV Adjustments under ASC 980
Regulated Operations [Line Items]
Regulatory Liabilities	77	18.1
Overrecovered Gas And Fuel Costs
Regulated Operations [Line Items]
Regulatory Liabilities	21.4	144.5
Cost Of Removal
Regulated Operations [Line Items]
Regulatory Liabilities	482.8	597.2
Regulatory Effects Of Accounting For Income Taxes
Regulated Operations [Line Items]
Regulatory Liabilities	827	849.9
Other Postretirement Costs
Regulated Operations [Line Items]
Regulatory Liabilities	40.4	54
Other Liabilities
Regulated Operations [Line Items]
Regulatory Liabilities	$ 57	$ 47.4

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of COVID-19 Regulatory Impact) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Regulatory Matters COVID [Line Items]
COVID-19 related regulatory asset	$ 2,477.3	$ 2,460.2

Risk Management Activities (Nar

Risk Management Activities (Narrative) (Details) mMDth in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) mMDth	Dec. 31, 2023 USD ($) mMDth	Jun. 08, 2023 USD ($)	Mar. 24, 2023 USD ($)
Derivative [Line Items]
Limit of GCA Volumes	20%
Derivative Asset	$ 27	$ 23.3
Senior Notes	12,103	10,853
Derivative Asset, Subject to Master Netting Arrangement, after Offset	$ 23.5	13.9
Customer annual demand	20%
Other Current Assets
Derivative [Line Items]
Derivative Asset	$ 9.1	$ 1.1
NiSource
Derivative [Line Items]
Senior Notes			$ 450
Senior Notes | NiSource
Derivative [Line Items]
Senior Notes	$ 1,050		$ 300	$ 750
Debt, Weighted Average Interest Rate			5.25%	5.25%
Minimum
Derivative [Line Items]
Commodity Contract Length	1 year
Maximum
Derivative [Line Items]
Commodity Contract Length	3 years
Natural Gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | mMDth	77.8	76.1

Risk Management Activities (Sch

Risk Management Activities (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Derivative Asset	$ 27	$ 23.3
Derivative Liability	3.5	9.4
Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset	9.1	1.1
Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability	2.3	7.5
Other Assets
Derivatives, Fair Value [Line Items]
Derivative Asset	17.9	22.2
Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability	1.2	1.9
Commodity price risk programs | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset	9.1	1.1
Commodity price risk programs | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability	2.3	7.5
Commodity price risk programs | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Asset	17.9	22.2
Commodity price risk programs | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability	$ 1.2	$ 1.9

Risk Management Activities (S_2

Risk Management Activities (Schedule of Cash Flow Hedges in AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net current-period other comprehensive income (loss)	$ 3.2	$ 3.5	$ 89.7
Interest rate risk programs
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net current-period other comprehensive income (loss)	$ (0.4)

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value Disclosure [Line Items]
Transfers between Fair Value Hierarchies	$ 0	$ 0
Allowance for Credit Loss	0.1	0.6
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease)	0
Debt Securities, Available-for-Sale, Realized Gain (Loss)	(2.3)	(1)
U.S. Treasury debt securities
Fair Value Disclosure [Line Items]
Allowance for Credit Loss		0
Corporate/Other debt securities
Fair Value Disclosure [Line Items]
Allowance for Credit Loss	0.1	$ 0.6
Available-for-sale securities, maturities of less than a year	$ 10.9

Fair Value (Fair Value Of Finan

Fair Value (Fair Value Of Financial Assets And Liabilities Measured On A Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Risk management assets	$ 27	$ 23.3
Available-for-sale debt securities	86.7	159.1
Total	193.8	182.4
Risk management liabilities	3.5	9.4
Total	3.5	9.4
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	80.1
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Risk management assets	0	0
Available-for-sale debt securities	0	0
Total	80.1	0
Risk management liabilities	0	0
Total	0	0
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	80.1
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Risk management assets		23.3
Available-for-sale debt securities	86.7	159.1
Total	113.7	182.4
Derivative Liability Statement Of Financial Position Extensible Enumeration Not Disclosed Flag		9.4
Risk management liabilities	3.5
Total	3.5	9.4
Derivative Asset Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	27
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Risk management assets	0	0
Available-for-sale debt securities	0	0
Total	0	0
Risk management liabilities	0	0
Total	0	$ 0
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	$ 0

Fair Value (Available-For-Sale

Fair Value (Available-For-Sale Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value Disclosure [Line Items]
Amortized Cost	$ 91.9	$ 169
Gross Unrealized Gains	0.5	0.8
Gross Unrealized Losses	5.6	10.1
Allowance for Credit Loss	(0.1)	(0.6)
Fair Value	86.7	159.1
U.S. Treasury debt securities
Fair Value Disclosure [Line Items]
Amortized Cost		63.8
Gross Unrealized Gains		0
Gross Unrealized Losses		3.2
Allowance for Credit Loss		0
Fair Value		60.6
Debt Securities, Available-for-sale, Unrealized Loss Position		58.7
Corporate/Other debt securities
Fair Value Disclosure [Line Items]
Amortized Cost	91.9	105.2
Gross Unrealized Gains	0.5	0.8
Gross Unrealized Losses	5.6	6.9
Allowance for Credit Loss	(0.1)	(0.6)
Fair Value	86.7	98.5
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 70.1	$ 74.8

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Long-term debt (including current portion), Carrying Amount	$ 13,355.7	$ 11,079.3
Long-term debt (including current portion), Estimated Fair Value	$ 12,505.2	$ 10,370.9

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 369.4	$ 422.9
Deferred Tax Assets, Valuation Allowance	6.4	6.4
Book income before income taxes	1,002.8	813.9	$ 956.4
Tax expense (benefit) at statutory federal income tax rate, value	$ 210.6	$ 170.8	$ 200.8
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21%	21%	21%
State income taxes, net of federal income tax benefit, value	$ 11.7	$ 13.7	$ 4.5
State income taxes, net of federal income tax benefit, rate	1.20%	1.70%	0.50%
Amortization of regulatory liabilities, value	$ (11.1)	$ (38.2)	$ (38.5)
Amortization of regulatory liabilities, rate	(1.10%)	(4.70%)	(4.00%)
Effective Income Tax Rate Reconciliation, Deduction, Employee Stock Ownership Plan Dividend, Amount	$ (1.3)	$ (1.3)	$ (1.2)
Employee stock ownership plan dividends and other compensation, rate	(0.10%)	(0.20%)	(0.10%)
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ (23.3)	$ (4.9)	$ (2.3)
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	(2.30%)	(0.60%)	(0.20%)
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent	(2.70%)
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount	$ (27.3)	$ 0
Other adjustments, value	$ (1.2)	$ (0.6)	$ 1.3
Other adjustments, rate	(0.20%)	0.10%	0%
Income Taxes	$ 158.1	$ 139.5	$ 164.6
Effective Income Tax Rate Reconciliation, Percent	15.80%	17.10%	17.20%
Deferred Federal Income Tax Expense (Benefit)	$ (389.9)
Increase (Decrease) in Tax Expense	18.6	$ (25.1)
Operating Loss Carryforwards	21.7	21.7	$ 21.7
Decrease in Amortization of Regulatory Liabilities	$ 7.9
NiSource
Income Taxes [Line Items]
Subsidiary, Ownership Percentage, Parent	80.10%
Investment Tax Credit Carryforward
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 0
Deferred Federal Income Tax Expense (Benefit)	(2.2)
Investment Tax Credit	0.1	$ 2.1	$ 0
Federal production tax credits
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	0
Deferred Federal Income Tax Expense (Benefit)	(1)
Federal other credit
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	0
Deferred Federal Income Tax Expense (Benefit)	(17.3)
State and Local Jurisdiction
Income Taxes [Line Items]
Deferred Federal, State and Local, Tax Expense (Benefit)	81.9
Domestic Tax Jurisdiction
Income Taxes [Line Items]
Deferred Federal Income Tax Expense (Benefit)	(287.5)
State and Local Jurisdiction
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	6.4
Operating Loss Carryforwards	2,024.4
Domestic Tax Jurisdiction
Income Taxes [Line Items]
Deferred Tax Assets, Valuation Allowance	0
Operating Loss Carryforwards	$ 1,369.1

Income Taxes (Schedule Of Compo

Income Taxes (Schedule Of Components Of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Current
Federal	$ (19.3)	$ 0	$ 0.4
State	9.4	5.3	7.3
Total Current	(9.9)	5.3	7.7
Deferred
Federal	389.9
State	2.6	22.5	(23)
Total Deferred	168.8	135.2	158
Deferred Investment Credits	(0.8)	(1)	(1.1)
Income Taxes	158.1	139.5	164.6
Investment Tax Credit Carryforward
Deferred
Federal	2.2
Investment Tax Credit	(0.1)	(2.1)	0
Operating loss carryforward and investment credits
Deferred
Federal	105.9	49.7	87.9
Utilization expense of operating loss carryforwards
Deferred
Federal	$ 60.4	$ 65.1	$ 93.1

Income Taxes (Schedule Of Reaso

Income Taxes (Schedule Of Reasons Behind Differences In Computation Of Total Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Reasons Behind Differences in Computation of Total Income Taxes [Line Items]
Book income before income taxes	$ 1,002.8	$ 813.9	$ 956.4
Tax expense (benefit) at statutory federal income tax rate, value	$ 210.6	$ 170.8	$ 200.8
Tax expense (benefit) at statutory federal income tax rate, rate	21%	21%	21%
Increases (reductions) in taxes resulting from:
State income taxes, net of federal income tax benefit, value	$ 11.7	$ 13.7	$ 4.5
State income taxes, net of federal income tax benefit, rate	1.20%	1.70%	0.50%
Amortization of regulatory liabilities, value	$ (11.1)	$ (38.2)	$ (38.5)
Amortization of regulatory liabilities, rate	1.10%	4.70%	4%
Employee stock ownership plan dividends and other compensation, value	$ (1.3)	$ (1.3)	$ (1.2)
Employee stock ownership plan dividends and other compensation, rate	(0.10%)	(0.20%)	(0.10%)
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ (23.3)	$ (4.9)	$ (2.3)
Effective Income Tax Rate Reconciliation, Tax Credit, Percent	(2.30%)	(0.60%)	(0.20%)
Other adjustments, value	$ (1.2)	$ (0.6)	$ 1.3
Other adjustments, rate	0.20%	(0.10%)	0%
Income Taxes	$ 158.1	$ 139.5	$ 164.6
Income Taxes, rate	15.80%	17.10%	17.20%

Income Taxes (Schedule Of Princ

Income Taxes (Schedule Of Principal Components Of Net Deferred Tax Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred Tax Liabilities
Accelerated depreciation and other property differences	$ 1,419.4	$ 1,384.8
Partnership basis differences	1,328.6	1,241.9
Other regulatory assets	210.1	212.1
Total Deferred Tax Liabilities	2,958.1	2,838.8
Deferred Tax Assets
Other regulatory liabilities and deferred investment tax credits (including TCJA)	170.4	182.2
Pension and other postretirement/postemployment benefits	58.8	58.6
Net operating loss carryforward and AMT credit carryforward	369.4	422.9
Environmental liabilities	12.2	10.1
Other accrued liabilities	43.4	40.3
Other, net	28.7	50.7
Total Deferred Tax Assets	682.9	764.8
Deferred Tax Assets, Valuation Allowance	(6.4)	(6.4)
Deferred Tax Assets, Net of Valuation Allowance	676.5	758.4
Net Deferred Tax Liabilities	$ 2,281.6	$ 2,080.4

Income Taxes (Schedule of Unrec

Income Taxes (Schedule of Unrecognized Tax Benefits Roll Forward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits - Opening Balance	$ 21.7	$ 21.7	$ 21.7
Gross decreases - tax positions in prior period	0	0	0
Gross increases - current period tax positions	0	0	0
Unrecognized Tax Benefits - Ending Balance	21.7	21.7	21.7
Offset for net operating loss carryforwards	(21.7)	(21.7)	(21.7)
Balance - Less Net Operating Loss Carryforwards	0	0	$ 0
Increase (Decrease) in Tax Expense	$ 18.6	$ (25.1)

Pension and Other Postretirem_3

Pension and Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
COVID-19 related regulatory asset	$ 2,477.3	$ 2,460.2
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	1,278.4	1,390.9
Funded status of plan	(49.1)	(25)
Employer contributions	2.4	3.1
Settlement loss	7.2	$ 9.2	$ 12.4
Expected contribution	$ 2.3
Expected return on plan assets	7.02%	7%	4.80%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Funded status of plan	$ 193.1	$ 232.3
Employer contributions	23.6	23.4
Settlement loss	0	$ 0	$ 0
Expected contribution	$ 21.3
Expected return on plan assets	7.06%	6.96%	5.72%
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Defined Benefit Plan Disclosure [Line Items]
COVID-19 related regulatory asset	$ 485.3	$ 561.6

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits (Schedule Of Portfolio Asset Mix) (Details)	Dec. 31, 2024	Dec. 31, 2023
Minimum | Domestic Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%	10%
Minimum | Domestic Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Minimum | International Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5%	5%
Minimum | International Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Minimum | Fixed Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	65%
Minimum | Fixed Income | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20%
Minimum | Real Estate [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Minimum | Real Estate [Member] | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Minimum | Real Estate | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Minimum | Real Estate | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Minimum | Short-Term Investments | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Minimum | Short-Term Investments | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Minimum | Private Equity | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Minimum | Private Equity | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Maximum | Domestic Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30%	30%
Maximum | Domestic Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	55%	55%
Maximum | International Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15%	15%
Maximum | International Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	25%	25%
Maximum | Fixed Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	75%
Maximum | Fixed Income | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100%
Maximum | Real Estate [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Maximum | Real Estate [Member] | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%
Maximum | Real Estate | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Maximum | Real Estate | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Maximum | Short-Term Investments | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%	10%
Maximum | Short-Term Investments | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%	10%
Maximum | Private Equity | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3%	3%
Maximum | Private Equity | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%

Pension and Other Postretirem_5

Pension and Other Postretirement Benefits (Schedule of Plan Asset Mix Prior Year) (Details)	Dec. 31, 2024	Dec. 31, 2023
Pension Plan | Domestic Equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%	10%
Pension Plan | Domestic Equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30%	30%
Pension Plan | International Equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5%	5%
Pension Plan | International Equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15%	15%
Pension Plan | Fixed Income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		65%
Pension Plan | Fixed Income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		75%
Pension Plan | Real Estate | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Pension Plan | Real Estate | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Pension Plan | Short-Term Investments | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Pension Plan | Short-Term Investments | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%	10%
Pension Plan | Private Equity | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Pension Plan | Private Equity | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3%	3%
Other Postretirement Benefits | Domestic Equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Other Postretirement Benefits | Domestic Equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	55%	55%
Other Postretirement Benefits | International Equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Other Postretirement Benefits | International Equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	25%	25%
Other Postretirement Benefits | Fixed Income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		20%
Other Postretirement Benefits | Fixed Income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		100%
Other Postretirement Benefits | Real Estate | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Other Postretirement Benefits | Real Estate | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		0%
Other Postretirement Benefits | Short-Term Investments | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Other Postretirement Benefits | Short-Term Investments | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10%	10%
Other Postretirement Benefits | Private Equity | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%
Other Postretirement Benefits | Private Equity | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0%	0%

Pension and Other Postretirem_6

Pension and Other Postretirement Benefits (Schedule Of Pension Plan And Postretirement Plan Asset Mix) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 1,579.9	$ 1,663.6
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	100%	100%
Noncurrent assets	$ 66.5	$ 44.1
Pension Plan | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,336.5	$ 1,426.8	$ 1,422.8
Noncurrent assets	$ 1,336.4
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	100%	100%
Noncurrent assets	$ 0	$ 0
Other Postretirement Benefits | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	243.2	236.5	$ 224.9
Noncurrent assets	243.5
Domestic Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 258.9	$ 261.7
Percentage of total asset	19.40%	18.30%
Domestic Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 99.6	$ 93.7
Percentage of total asset	40.90%	39.60%
International Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 122.5	$ 141.9
Percentage of total asset	9.20%	9.90%
International Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 40.7	$ 40.7
Percentage of total asset	16.70%	17.20%
Fixed Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 891.2	$ 939.9
Percentage of total asset	66.70%	65.90%
Fixed Income | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 96.5	$ 97
Percentage of total asset	39.60%	41%
Real Estate | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 4	$ 4
Percentage of total asset	0.30%	0.30%
Real Estate | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 0	$ 0
Percentage of total asset	0%	0%
Cash/Other [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 59.8	$ 79.3
Percentage of total asset	4.40%	5.60%
Cash/Other [Member] | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 6.7	$ 5.1
Percentage of total asset	2.80%	2.20%
Commingled Funds | Short-Term Money Markets | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 45.9	$ 65.3
Commingled Funds | Short-Term Money Markets | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	6.7	5.2
Commingled Funds | International Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	65.3	102.3
Commingled Funds | International Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	24.2	22.8
Commingled Funds | Fixed Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	214.1	242.2
Commingled Funds | United States Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	202.8	148.5
Commingled Funds | United States Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 12.2	$ 11.4

Pension and Other Postretirem_7

Pension and Other Postretirement Benefits (Schedule Of Fair Value Of Pension Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 360.6
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 323.7
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	677	695.2
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,579.9	1,663.6
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	1,327.6	1,421
Pension Plan | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items		154.7
Pension Plan | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	114.4
Pension Plan | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	677.1	697.9
Pension Plan | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	0	0
Pension Plan | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,336.5	1,426.8	$ 1,422.8
Pension Plan | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1.2	2.2
Pension Plan | Cash [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		2
Pension Plan | Cash [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1.1
Pension Plan | Cash [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0.1	0.2
Pension Plan | Cash [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | International Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	122.5	141.9
Pension Plan | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	891.2	939.9
Pension Plan | Equity Securities [Member] | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		1.1
Pension Plan | Equity Securities [Member] | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		1.1
Pension Plan | Equity Securities [Member] | United States Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Equity Securities [Member] | United States Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Fixed Income | Government
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	186.8	213.1
Pension Plan | Fixed Income | Government | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Fixed Income | Government | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Fixed Income | Government | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	186.8	213.1
Pension Plan | Fixed Income | Government | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Fixed Income | Corporate/Other debt securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	486.6	482.2
Pension Plan | Fixed Income | Corporate/Other debt securities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Fixed Income | Corporate/Other debt securities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Fixed Income | Corporate/Other debt securities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	486.6	482.2
Pension Plan | Fixed Income | Corporate/Other debt securities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Fixed Income | Mortgages/ Asset backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	3.6	2.4
Pension Plan | Fixed Income | Mortgages/ Asset backed securities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Fixed Income | Mortgages/ Asset backed securities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	3.6	2.4
Pension Plan | Fixed Income | Mortgages/ Asset backed securities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	65.3	102.3
Pension Plan | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Commingled Funds | International Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | International Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	214.1	242.2
Pension Plan | Commingled Funds | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Commingled Funds | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Commingled Funds | Fixed Income | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | Fixed Income | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	202.8	148.5
Pension Plan | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Commingled Funds | United States Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | United States Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | Short-Term Money Markets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	45.9	65.3
Pension Plan | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Commingled Funds | Short-Term Money Markets | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Commingled Funds | Short-Term Money Markets | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	3.1	4.8
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0.8	1.2
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0.1	0.1
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	4	4
Pension Plan | Real Estate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Pension Plan | Real Estate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Pension Plan | Real Estate [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Real Estate [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Mutual Funds [Member] | International Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	57.2	38.5
Pension Plan | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		38.5
Pension Plan | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	57.2
Pension Plan | Mutual Funds [Member] | International Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Mutual Funds [Member] | International Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	56.1	113.1
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		113.1
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	56.1
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	243.5	236.8
Other Postretirement Benefits | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items		197.4
Other Postretirement Benefits | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	200.4
Other Postretirement Benefits | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	0	0
Other Postretirement Benefits | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	0	0
Other Postretirement Benefits | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	243.2	236.5	$ 224.9
Other Postretirement Benefits | International Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	40.7	40.7
Other Postretirement Benefits | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	96.5	97
Other Postretirement Benefits | Due To Brokers Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(0.1)	(2.7)
Other Postretirement Benefits | Due To Brokers Net [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Other Postretirement Benefits | Due To Brokers Net [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Other Postretirement Benefits | Due To Brokers Net [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	(0.1)	(2.7)
Other Postretirement Benefits | Due To Brokers Net [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Accrued Investment Income Dividends [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	8.9	8.5
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	8.9	8.5
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	24.2	22.8
Other Postretirement Benefits | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Other Postretirement Benefits | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Other Postretirement Benefits | Commingled Funds | International Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Commingled Funds | International Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Commingled Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	12.2	11.4
Other Postretirement Benefits | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Other Postretirement Benefits | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Other Postretirement Benefits | Commingled Funds | United States Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Commingled Funds | United States Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	6.7	5.2
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Mutual Funds [Member] | International Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	16.5	18
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		18
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	16.5
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	96.5	97
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		97
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	96.5
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	87.4	82.4
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		82.4
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	87.4
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	0	0
Underfunded Plan [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 1,336.4	$ 1,426.8

Pension and Other Postretirem_8

Pension and Other Postretirement Benefits (Schedule of Net Asset Value Per Share) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value By Input	$ 579.2	$ 607.8
Private Equity and Real Estate Limited Partnerships
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value By Input	8	10.1
Commingled Funds | Short-Term Money Markets
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value By Input	$ 52.6	$ 70.5
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily	Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day	1 day
Commingled Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value By Input	$ 215	$ 159.9
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily	Daily
Commingled Funds | United States Equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	5 days	5 days
Commingled Funds | United States Equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day	1 day
Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value By Input	$ 89.5	$ 125.1
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Monthly	Monthly
Commingled Funds | International Equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	30 days	30 days
Commingled Funds | International Equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	10 days	10 days
Commingled Funds | Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value By Input	$ 214.1	$ 242.2
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily	Daily
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	3 days	3 days

Pension and Other Postretirem_9

Pension and Other Postretirement Benefits (Schedule Of Reconciliation Of The Plans Funded Status And Amounts Reflected) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liabilities	$ (192.1)	$ (231.3)
COVID-19 related regulatory asset	2,477.3	2,460.2
Regulatory Liabilities	1,581.7	1,789.3
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Defined Benefit Plan Disclosure [Line Items]
Regulatory Liabilities	0	0
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Defined Benefit Plan Disclosure [Line Items]
COVID-19 related regulatory asset	485.3	561.6
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	1,663.6
Fair value of plan assets at end of year	1,579.9	1,663.6
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	1,401.8	1,427.4
Service cost	21.9	20.5	$ 27.8
Interest cost	64.9	68.4	40.5
Plan participants' contributions	0	0
Plan amendments	0	0
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(64.8)	27.4
Defined Benefit Plan, Benefit Obligation, Benefits Paid	136.4	141.9
Estimated benefits paid by incurred subsidy	0	0
Projected benefit obligation at end of year	1,287.4	1,401.8	1,427.4
Actual return on plan assets	43.7	142.8
Employer contributions	2.4	3.1
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0	0
Benefits paid	(136.4)	(141.9)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	49.1	25
Noncurrent assets	66.5	44.1
Current liabilities	(2.3)	(2.2)
Noncurrent liabilities	(15.1)	(16.9)
Net amount recognized at end of year	49.1	25
Unrecognized prior service cost	0.3	0.3
Unrecognized actuarial loss	451.4	500.4
Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability	451.7	500.7
Pension Plan | Underfunded Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	1,382.7
Projected benefit obligation at end of year	1,269.9	1,382.7
Fair value of plan assets at beginning of year	1,426.8
Fair value of plan assets at end of year	1,336.4	1,426.8
Defined Benefit Plan, Funded (Unfunded) Status of Plan	66.5	44.1
Pension Plan | Underfunded Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	19.1
Projected benefit obligation at end of year	17.4	19.1
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(17.4)	(19.1)
Pension Plan | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	1,426.8	1,422.8
Fair value of plan assets at end of year	1,336.5	1,426.8	1,422.8
Noncurrent assets	1,336.4
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	468.8	449
Service cost	5	5.1	6.5
Interest cost	22	21.8	12
Plan participants' contributions	3.6	4.2
Plan amendments	0	3.4
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	(22.5)	29.1
Defined Benefit Plan, Benefit Obligation, Benefits Paid	40.7	44.3
Estimated benefits paid by incurred subsidy	0.1	0.5
Projected benefit obligation at end of year	436.3	468.8	449
Actual return on plan assets	20	28.2
Employer contributions	23.6	23.4
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	3.8	4.3
Benefits paid	(40.7)	(44.3)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(193.1)	(232.3)
Noncurrent assets	0	0
Current liabilities	(1)	(1)
Net amount recognized at end of year	(193.1)	(232.3)
Unrecognized prior service cost	3.8	2.1
Unrecognized actuarial loss	47	76.6
Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability	50.8	78.7
Other Postretirement Benefits | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	236.5	224.9
Fair value of plan assets at end of year	243.2	$ 236.5	$ 224.9
Noncurrent assets	$ 243.5

Pension and Other Postretire_10

Pension and Other Postretirement Benefits (Schedule of Benefit Obligations in Excess of Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 1,278.4	$ 1,390.9
Defined Benefit Plan, Benefit Obligation	1,287.4	1,401.8	$ 1,427.4
Defined Benefit Plan, Funded (Unfunded) Status of Plan	49.1	25
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation	436.3	468.8	$ 449
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(193.1)	(232.3)
Underfunded Plan [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	17.4	19.1
Defined Benefit Plan, Benefit Obligation	17.4	19.1
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(17.4)	(19.1)
Underfunded Plan [Member] | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	1,261	1,371.8
Defined Benefit Plan, Benefit Obligation	1,269.9	1,382.7
Defined Benefit Plan, Plan Assets, Amount	1,336.4	1,426.8
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ 66.5	$ 44.1

Pension and Other Postretire_11

Pension and Other Postretirement Benefits (Schedule Of Significant Actuarial Assumptions In Determining Funded Status Plan) (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	5.58%	4.95%
Rate of Compensation Increases	4%	4%
Interest Crediting Rates	4%	4%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	5.66%	4.98%
Trend for Next Year	9.77%	8.84%
Ultimate Trend	4.75%	4.75%
Year Ultimate Trend Reached	2033	2032

Pension and Other Postretire_12

Pension and Other Postretirement Benefits (Schedule Of Expected Payments To Participants In Pension Plan) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
2025	$ 142.6
2026	136.6
2027	130.9
2028	125.8
2029	119.4
2030-2034	528.6
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2025	36.6
2026	36.1
2027	36.1
2028	35.8
2029	35.6
2030-2034	$ 171.7

Pension and Other Postretire_13

Pension and Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 21.9	$ 20.5	$ 27.8
Interest cost	64.9	68.4	40.5
Expected return on assets	(95.3)	(94.5)	(90.8)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0.1	0.1	0.1
Recognized actuarial loss	28.6	33.7	20.3
Settlement loss	7.2	9.2	12.4
Total Net Periodic Benefits Cost	27.4	37.4	10.3
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service Cost	5	5.1	6.5
Interest cost	22	21.8	12
Expected return on assets	(16.1)	(15.1)	(16.2)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(1.8)	(2.1)	(2.2)
Recognized actuarial loss	3.2	3.3	2.6
Settlement loss	0	0	0
Total Net Periodic Benefits Cost	$ 12.3	$ 13	$ 2.7

Pension and Other Postretire_14

Pension and Other Postretirement Benefits (Schedule Of Key Assumptions That Were Used To Calculate The Net Periodic Benefits Cost) (Details)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate - service cost	5.06%	5.25%	3.08%
Discount rate - interest cost	4.88%	5.06%	2.11%
Expected Long-Term Rate of Return on Plan Assets	7.02%	7%	4.80%
Rate of Compensation Increases	4%	4%	4%
Interest Crediting Rates	4%	4%	4%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate - service cost	5.14%	5.30%	3.21%
Discount rate - interest cost	4.89%	5.07%	2.24%
Expected Long-Term Rate of Return on Plan Assets	7.06%	6.96%	5.72%

Pension and Other Postretire_15

Pension and Other Postretirement Benefits (Schedule Of Changes In Plan Assets And Projected Benefit Obligations Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Total Recognized in Other Comprehensive Income or Regulatory Asset or Liability	[1]	$ 0.3	$ (0.2)	$ (6.9)
Pension Plan
Net prior service cost/(credit)		0	0
Net actuarial (gain)/loss		(13.1)	(20.9)
Settlements		(7.2)	(9.2)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		(0.1)	(0.1)
Less: amortization of net actuarial (gain) loss		(28.6)	(33.7)
Total Recognized in Other Comprehensive Income or Regulatory Asset or Liability		(49)	(63.9)
Amount Recognized in Net Periodic Benefits Cost and Other Comprehensive Income or Regulatory Asset or Liability		(21.6)	(26.5)
Other Postretirement Benefits
Net prior service cost/(credit)		0	3.3
Net actuarial (gain)/loss		(26.4)	16
Settlements		0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		1.8	2.1
Less: amortization of net actuarial (gain) loss		(3.2)	(3.3)
Total Recognized in Other Comprehensive Income or Regulatory Asset or Liability		(27.8)	18.1
Amount Recognized in Net Periodic Benefits Cost and Other Comprehensive Income or Regulatory Asset or Liability		$ (15.5)	$ 31.1
[1] Unrecognized pension and OPEB benefit (costs), net of $0.3 million tax expense, $0.1 million tax benefit and $2.3 million tax benefit in 2024, 2023 and 2022, respectively.

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended			36 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	May 19, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for awards, shares	7,216,823
Common stock reserved for future awards, shares					10,000,000
Stock-based employee compensation expense	$ 32.1	$ 23.9	$ 19
Related tax benefits	7	7.7	3.6
Unrecognized compensation cost related to nonvested awards	$ 46.7
Weighted-average remaining requisite service period, years	1 year 9 months 18 days
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.50%
401(k) match, profit sharing and non-elective expense	$ 56.9	50.7	39.1
Excess Tax Expense - Share Based Compensation		$ 2.9	$ 0.4
Share-Based Payment Arrangement, Exercise of Option, Tax Benefit	$ 2
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	655,713
Shares nonvested	1,328,120	1,066,916		1,066,916
Shares vesting period, (years)				3 years
Granted, Weighted Average Grant Date Fair Value	$ 26.10
Restricted Stock Units (RSUs) | Share-based Payment Arrangement, Nonemployee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares nonvested	68,436
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	292,566
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	896,363	649,088	566,086
Shares nonvested	1,719,223	1,558,509		1,558,509
Shares vesting period, (years)				3 years
Granted, Weighted Average Grant Date Fair Value	$ 27.05
Performance Shares | NOEPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares granted	$ 17.4	$ 13.3
2019 Award | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			477,292
Shares nonvested	270,325
Share-based Compensation Arrangement by Share-based Payment Award, Grant Date Fair Value			$ 12.5
2020 award | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted		500,968
Shares nonvested	393,509
Share-based Compensation Arrangement by Share-based Payment Award, Grant Date Fair Value		$ 13.7
2021 award | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	655,713
Shares nonvested	592,490
Share-based Compensation Arrangement by Share-based Payment Award, Grant Date Fair Value	$ 17.1

Share-Based Compensation (Sched

Share-Based Compensation (Schedule Of Transactions Of Restricted Stock Unit) (Details) - Restricted Stock Units (RSUs) - $ / shares	12 Months Ended	36 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, Other Than Options	1,066,916
Nonvested, Weighted Average Grant Date Fair Value	$ 25.71
Granted, Other Than Options	655,713
Granted, Weighted Average Grant Date Fair Value	$ 26.10
Forfeited, Other Than Options	(167,057)
Forfeited, Weighted Average Grant Date Fair Value	$ 26.19
Vested, Other Than Options	(227,452)
Vested, Weighted Average Grant Date Fair Value	$ 22.90
Nonvested, Other Than Options	1,328,120	1,066,916
Nonvested, Weighted Average Grant Date Fair Value	$ 26.49	$ 25.71
Shares vesting period, (years)		3 years

Share-Based Compensation (Sch_2

Share-Based Compensation (Schedule Of Transactions Of Contingent Awards) (Details) - Performance Shares - $ / shares	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, Other Than Options	1,558,509
Nonvested, Weighted Average Grant Date Fair Value	$ 28.01
Granted, Other Than Options	896,363	649,088	566,086
Granted, Weighted Average Grant Date Fair Value	$ 27.05
Forfeited, Other Than Options	(189,080)
Forfeited, Weighted Average Grant Date Fair Value	$ 31.75
Vested, Other Than Options	(546,569)
Vested, Weighted Average Grant Date Fair Value	$ 21.95
Nonvested, Other Than Options	1,719,223	1,558,509
Nonvested, Weighted Average Grant Date Fair Value	$ 24.96	$ 28.01

Share-Based Compensation (Sch_3

Share-Based Compensation (Schedule of Performance Award Details) (Details) - Performance Shares - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,719,223	1,558,509
NOEPS
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 17.4	$ 13.3
NOEPS | 2022 award
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		7,400,000
NOEPS | 2023 award
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	430,670
NOEPS | 2024 award
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	619,673
Relative Total Shareholder Return | 2022 award
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	195,460
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value			$ 10.6
Relative Total Shareholder Return | 2023 award
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	143,540
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 6.9	$ 5.4
Relative Total Shareholder Return | 2024 award
Performance Share Details [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	206,524

Leases (Narrative) (Details)

Leases (Narrative) (Details)	12 Months Ended
	Dec. 31, 2024
Lessee, Lease, Description [Line Items]
Lessee, Lease Renewal Term	35 years
Lessee, Operating Lease, Renewal Term	1 year
Fleet Lease
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Minimum | Office Lease
Lessee, Lease, Description [Line Items]
Remaining Lease Term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	3 years
Maximum | Office Lease
Lessee, Lease, Description [Line Items]
Remaining Lease Term	39 years

Leases (Lease Cost) (Details)

Leases (Lease Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Finance lease cost
Amortization of right-of-use assets	$ 27.1	$ 32
Cash paid for interest on finance leases	13.5	8.6	$ 8.5
Total finance lease cost	40.6	40.6
Operating lease cost	14.7	11.3
Total lease cost	$ 55.3	$ 51.9

Leases (Right-of-Use Assets and

Leases (Right-of-Use Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Lessee, Lease, Description [Line Items]
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Net Property, Plant and Equipment	Net Property, Plant and Equipment
Finance Lease, Right-of-Use Asset	$ 222.9	$ 184.3
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Deferred charges and other	Deferred charges and other
Operating Lease, Right-of-Use Asset	$ 26.4	$ 32.9
Total leased assets	$ 249.3	$ 217.2
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long-Term Debt and Lease Obligation, Current	Long-Term Debt and Lease Obligation, Current
Finance Lease, Liability, Current	$ 22.9	$ 23.8
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current	Other Liabilities, Current
Operating Lease, Liability, Current	$ 9.1	$ 8.3
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term Debt and Lease Obligation	Long-term Debt and Lease Obligation
Finance Lease, Liability, Noncurrent	$ 223.3	$ 181.6
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Operating Lease, Liability, Noncurrent	$ 18.2	$ 25.8
Total Lease Liability	$ 273.5	$ 239.5

Leases (Lease Information) (Det

Leases (Lease Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Finance Lease, Interest Payment on Liability	$ 11.2	$ 9.3
Operating Lease, Payments	14.5	11.1
Finance Lease, Principal Payments	26.9	33.1
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	65.9	64.5
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 12.2	$ 5.6
Finance Lease, Weighted Average Remaining Lease Term	20 years 6 months	16 years 4 months 24 days
Operating Lease, Weighted Average Remaining Lease Term	5 years 7 months 6 days	6 years 8 months 12 days
Finance Lease, Weighted Average Discount Rate, Percent	5.60%	5.50%
Operating Lease, Weighted Average Discount Rate, Percent	4.50%	4.30%

Leases (Lease Maturity) (Detail

Leases (Lease Maturity) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Lease Maturity [Line Items]
Total Future Minimum Lease Payments Due, Next Twelve Months	$ 44.6
Total Future Minimum Lease Payments, Due in Two Years	34.7
Total Future Minimum Lease Payments, Due in Three Years	28.5
Total Future Minimum Lease Payments, Due in Four Years	26.1
Total Future Minimum Lease Payments, Due in Five Years	21.5
Total Future Minimum Lease Payments, Due Thereafter	304.9
Total Future Minimum Lease Payments Due	460.3
Undiscounted Excess Amount	(186.8)
Total Lease Liability	273.5	$ 239.5
Short-term Lease Liability	32
Long-term Lease Liability	241.5
Finance Leases, Future Minimum Payments Due, Next Twelve Months	34.6
Finance Leases, Future Minimum Payments Due in Two Years	29.4
Finance Leases, Future Minimum Payments Due in Three Years	24.2
Finance Leases, Future Minimum Payments Due in Four Years	23
Finance Leases, Future Minimum Payments Due in Five Years	19
Finance Leases, Future Minimum Payments Due Thereafter	299.2
Finance Lease, Liability, Payment, Due	429.4
Finance Lease, Liability, Undiscounted Excess Amount	(183.2)
Finance Lease, Liability	246.2	205.4
Finance Lease, Liability, Current	22.9	23.8
Finance Lease, Liability, Noncurrent	223.3	181.6
Operating Leases, Future Minimum Payments Due, Next Twelve Months	10
Operating Leases, Future Minimum Payments, Due in Two Years	5.3
Operating Leases, Future Minimum Payments, Due in Three Years	4.3
Operating Leases, Future Minimum Payments, Due in Four Years	3.1
Operating Leases, Future Minimum Payments, Due in Five Years	2.5
Operating Leases, Future Minimum Payments, Due Thereafter	5.7
Lessee, Operating Lease, Liability, Payments, Due	30.9
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(3.6)
Operating Lease, Liability	27.3
Operating Lease, Liability, Current	9.1	8.3
Operating Lease, Liability, Noncurrent	$ 18.2	$ 25.8

Other Commitments And Conting_3

Other Commitments And Contingencies (Narrative) (Details)						3 Months Ended	6 Months Ended	12 Months Ended
	Feb. 03, 2025 USD ($)	Jan. 15, 2025 USD ($)	Sep. 18, 2024 USD ($)	May 24, 2024 USD ($)	Mar. 18, 2024 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) Rate MW	Dec. 31, 2024 USD ($) Rate MW	Jan. 31, 2024	Dec. 31, 2023 USD ($) Rate	Jun. 17, 2023 Rate
Other Commitments And Contingencies [Line Items]
Wind power purchase agreement capacity | MW							600	600
Major Rail Operators							3	3
Line of Credit Facility, Amount Outstanding							$ 0	$ 0		$ 0
Guarantor Obligations, Current Carrying Value							$ 1,127,500,000	$ 1,127,500,000		646,100,000
Wind Power Purchase Agreement, Purchase Percentage | Rate							100%	100%
Accrual for Environmental Loss Contingencies, Gross							$ 91,800,000	$ 91,800,000		80,000,000
Other Commitment										$ 250,000,000
Asset Retirement Obligation, Period Increase (Decrease)							149,700,000
Payments to Acquire Assets, Investing Activities			$ 153,300,000	$ 114,900,000	$ 110,600,000
Contractual Obligation							$ 61,700,000	$ 61,700,000
NIPSCO Holdings II
Other Commitments And Contingencies [Line Items]
Subsidiary, Ownership Percentage, Noncontrolling Owner									4.50%
Subsidiary, Ownership Percentage, Parent | Rate											19.90%
NIPSCO Holdings II | Director
Other Commitments And Contingencies [Line Items]
Subsidiary, Ownership Percentage, Parent | Rate										17.50%
Subsequent Event
Other Commitments And Contingencies [Line Items]
Payments to Acquire Assets, Investing Activities	$ 217,600,000	$ 336,600,000
MGP Sites
Other Commitments And Contingencies [Line Items]
Number of waste disposal sites identified by program							51	51
Liability for estimated remediation costs							$ 86,400,000	$ 86,400,000		$ 73,700,000
Reasonably possible remediation costs variance from reserve							16,300,000	16,300,000
Increase (Decrease) in Other Accrued Liabilities						$ 11,200,000
Asset Retirement Obligation, Period Increase (Decrease)								$ 149,700,000
Coal Transportation | Maximum
Other Commitments And Contingencies [Line Items]
Long Term Purchase Commitment Expiration Year								2025
Pipeline Service Agreements [Member] | Maximum
Other Commitments And Contingencies [Line Items]
Long Term Purchase Commitment Expiration Year								2038
Pipeline Service Agreements [Member] | Minimum
Other Commitments And Contingencies [Line Items]
Long Term Purchase Commitment Expiration Year								2028
IT Service Agreements [Member] | Maximum
Other Commitments And Contingencies [Line Items]
Long Term Purchase Commitment Expiration Year								2029
Standby Letters of Credit
Other Commitments And Contingencies [Line Items]
Line of Credit Facility, Amount Outstanding							$ 9,400,000	$ 9,400,000		$ 9,900,000

Other Commitments and Conting_4

Other Commitments and Contingencies (Contractual Obligation, Fiscal Year Maturity Schedule) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Long-term Purchase Commitment [Line Items]
Long-term Debt, Future Minimum Payments Due	$ 13,205
Long-term Debt, Future Minimum Payments Due, Next Twelve Months	1,260
Long-term Debt, Future Minimum Payments, Due in Two Years	0
Long-term Debt, Future Minimum Payments, Due in Three Years	1,090
Long-term Debt, Future Minimum Payments, Due in Four Years	1,055
Long-term Debt, Future Minimum Payments, Due in Five Years	1,350
Long-term Debt, Future Minimum Payments, Due Thereafter	8,450
Interest Payments on Long-term Debt, Future Minimum Payments Due	8,090.3
Interest Payments on Long-term Debt, Future Minimum Payments Due, Next Twelve Months	566.2
Interest Payments on Long-term Debt, Future Minimum Payments, Due in Two Years	551.1
Interest Payments on Long-term Debt, Future Minimum Payments, Due in Three Years	531.7
Interest Payments on Long-term Debt, Future Minimum Payments, Due in Four Years	481.6
Interest Payments on Long-term Debt, Future Minimum Payments, Due in Five Years	453.9
Interest Payments on Long-term Debt, Future Minimum Payments, Due Thereafter	5,505.8
Finance Leases, Future Minimum Payments Due	429.4
Finance Leases, Future Minimum Payments Due, Next Twelve Months	34.6
Finance Leases, Future Minimum Payments Due in Two Years	29.4
Finance Leases, Future Minimum Payments Due in Three Years	24.2
Finance Leases, Future Minimum Payments Due in Four Years	23
Finance Leases, Future Minimum Payments Due in Five Years	19
Finance Leases, Future Minimum Payments Due Thereafter	299.2
Operating Leases, Future Minimum Payments Due	30.9
Operating Leases, Future Minimum Payments Due, Next Twelve Months	10
Operating Leases, Future Minimum Payments, Due in Two Years	5.3
Operating Leases, Future Minimum Payments, Due in Three Years	4.3
Operating Leases, Future Minimum Payments, Due in Four Years	3.1
Operating Leases, Future Minimum Payments, Due in Five Years	2.5
Operating Leases, Future Minimum Payments, Due Thereafter	5.7
Energy Commodity Contracts, Future Minimum Payments Due	119.7
Energy Commodity Contracts, Future Minimum Payments Due, Next Twelve Months	118.5
Energy Commodity Contracts, Future Minimum Payments, Due in Two Years	0.3
Energy Commodity Contracts, Future Minimum Payments, Due in Three Years	0.3
Energy Commodity Contracts, Future Minimum Payments, Due in Four Years	0.4
Energy Commodity Contracts, Future Minimum Payments, Due in Five Years	0.2
Energy Commodity Contracts, Future Minimum Payments, Due Thereafter	0
Service Obligations, Pipeline Service Obligations, Future Minimum Payments Due	2,694.6
Service Obligations, Pipeline Service Obligations, Future Minimum Payments Due, Next Twelve Months	685.5
Service Obligations, Pipeline Service Obligations, Future Minimum Payments, Due in Two Years	631.2
Service Obligations, Pipeline Service Obligations, Future Minimum Payments, Due in Three Years	609.2
Service Obligations, Pipeline Service Obligations, Future Minimum Payments, Due in Four Years	373.2
Service Obligations, Pipeline Service Obligations, Future Minimum Payments, Due in Five Years	245.2
Service Obligations, Pipeline Service Obligations, Future Minimum Payments, Due Thereafter	150.3
Service Obligations, IT Service Obligations, Future Minimum Payments Due	120.7
Service Obligations, IT Service Obligations, Future Minimum Payments Due, Next Twelve Months	73.9
Service Obligations, IT Service Obligations, Future Minimum Payments, Due in Two Years	30.3
Service Obligations, IT Service Obligations, Future Minimum Payments, Due in Three Years	11.4
Service Obligations, IT Service Obligations, Future Minimum Payments, Due in Four Years	5.1
Service Obligations, IT Service Obligations, Future Minimum Payments, Due in Five Years	0
Service Obligations, IT Service Obligations, Future Minimum Payments, Due Thereafter	0
Plant equipment purchase obligations, Future Minimum Payments, Due Thereafter	0
Plant equipment purchase obligations, Future Minimum Payments, Due in Five Years	0
Plant equipment purchase obligations, Future Minimum Payments, Due in Four Years	3.8
Plant equipment purchase obligations, Future Minimum Payments, Due in Three Years	4.3
Plant equipment purchase obligations, Future Minimum Payments, Due in Two Years	24.9
Plant equipment purchase obligations, Future Minimum Payments Due, Next Twelve Months	140.5
Plant equipment purchase obligations, Future Minimum Payments Due	173.5
Other Liabilities, Future Minimum Payments Due	336
Other Liabilities, Future Minimum Payments Due, Next Twelve Months	287
Other Liabilities, Future Minimum Payments, Due in Two Years	7.9
Other Liabilities, Future Minimum Payments, Due in Three Years	7.7
Other Liabilities, Future Minimum Payments, Due in Four Years	7.6
Other Liabilities, Future Minimum Payments, Due in Five Years	7.7
Other Liabilities, Future Minimum Payments, Due Thereafter	18.1
Total Future Contractual Obligations Due	25,200.1
Total Future Contractual Obligations Due, Next Twelve Months	3,176.2
Total Future Contractual Obligations, Due in Two Years	1,280.4
Total Future Contractual Obligations, Due in Three Years	2,283.1
Total Future Contractual Obligations, Due in Four Years	1,952.8
Total Future Contractual Obligations, Due in Five Years	2,078.5
Total Future Contractual Obligations, Due Thereafter	14,429.1
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	(95.5)	$ (81.1)
Finance Lease, Liability, Undiscounted Excess Amount	(183.2)
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	$ (3.6)

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	$ 0.3	$ 1.2	$ 87.1
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	2.9	2.3	2.6
Net current-period other comprehensive income (loss)	3.2	3.5	89.7
Accumulated other comprehensive loss	(30.4)	(33.6)	(37.1)	$ (126.8)
Gains and Losses on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1.5	3.1	(13.7)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1.8	0.8	0.4
Net current-period other comprehensive income (loss)	3.3	3.9	(13.3)
Accumulated other comprehensive loss	(4)	(7.3)	(11.2)	2.1
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	(0.5)	109.7
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(0.4)	0.3	0.2
Net current-period other comprehensive income (loss)		(0.2)	109.9
Accumulated other comprehensive loss	(13.2)	(12.8)	(12.6)	(122.5)
Pension and OPEB Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1.2)	(1.4)	(8.9)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1.5	1.2	2
Net current-period other comprehensive income (loss)	0.3	(0.2)	(6.9)
Accumulated other comprehensive loss	$ (13.2)	$ (13.5)	$ (13.3)	$ (6.4)

Business Segment Information (N

Business Segment Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2024 Segment
Goodwill [Line Items]
Number of Reportable Segments	2

Business Segment Information (S

Business Segment Information (Schedule Of Operating Income Derived From Revenues And Expenses By Segment) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating Revenues	$ 5,455.1	$ 5,455.1	$ 5,505.4	$ 5,850.6
Cost of energy		1,132.2	1,533.3	2,110.5
O&M		1,515.2	1,494.9	1,489.4
Depreciation and amortization		1,043.2	908.2	820.8
Total other taxes		300	270.6	268.3
Operating Income		1,455.5	1,295.5	1,265.8
Capital Expenditures		3,692.5	2,690.7	2,298
Consolidated Assets	31,788.1	31,788.1	31,077.2	26,736.6
Total Reportable Segments
Segment Reporting Information [Line Items]
Operating Revenues		5,468	5,517.7	5,851.5
Cost of energy		1,132.2	1,533.3	2,110.5
O&M		1,598.9	1,580	1,531.7
Depreciation and amortization		999.4	865.5	778.8
Total other taxes		282.9	256.7	256.3
Other segment items		6.1	2.2	(103.9)
Operating Income		1,448.5	1,280	1,278.1
Capital Expenditures		3,461.4	2,454.4	2,256.8
Consolidated Assets	30,593	30,593	27,627.1	24,819.3
Total Reportable Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Operating Revenues		5,454.2	5,504.6	5,838.1
Total Reportable Segments | Intersegment Revenue
Segment Reporting Information [Line Items]
Operating Revenues		13.8	13.1	13.4
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenues		581.9	504.6	477.5
Operating Income		7	15.5	(12.3)
Capital Expenditures		231.1	236.3	41.2
Consolidated Assets	1,195.1	1,195.1	3,450.1	1,917.3
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues		(594.8)	(516.9)	(478.4)
Columbia Operations
Segment Reporting Information [Line Items]
Operating Revenues		2,703.2	2,733.9	2,951.9
Columbia Operations | Total Reportable Segments
Segment Reporting Information [Line Items]
Operating Revenues		2,716	2,746.1	2,964.4
Cost of energy		514.7	645	978.4
O&M		837.5	792.3	791.3
Depreciation and amortization		409.1	371.7	329.4
Total other taxes		218.6	198.8	184.2
Other segment items		7.4	0	(103.9)
Operating Income		728.7	738.3	785
Capital Expenditures		(1,209)	(1,159.6)	(1,237.9)
Consolidated Assets	14,769.5	14,769.5	13,664.5	13,059.4
Columbia Operations | Total Reportable Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Operating Revenues		2,703.2	2,733.9	2,951.9
Columbia Operations | Total Reportable Segments | Intersegment Revenue
Segment Reporting Information [Line Items]
Operating Revenues		12.8	12.2	12.5
NIPSCO Operations
Segment Reporting Information [Line Items]
Operating Revenues	2,751
NIPSCO Operations | Total Reportable Segments
Segment Reporting Information [Line Items]
Operating Revenues		2,752	2,771.6	2,887.1
Cost of energy		617.5	888.3	1,132.1
O&M		761.4	787.7	740.4
Depreciation and amortization		590.3	493.8	449.4
Total other taxes		64.3	57.9	72.1
Other segment items		(1.3)	2.2	0
Operating Income		719.8	541.7	493.1
Capital Expenditures		(2,252.4)	(1,294.8)	(1,018.9)
Consolidated Assets	$ 15,823.5	15,823.5	13,962.6	11,759.9
NIPSCO Operations | Total Reportable Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Operating Revenues		2,751	2,770.7	2,886.2
NIPSCO Operations | Total Reportable Segments | Intersegment Revenue
Segment Reporting Information [Line Items]
Operating Revenues		$ 1	$ 0.9	$ 0.9

Other, Net (Schedule Of Other N

Other, Net (Schedule Of Other Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Nonoperating Income [Line Items]
Interest income	$ 10.4	$ 9	$ 4.3
AFUDC equity	75.1	25.2	15.1
Charitable Contributions	(5.4)	(1.8)	(4.4)
Pension and Other Postretirement Non Service Cost	(13.5)	(24)	27.6
Other Nonoperating Expense	(2.1)
Miscellaneous		(0.4)	(0.4)
Total Other, net	64.5	8	52.2
Interest Rate Swap Settled
Other Nonoperating Income [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 0	$ 0	$ 10

Interest Expense, Net (Details)

Interest Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Interest Expense, Operating and Nonoperating [Abstract]
Interest on long-term debt	$ 506.2	$ 404.1	$ 344.5
Interest on short-term borrowings	43.2	108.9	22.7
Debt discount/cost amortization	13.8	13.5	11.7
Accounts receivable securitization fees	1.5	2.7	2.5
Allowance for borrowed funds used and interest capitalized during construction	(40.1)	(25.3)	(6.7)
Debt-based post-in-service carrying charges	(26.4)	(30.7)	(21.1)
Other	19	16.4	8
Total Interest Expense, net	$ 517.2	$ 489.6	$ 361.6

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Non-cash transactions:
Capital expenditures included in current liabilities	$ 367	$ 315	$ 275.1
Assets acquired under a finance lease		64.5	19.3
Assets acquired under an operating lease		5.6	8.8
Assets recorded for asset retirement obligations	277.4	61.1	6.3
Purchase Contract Liability	0	0	65
Schedule of interest and income taxes paid:
Cash paid for interest on debt, net of interest capitalized amounts	468.2	433.9	343.8
Cash paid for interest on finance leases	13.5	8.6	8.5
Cash paid for income taxes, net of refunds	4.3	9.4	$ 7.2
Finance Lease, Interest Payment on Liability	$ 11.2	$ 9.3

Valuation and Qualifying Acco_2

Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reserve For Accounts Receivable [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 22.9	$ 23.9	$ 23.5
Valuation Allowances and Reserves, Charged to Cost and Expense	23.2	23.4	20.6
Valuation Allowances and Reserves, Charged to Other Accounts	(32.3)	(36.6)	(36.4)
Deductions for Purposes for which Reserves were Created	54.7	61	56.6
Ending Balance	23.7	22.9	23.9
Reserve For Other Investments [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	1.3	1	2.3
Valuation Allowances and Reserves, Charged to Cost and Expense	0	0	0
Valuation Allowances and Reserves, Charged to Other Accounts			(1.3)
Deductions for Purposes for which Reserves were Created	0	0	0
Ending Balance	1.1	1.3	$ 1
Reserve for Deferred Charges and Other
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Charged to Other Accounts	$ (0.2)	$ (0.3)