NiSource (NI) 10-Q 5 May 21 2021 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 26, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		392,217,046
Entity Central Index Key	0001111711
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Series A Corporate Units
Document Information [Line Items]
Title of 12(b) Security	Series A Corporate Units
Trading Symbol	NIMC
Security Exchange Name	NYSE
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
Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B
Trading Symbol	NI PR B
Security Exchange Name	NYSE

Statements Of Consolidated Inco

Statements Of Consolidated Income (Loss) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Revenues
Customer revenues	$ 1,506.5	$ 1,525.9
Other revenues	39.1	79.6
Total Operating Revenues	1,545.6	1,605.5
Operating Expenses
Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization	476.8	462.4
Operation and maintenance	361.5	444.6
Depreciation and amortization	185	184.3
Loss on sale of assets, net	8.1	280.1
Other taxes	81	85.9
Operating Costs and Expenses	1,112.4	1,457.3
Operating Income	433.2	148.2
Other Income (Deductions)
Interest expense, net	(84.6)	(92.9)
Other, net	10.5	5.4
Total Other Deductions, Net	(74.1)	(87.5)
Income before Income Taxes	359.1	60.7
Income Taxes	62.6	(14.9)
Net Income	296.5	75.6
Net income attributable to noncontrolling interest	1	0
Net Income attributable to NiSource	295.5	75.6
Preferred dividends	(13.8)	(13.8)
Net Income Available to Common Shareholders	$ 281.7	$ 61.8
Earnings Per Share
Basic Earnings Per Share	$ 0.72	$ 0.16
Diluted Earnings Per Share	$ 0.72	$ 0.16
Basic Average Common Shares Outstanding	392,657	383,062
Diluted Average Common Shares	393,912	384,114

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Net Income		$ 296.5	$ 75.6
Other comprehensive income (loss):
Net unrealized loss on available-for-sale securities	[1]	(2.5)	(5.4)
Net unrealized gain (loss) on cash flow hedges	[2]	84.6	(133.3)
Unrecognized pension and OPEB benefit (costs)	[3]	(0.9)	0.7
Total other comprehensive income (loss)		81.2	(138)
Comprehensive Income (Loss)		$ 377.7	$ (62.4)
[1]	Net unrealized loss on available-for-sale debt securities, net of $0.7 million and $1.4 million tax benefit in the first quarter of 2021 and 2020, respectively.
[2]	Net unrealized gain (loss) on cash flow hedges, net of $28.0 million tax expense and $44.1 million tax benefit in the first quarter of 2021 and 2020, respectively.
[3]	Unrecognized pension and OPEB benefit (costs), net of $0.9 million tax expense and $0.3 million tax benefit in the first quarter of 2021 and 2020, respectively.

Statements of Consolidated Co_2

Statements of Consolidated Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	$ (0.7)	$ (1.4)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	28	(44.1)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	$ (0.9)	$ 0.3

Statements of Consolidated Bala

Statements of Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
Plant		$ 24,524.7	$ 24,179.9
Accumulated depreciation and amortization		(7,688)	(7,560.4)
Net Property, Plant and Equipment	[1]	16,836.7	16,619.5
Investments and Other Assets
Available-for-sale debt securities (amortized cost of $163.8 and $163.9, allowance for credit losses of $0.3 and $0.5, respectively)		167.9	170.9
Other investments		81.5	81.1
Total Investments and Other Assets		249.4	252
Current Assets
Cash and cash equivalents		89.1	116.5
Restricted Cash		7.6	9.1
Accounts receivable		848.4	843.6
Allowance for credit losses		(53.9)	(52.3)
Accounts receivable, net		794.5	791.3
Gas inventory		48.1	191.2
Materials and supplies, at average cost		145.6	141.5
Electric production fuel, at average cost		52.5	68.4
Exchange gas receivable		53.7	34.1
Regulatory assets		188.9	135.7
Deferred property taxes		104.2	85.6
Prepayments and other		109.3	86
Total Current Assets	[1]	1,593.5	1,659.4
Other Assets
Regulatory assets		1,791.3	1,794.8
Goodwill		1,485.9	1,485.9
Deferred charges and other		237.7	228.9
Total Other Assets		3,514.9	3,509.6
Total Assets		22,194.5	22,040.5
Stockholders' Equity
Common stock - $0.01 par value, 600,000,000 shares authorized; 392,129,866 and 391,760,051 shares outstanding, respectively		3.9	3.9
Preferred stock - $0.01 par value, 20,000,000 shares authorized; 440,000 shares outstanding		880	880
Treasury stock		(99.9)	(99.9)
Additional paid-in capital		6,892.9	6,890.1
Retained deficit		(1,669.8)	(1,765.2)
Accumulated other comprehensive loss		(75.5)	(156.7)
Total NiSource Stockholders’ Equity		5,931.6	5,752.2
Noncontrolling interest in consolidated subsidiaries		94.1	85.6
Total Stockholders' Equity		6,025.7	5,837.8
Long-term debt, excluding amounts due within one year		9,202.3	9,219.8
Total Capitalization		15,228	15,057.6
Current Liabilities
Current portion of long-term debt		44.4	23.3
Short-term borrowings		520	503
Accounts payable		554.9	589
Dividends payable - common stock		86.3	0
Dividends payable - preferred stock		19.4	0
Customer deposits and credits		146.7	243.3
Taxes accrued		301.5	244.1
Interest accrued		94.6	104.7
Exchange gas payable		25.5	48.5
Regulatory liabilities		169.6	161.3
Accrued compensation and employee benefits		131.2	141.8
Other accruals		164.7	220.4
Total Current Liabilities		2,258.8	2,279.4
Other Liabilities
Deferred income taxes		1,573.6	1,470.6
Accrued liability for postretirement and postemployment benefits		328.9	336.1
Regulatory liabilities		1,881	1,904.2
Asset retirement obligations		479.7	477.1
Other noncurrent liabilities		444.5	515.5
Total Other Liabilities		4,707.7	4,703.5
Total Capitalization and Liabilities		$ 22,194.5	$ 22,040.5
[1]	(1) Includes $174.2 million and $175.6 million of net property, plant and equipment assets and $4.2 million and $1.7 million of current assets of a consolidated VIE as of March 31, 2021 and December 31, 2020 that may be used only to settle obligations of the consolidated VIE. Refer to Note 15 "Variable Interest Entities" for additional information.

Statements of Consolidated Ba_2

Statements of Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Amortized Cost	$ 163.8	$ 163.9
Allowance for Credit Loss	$ 0.3	$ 0.5
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	600,000,000	600,000,000
Common Stock, Shares, Outstanding	392,129,866	391,760,051
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	440,000	440,000

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net Income	$ 296.5	$ 75.6
Adjustments to Reconcile Net Income to Net Cash from Operating Activities:
Depreciation and amortization	185	184.3
Deferred income taxes and investment tax credits	55.2	(19.9)
Loss on sale of assets	8.1	280.2
Other adjustments	3.5	7.9
Changes in Assets and Liabilities:
Components of working capital	(89.3)	(147.1)
Regulatory assets/liabilities	8.4	12.9
Deferred charges and other noncurrent assets	(10.7)	(12.1)
Other noncurrent liabilities	(8.4)	(11.9)
Net Cash Flows from Operating Activities	448.3	369.9
Investing Activities
Capital expenditures	(367)	(452.1)
Cost of removal	(26.9)	(34.5)
Purchases of available-for-sale securities	(16.6)	(43.5)
Sales of available-for-sale securities	16.9	45.4
Payment to renewable generation asset developer	(7.4)	0
Other investing activities	(0.8)	0.1
Net Cash Flows used for Investing Activities	(401.8)	(484.6)
Financing Activities
Repayments of long-term debt and finance lease obligations	(5.9)	(4.1)
Issuance of short-term debt (maturity greater than 90 days)	0	500
Change in short-term borrowings, net (maturity ≤ 90 days)	17	(226.8)
Issuance of common stock, net of issuance costs	2.8	3.7
Equity costs, premiums and other debt related costs	(2.5)	(5.1)
Contributions from non-controlling interest, net of issuance costs	7.5	0
Dividends paid - common stock	(86.2)	(80.3)
Dividends paid - preferred stock	(8.1)	(8.1)
Net Cash Flows (used for) from Financing Activities	(75.4)	179.3
Change in cash, cash equivalents and restricted cash	(28.9)	64.6
Cash, cash equivalents and restricted cash at beginning of period	125.6	148.4
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 96.7	$ 213

Statements Of Consolidated Ca_2

Statements Of Consolidated Cash Flows (Supplemental Disclosures of Cash Flow Information) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Capital expenditures included in current liabilities	$ 155.6	$ 150.5
Dividends declared but not paid	105.7	99.8
Assets recorded for asset retirement obligations	0	69.8
Obligation to developer at formation of joint venture	$ 6	$ 0

Statements Of Consolidated Equi

Statements Of Consolidated Equity - USD ($) $ in Millions	Total	Common Stock	Preferred Stock	[1]	Treasury Stock	Additional Paid-in Capital	Retained Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Beginning balance at Dec. 31, 2019	$ 5,986.7	$ 3.8	$ 880		$ (99.9)	$ 6,666.2	$ (1,370.8)	$ (92.6)	$ 0
Comprehensive Income:
Net Income	75.6	0	0		0	0	75.6	0	0
Other comprehensive income (loss), net of tax	(138)	0	0		0	0	0	(138)	0
Dividends:
Common stock	(160.7)	0	0		0	0	(160.7)	0	0
Preferred stock	(27.5)	0	0		0	0	(27.5)	0	0
Stock Issuances:
Employee stock purchase plan	1.3	0	0		0	1.3	0	0	0
Long-term incentive plan	(0.5)	0	0		0	(0.5)	0	0	0
401(k) and profit sharing	4.5	0	0		0	4.5	0	0	0
Ending balance at Mar. 31, 2020	5,741.4	3.8	880		(99.9)	6,671.5	(1,483.4)	(230.6)	0
Beginning balance at Dec. 31, 2020	5,837.8	3.9	880		(99.9)	6,890.1	(1,765.2)	(156.7)	85.6
Comprehensive Income:
Net Income	296.5	0	0		0	0	295.5	0	1
Other comprehensive income (loss), net of tax	81.2	0	0		0	0	0	81.2	0
Dividends:
Common stock	(172.6)	0	0		0	0	(172.6)	0	0
Preferred stock	(27.5)	0	0		0	0	(27.5)	0	0
Contribution from noncontrolling interest	7.5	0	0		0	0	0	0	7.5
Stock Issuances:
Employee stock purchase plan	1.3	0	0		0	1.3	0	0	0
Long-term incentive plan	(0.5)	0	0		0	(0.5)	0	0	0
401(k) and profit sharing	2.3	0	0		0	2.3	0	0	0
ATM program	(0.3)	0	0		0	(0.3)	0	0	0
Ending balance at Mar. 31, 2021	$ 6,025.7	$ 3.9	$ 880		$ (99.9)	$ 6,892.9	$ (1,669.8)	$ (75.5)	$ 94.1
[1]	(1) Series A and Series B shares have an aggregate liquidation preference of $400M and $500M, respectively. See Note 5, "Equity" for additional information.

Statements of Consolidated Eq_2

Statements of Consolidated Equity (Shares) - shares shares in Thousands	Total	Preferred Stock	Common Stock	Treasury Stock
Beginning balance at Dec. 31, 2019	382,136	440	386,099	(3,963)
Issued:
Employee stock purchase plan	46	0	46	0
Long-term incentive plan	347	0	347	0
401(k) and profit sharing	165	0	165	0
Ending balance at Mar. 31, 2020	382,694	440	386,657	(3,963)
Beginning balance at Dec. 31, 2020	391,760	440	395,723	(3,963)
Issued:
Employee stock purchase plan	55	0	55	0
Long-term incentive plan	212	0	212	0
401(k) and profit sharing	103	0	103	0
Ending balance at Mar. 31, 2021	392,130	440	396,093	(3,963)

Statements Of Consolidated Eq_3

Statements Of Consolidated Equity (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Common Stock, Dividends, Per Share, Declared	$ 0.44	$ 0.42
Series A Preferred Stock
Preferred Stock, Liquidation Preference, Value	$ 400	$ 400
Series B Preferred Stock
Preferred Stock, Liquidation Preference, Value	$ 500	$ 500

Basis of Accounting Presentatio

Basis of Accounting Presentation	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting Presentation	Basis of Accounting Presentation Our accompanying Condensed Consolidated Financial Statements (unaudited) reflect all normal recurring adjustments that are necessary, in the opinion of management, to present fairly the results of operations in accordance with GAAP in the United States of America. The accompanying 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. The accompanying financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020. Income for interim periods may not be indicative of results for the calendar year due to weather variations and other factors. The Condensed Consolidated Financial Statements (unaudited) have been prepared pursuant to the rules and regulations of the SEC. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations, although we believe that the disclosures made in this Quarterly Report on Form 10-Q are adequate to make the information herein not misleading.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Issued Accounting Pronouncements We are currently evaluating the impact of certain ASUs on our Condensed Consolidated Financial Statements (unaudited) and Notes to Condensed Consolidated Financial Statements (unaudited), which are described below: Standard Description Effective Date Effect on the financial statements or other significant matters ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Statement This pronouncement provides Upon issuance on We continue to evaluate the temporary expedients and options available under this guidance, and the effects of this pronouncement on our Condensed Consolidated Financial Statements (unaudited) and Notes to Condensed Consolidated Financial Statements (unaudited). We are currently identifying and evaluating contracts that may be impacted. As of March 31, 2021, we have not applied any expedients and options available under this ASU. ASU 2021-01, Reference Rate Reform (Topic 848): Scope ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivative and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity This pronouncement simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity's own equity. Specifically, the ASU "simplifies accounting for convertible instruments by removing major separation models required under current GAAP." In addition, the ASU "removes certain settlement conditions that are required for equity contracts to qualify for it" and "simplifies the diluted earnings per share (EPS) calculations in certain areas." Annual period beginning after December 15, 2021, and interim periods within those fiscal years. We continue to evaluate the effects of this pronouncement on our Condensed Consolidated Financial Statements (unaudited) and Notes to Condensed Consolidated Financial Statements (unaudited) as it pertains to any relevant future activity. We expect to adopt this ASU on its effective date. Recently Adopted Accounting Pronouncements Standard Adoption ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes This pronouncement simplifies the accounting for income taxes by eliminating certain exceptions to the general principles in ASC 740, income taxes. It also improves consistency of application for other areas of the guidance by clarifying and amending existing guidance. We adopted the amendments of this pronouncement as of January 1, 2021 with no material impact to the Condensed Consolidated Financial Statements (unaudited).

Revenue Recognition

Revenue Recognition	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	Revenue Recognition Revenue Disaggregation and Reconciliation. We disaggregate revenue from contracts with customers based upon reportable segment, as well as by customer class. As our revenues are primarily earned over a period of time and we do not earn a material amount of revenues at a point in time, revenues are not disaggregated as such below. The Gas Distribution Operations segment provides natural gas service and transportation for residential, commercial and industrial customers in Ohio, Pennsylvania, Virginia, Kentucky, Maryland, and Indiana. We completed the sale of the Massachusetts Business on October 9, 2020. The Electric Operations segment provides electric service in 20 counties in the northern part of Indiana. The tables below reconcile revenue disaggregation by customer class to segment revenue, as well as to revenues reflected on the Condensed Statements of Consolidated Income (unaudited) for the three months ended March 31, 2021 and March 31, 2020: Three Months Ended March 31, 2021 (in millions) Gas Distribution Operations Electric Operations Corporate and Other (2) Total Customer Revenues (1) Residential $ 773.5 $ 129.2 $ — $ 902.7 Commercial 271.4 122.9 — 394.3 Industrial 57.9 122.9 — 180.8 Off-system 14.4 — — 14.4 Miscellaneous 9.9 4.2 0.2 14.3 Total Customer Revenues $ 1,127.1 $ 379.2 $ 0.2 $ 1,506.5 Other Revenues 8.7 23.3 7.1 39.1 Total Operating Revenues $ 1,135.8 $ 402.5 $ 7.3 $ 1,545.6 (1) Customer revenue amounts exclude intersegment revenues. See Note 20, "Business Segment Information," for discussion of intersegment revenues. (2) Other revenues related to the Transition Services Agreement entered into in connection with the sale of the Massachusetts Business. Three Months Ended March 31, 2020 (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Customer Revenues (1) Residential $ 796.5 $ 119.2 $ — $ 915.7 Commercial 269.4 120.2 — 389.6 Industrial 74.2 109.1 — 183.3 Off-system 18.7 — — 18.7 Miscellaneous 12.5 5.9 0.2 18.6 Total Customer Revenues $ 1,171.3 $ 354.4 $ 0.2 $ 1,525.9 Other Revenues 56.7 22.9 — 79.6 Total Operating Revenues $ 1,228.0 $ 377.3 $ 0.2 $ 1,605.5 (1) Customer revenue amounts exclude intersegment revenues. See Note 20, "Business Segment Information," for discussion of intersegment revenues. Customer Accounts Receivable. Accounts receivable on our Condensed Consolidated Balance Sheets (unaudited) 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 the 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. The opening and closing balances of customer receivables for the three months ended March 31, 2021 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, 2020 $ 400.0 $ 327.2 Balance as of March 31, 2021 507.4 244.3 Increase (Decrease) $ 107.4 $ (82.9) 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. In connection with the COVID-19 pandemic, certain state regulatory commissions instituted regulatory moratoriums that impacted our ability to pursue our standard credit risk mitigation practices. Following the issuance of these moratoriums, certain of our regulated operations have been authorized to recognize a regulatory asset for bad debt costs above levels currently in rates. We have reinstated our common credit mitigation practices where moratoriums have expired (see Note 8, "Regulatory Matters," for additional information on regulatory moratoriums and regulatory assets). 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. Relevant and reliable internal and external inputs used in the model include, but are not limited to, energy consumption trends, revenue projections, actual charge-offs data, recoveries data, shut-off orders executed data, and final bill data. We continuously evaluate available reasonable and supportable information relevant to assessing collectability of current and future receivables. We evaluate creditworthiness of specific customers periodically or when required by 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; these include, but are 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 using an allowance for credit losses account. When deemed to be uncollectible, customer accounts are written-off. A rollforward of our allowance for credit losses for the three months ended March 31, 2021 are presented in the table below: Three Months Ended March 31, 2021 ( in millions ) Gas Distribution Operations Electric Operations Corporate and Other Total Beginning balance $ 41.8 $ 9.7 $ 0.8 $ 52.3 Current period provisions 5.9 2.9 — 8.8 Write-offs charged against allowance (9.0) (2.4) — (11.4) Recoveries of amounts previously written off 4.1 0.1 — 4.2 Ending balance of the allowance for credit losses $ 42.8 $ 10.3 $ 0.8 $ 53.9

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic EPS is computed by dividing net income available to common shareholders by the weighted-average number of shares of common stock outstanding for the period. The weighted-average shares outstanding for diluted EPS includes the incremental effects of the various long-term incentive compensation plans and an ATM forward agreement under the Treasury Stock Method when the impact would be dilutive (See Note 5 "Equity"). The computation of diluted average common shares is as follows: Three Months Ended March 31, (in thousands) 2021 2020 Basic average common shares outstanding 392,657 383,062 Dilutive potential common shares: Shares contingently issuable under employee stock plans 630 845 Shares restricted under employee stock plans 288 207 Forward Agreement 337 — Diluted Average Common Shares 393,912 384,114

Equity

Equity	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Equity	Equity ATM Program and Forward Sale Agreement. On February 22, 2021, we entered into six separate equity distribution agreements pursuant to which we are able to sell up to an aggregate of $750.0 million of our common stock. On February 23, 2021, under the ATM program, we executed a forward agreement, which allows us to issue a fixed number of shares at a price to be settled in the future. From February 24, 2021 to March 17, 2021, we borrowed 6,672,740 shares from third parties, which the dealer sold at a weighted average price of $22.48 per share. We may settle this agreement in shares, cash, or net shares by December 15, 2021. Had we settled all the shares under the forward agreement at March 31, 2021, we would have received approximately $148.5 million, based on a net price of $22.25 per share. As of March 31, 2021, the ATM program (including the impacts of the forward sale agreement discussed above) had approximately $600.0 million of equity available for issuance. The program expires on December 31, 2023. Preferred Stock . As of March 31, 2021, we had 20,000,000 shares of preferred stock authorized for issuance, of which 440,000 shares of preferred stock in the aggregate for all series were outstanding. The following table displays preferred dividends declared for the period by outstanding series of shares: Three Months Ended March December 31, 2021 2020 2021 2020 (in millions except shares and per share amounts) Liquidation Preference Per Share Shares Dividends Declared Per Share Outstanding 5.650% Series A $ 1,000.00 400,000 28.25 28.25 $ 393.9 $ 393.9 6.500% Series B $ 25,000.00 20,000 812.50 812.50 $ 486.1 $ 486.1 In addition, 20,000 shares of Series B–1 Preferred Stock, par value $0.01 per share, were outstanding as of March 31, 2021. Holders of Series B–1 Preferred Stock are not entitled to receive dividend payments and have no conversion rights. The Series B–1 Preferred Stock is paired with the Series B Preferred Stock and may not be transferred, redeemed or repurchased except in connection with the simultaneous transfer, redemption or repurchase of the underlying Series B Preferred Stock. As of March 31, 2021 and 2020, Series A Preferred Stock had $6.7 million of cumulative preferred dividends in arrears, or $16.63 per share, and Series B Preferred Stock had $1.4 million of cumulative preferred dividends in arrears, or $72.23 per share.

Gas in Storage

Gas in Storage	3 Months Ended
	Mar. 31, 2021
Gas in Storage [Abstract]
Gas in Storage	Gas in StorageWe use both the LIFO inventory methodology and the weighted-average cost methodology to value natural gas in storage. Gas Distribution Operations prices natural gas storage injections at the average of the costs of natural gas supply purchased during the year. For interim periods, the difference between current projected replacement cost and the LIFO cost for quantities of gas temporarily withdrawn from storage is recorded as a temporary LIFO liquidation credit or debit within the Condensed Consolidated Balance Sheets (unaudited). Due to seasonality requirements, we expect interim variances in LIFO layers to be replenished by year end. We had a temporary LIFO liquidation debit of $22.3 million and zero as of March 31, 2021 and December 31, 2020, respectively, for certain gas distribution companies recorded within “Prepayments and other,” on the Condensed Consolidated Balance Sheets (unaudited).

Property, Plant, and Equipment

Property, Plant, and Equipment	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Property, Plant and Equipment In 2020, the MISO approved NIPSCO's plan to retire the R.M. Schahfer Generating Station in 2023. The December 2019 NIPSCO electric rate case order included approval to create a regulatory asset upon the retirement of the R.M. Schahfer Generating Station. The order allows for the recovery of and on the net book value of the station by the end of 2032. In connection with the MISO's approval of NIPSCO's planned retirement of the R.M. Schahfer Generating Station, we recorded plant retirement-related charges during 2020 comprised of write downs of certain capital projects that have been cancelled and materials and supplies inventory balances deemed obsolete due to the planned retirement. As more information becomes available, the retirement date of the R.M. Schahfer Generating Station will be finalized, and additional plant retirement-related charges may be incurred. An immaterial amount of plant retirement-related charges were included within "Operation and maintenance" in the Condensed Statement of Consolidated Income (unaudited) during the three months ended March 31, 2021. On March 11, 2021, NIPSCO submitted modified Attachment Y Notices to MISO requesting an updated retirement date for two of the four coal fired units at R.M. Schahfer Generating Station. The two units are now expected to be retired by the end of 2021, with the remaining two units still scheduled to be retired in 2023. At retirement, the net book value of the retired units will be reclassified from "Net Property, Plant and Equipment", to current and long-term “Regulatory Assets.” The total net book value of R.M. Schahfer Generating Station's coal units and other associated plant was $861.6 million at March 31, 2021. On April 28, 2021, in response to a Motion filed by certain parties in NIPSCO's quarterly FAC proceeding, the IURC created a sub-docket proceeding in order to receive additional information related to the planned retirements of Units 14 and 15 by the end of 2021 and any resulting cost impacts to customers. NIPSCO does not anticipate that the sub-docket proceeding will impact the planned timing of end of year 2021 for the unit retirements.

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2021
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters COVID-19 Regulatory Filings In response to COVID-19, we received approvals or directives from the regulatory commissions in the states in which we operate. The ongoing impacts of these approvals or directives are described in the table below: Jurisdiction Moratorium in Place? Regulatory Asset balance as of March 31, 2021 (in millions) Deferred COVID-19 Costs Columbia of Ohio No $ 2.0 Incremental operation and maintenance expenses NIPSCO No $ 12.0 Incremental bad debt expense and the costs to implement the requirements of the COVID-19 related order Columbia of Pennsylvania No $ 7.1 Incremental bad debt expense incurred since March 13, 2020 above levels currently in rates Columbia of Virginia Yes $ 0.1 Incremental incurred costs, subject to an earnings test review Columbia of Maryland No $ 1.1 Incremental costs (including incremental bad debt expense) incurred to ensure that customers have essential utility service during the state of emergency in Maryland. Such incremental costs must be offset by any benefit received in connection with the pandemic On March 11, 2021, the Pennsylvania PUC adopted an order, which lifted its prior pandemic-related moratorium on service terminations for non-payments of utility bills beginning April 1, 2021. Pursuant to that order, Pennsylvania utilities are required to offer payment plans on billing arrearages, with the length of such payment plans depending on customers' income levels. The longest such payment plan would be a minimum of five years for residential customers with incomes below 250% of the Federal Poverty Level.

Risk Management Activities

Risk Management Activities	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities	Risk Management ActivitiesWe are exposed to certain risks relating 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 lower our cost of debt capital, manage our interest rate exposure and limit volatility in the price of natural gas. Risk management assets and liabilities on our derivatives are presented on the Condensed Consolidated Balance Sheets (unaudited) as shown below: (in millions) March 31, 2021 December 31, 2020 Risk Management Assets - Current (1) Interest rate risk programs $ — $ — Commodity price risk programs 1.0 10.4 Total $ 1.0 $ 10.4 Risk Management Assets - Noncurrent (2) Interest rate risk programs $ — $ — Commodity price risk programs 3.2 2.8 Total $ 3.2 $ 2.8 Risk Management Liabilities - Current (3) Interest rate risk programs $ 17.1 $ 70.9 Commodity price risk programs 5.0 7.3 Total $ 22.1 $ 78.2 Risk Management Liabilities - Noncurrent (4) Interest rate risk programs $ 40.6 $ 99.5 Commodity price risk programs 38.3 45.1 Total $ 78.9 $ 144.6 (1) Presented in "Prepayments and other" on the Condensed Consolidated Balance Sheets (unaudited). (2) Presented in "Deferred charges and other" on the Condensed Consolidated Balance Sheets (unaudited). (3) Presented in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited). (4) Presented in "Other noncurrent liabilities" on the Condensed Consolidated Balance Sheets (unaudited). Commodity 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 to certain customers 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. NIPSCO received IURC approval to lock in a fixed price for its natural gas customers using long-term forward purchase instruments. The term of these instruments may range from five Interest Rate Risk Management As of March 31, 2021, we have two forward-starting interest rate swaps with an aggregate notional value totaling $500.0 million to hedge the variability in cash flows attributable to changes in the benchmark interest rate during the periods from the effective dates of the swaps to the anticipated dates of forecasted debt issuances, which are expected to take place by 2024. These interest rate swaps are designated as cash flow hedges. The gains and losses related to these swaps are recorded to AOCI and will be recognized in "Interest expense, net" concurrently with the recognition of interest expense on the associated debt, once issued. If it becomes probable that a hedged forecasted transaction will no longer occur, the accumulated gains or losses on the derivative will be recognized currently in "Other, net" in the Condensed Statements of Consolidated Income (unaudited). There were no amounts excluded from effectiveness testing for derivatives in cash flow hedging relationships at March 31, 2021 and December 31, 2020.

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value	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 Condensed Consolidated Balance Sheets (unaudited) on a recurring basis and their level within the fair value hierarchy as of March 31, 2021 and December 31, 2020: Recurring Fair Value Measurements (in millions) Quoted Prices in Significant Significant Balance as of March 31, 2021 Assets Risk management assets $ — $ 4.2 $ — $ 4.2 Available-for-sale debt securities — 167.9 — 167.9 Total $ — $ 172.1 $ — $ 172.1 Liabilities Risk management liabilities $ — $ 101.0 $ — $ 101.0 Total $ — $ 101.0 $ — $ 101.0 Recurring Fair Value Measurements (in millions) Quoted Prices in Significant Significant Balance as of December 31, 2020 Assets Risk management assets $ — $ 13.2 $ — $ 13.2 Available-for-sale debt securities — 170.9 — 170.9 Total $ — $ 184.1 $ — $ 184.1 Liabilities Risk management liabilities $ — $ 222.8 $ — $ 222.8 Total $ — $ 222.8 $ — $ 222.8 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. 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. 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. 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 which reduce exposures. As of March 31, 2021 and December 31, 2020, 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. Credit risk is considered in the fair value calculation of each of our forward-starting interest rate swaps, as described in Note 9, "Risk Management Activities." As they are based on observable data and valuations of similar instruments, the hedges are categorized within Level 2 of the fair value hierarchy. There was no exchange of premium at the initial date of the swaps, and we can settle the contracts at any time. NIPSCO has entered into long-term forward natural gas purchase instruments to lock in a fixed price for its 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 9, “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. At each reporting date, we quantitatively and qualitatively assess available-for-sale debt securities for impairment. For securities in a loss position that we intend to hold, 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 the credit losses in the allowance for credit losses are deemed uncollectible, the allowance on the uncollectible portion is 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 are recognized immediately in earnings. As of March 31, 2021 and December 31, 2020, we recorded $0.3 million and $0.5 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 March 31, 2021 and December 31, 2020 were: March 31, 2021 (in millions) Amortized Gross Unrealized Gains Gross Unrealized Losses (1) Allowance for Credit Losses Fair Available-for-sale debt securities U.S. Treasury debt securities $ 37.1 $ 0.2 $ (0.3) $ — $ 37.0 Corporate/Other debt securities 126.7 5.3 (0.8) (0.3) 130.9 Total $ 163.8 $ 5.5 $ (1.1) $ (0.3) $ 167.9 December 31, 2020 (in millions) Amortized Gross Unrealized Gains Gross Unrealized Losses (2) Allowance for Credit Losses Fair Available-for-sale debt securities U.S. Treasury debt securities $ 33.7 $ 0.3 $ — $ — $ 34.0 Corporate/Other debt securities 130.2 7.7 (0.5) (0.5) 136.9 Total $ 163.9 $ 8.0 $ (0.5) $ (0.5) $ 170.9 (1) 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 $22.1 and $25.7 million, respectively, at March 31, 2021. (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 $0 million and $13.2 million, respectively, at December 31, 2020. Realized gains and losses on available-for-sale securities were immaterial for the three months ended March 31, 2021 and 2020. The cost of maturities sold is based upon specific identification. At March 31, 2021, approximately $6.2 million of U.S. Treasury debt securities and approximately $3.9 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 as of March 31, 2021 and December 31, 2020. Non-recurring Fair Value Measurements We measure the fair value of certain assets, including goodwill, on a non-recurring basis, typically annually or when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. In March 2021, we reached an agreement with Eversource regarding the final purchase price, including net working capital adjustments to the October 9, 2020 purchase price. The working capital amounts were measured at fair value, less costs to sell. B. Other Fair Value Disclosures for Financial Instruments. The carrying amount of cash and cash equivalents, restricted cash, 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. As of March 31, 2021, 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: (in millions) Carrying Amount as of March 31, 2021 Estimated Fair Value as of March 31, 2021 Carrying Estimated Fair Long-term debt (including current portion) $ 9,246.7 $ 10,178.0 $ 9,243.1 $ 11,034.2

Transfers Of Financial Assets

Transfers Of Financial Assets	3 Months Ended
	Mar. 31, 2021
Transfers and Servicing [Abstract]
Transfers Of Financial Assets	Transfers of Financial Assets 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 wholly owned and consolidated special purpose entities. The three agreements expire between August 2021 and May 2022 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 Condensed Consolidated Balance Sheets (unaudited). As of March 31, 2021, the maximum amount of debt that could be recognized related to our accounts receivable programs is $510.0 million. The following table reflects the gross receivables balance and net receivables transferred, as well as short-term borrowings related to the securitization transactions as of March 31, 2021 and December 31, 2020: (in millions) March 31, 2021 December 31, 2020 Gross receivables $ 630.8 $ 607.7 Less: Receivables not transferred 630.8 607.7 Net receivables transferred $ — $ — Short-term debt due to asset securitization $ — $ — For the three months ended March 31, 2021 and 2020, zero and $106.2 million, respectively, was recorded as cash flows from financing activities related to the change in short-term borrowings due to securitization transactions. Fees associated with the securitization transactions were $0.4 million and $0.7 million for the three months ended March 31, 2021 and 2020,

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The following presents our goodwill balance allocated by segment as of March 31, 2021: (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Goodwill $ 1,485.9 $ — $ — $ 1,485.9

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our interim effective tax rates reflect the estimated annual effective tax rates for 2021 and 2020, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended March 31, 2021 and 2020 were 17.4% and (24.5)%, respectively. These effective tax rates differ from the federal statutory tax rate of 21% primarily due to increased amortization of excess deferred federal income tax liabilities, as specified in the TCJA, tax credits, state income taxes and other permanent book-to-tax differences. These adjustments have a relative impact on the effective tax rate proportionally to pretax income or loss. The increase in the three month effective tax rate of 41.9% in 2021 compared to 2020 is primarily attributed to a discrete item related to the pre-tax book loss recorded for the classification as held for sale of the Massachusetts Business tax effected at statutory tax rates in 2020 offset by an increase in amortization of excess deferred federal income tax liabilities and deduction for AFUDC equity. There were no material changes recorded in 2021 to our uncertain tax positions recorded as of December 31, 2020.

Pension And Other Postretiremen

Pension And Other Postretirement Benefits	3 Months Ended
	Mar. 31, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension And Other Postretirement Benefits	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. We determined that, for certain rate-regulated subsidiaries, the future recovery of postretirement benefit costs is probable, and we record regulatory assets and liabilities for amounts that would otherwise have been recorded to expense or accumulated other comprehensive loss. Current rates of rate-regulated companies include postretirement benefit costs, including amortization of the regulatory assets and liabilities that arose prior to inclusion of these costs in rates. For most plans, cash contributions are remitted to grantor trusts. For the three months ended March 31, 2021, we contributed $0.7 million to our pension plans and $5.1 million to our other postretirement benefit plans. The following table provides the components of the plans’ actuarially determined net periodic benefit cost for the three months ended March 31, 2021 and 2020: Pension Benefits Other Postretirement Three Months Ended March 31, (in millions) 2021 2020 2021 2020 Components of Net Periodic Benefit (Income) Cost (1) Service cost $ 7.6 $ 8.0 $ 1.5 $ 1.6 Interest cost 7.7 13.5 2.5 3.9 Expected return on assets (25.8) (28.4) (3.8) (3.6) Amortization of prior service credit — 0.2 (0.6) (0.5) Recognized actuarial loss 5.3 8.7 1.2 1.3 Settlement loss 3.3 — — — Total Net Periodic Benefit (Income) Cost $ (1.9) $ 2.0 $ 0.8 $ 2.7 (1) The service cost component and all non-service cost components of net periodic benefit (income) cost are presented in "Operation and maintenance" and "Other, net", respectively, on the Condensed Statements of Consolidated Income (unaudited). During the first quarter of 2021, one of our qualified pension plans met the requirement for settlement accounting. A settlement charge of $3.3 million was recorded during the first quarter of 2021. As a result of the settlement, the pension plan was remeasured, resulting in a decrease to the net pension asset of $5.8 million, a net increase to regulatory assets of $2.1 million, and a net debit to accumulated other comprehensive loss of $0.4 million. Net periodic pension benefit cost for 2021 increased by $4.0 million as a result of the interim remeasurement. The following table provides the key assumptions that were used to calculate the pension benefit obligation and the net periodic benefit cost at the interim remeasurement date for the plan that triggered settlement accounting: February 28, 2021 Weighted-average Assumption to Determine Benefit Obligation Discount rate 2.57 % Weighted-average Assumptions to Determine Net Periodic Benefit Costs for the period ended Discount rate - service cost 2.81 % Discount rate - interest cost 1.57 % Expected return on assets 4.80 %

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2021
Variable Interest Entities [Abstract]
Variable Interest Entities	Variable Interest Entities A VIE is an entity in which the controlling interest is determined through means other than a majority voting interest. The primary beneficiary of a VIE is the business enterprise which has the power to direct the activities that most significantly impact the VIE’s economic performance. Also, the primary beneficiary either absorbs a significant amount of the VIE’s losses or has the right to receive benefits that could be significant to the VIE. We consider these qualitative elements in determining whether we are the primary beneficiary of a VIE, and we consolidate those VIEs for which we are determined to be the primary beneficiary. Rosewater (a joint venture) owns and operates 102 MW of nameplate capacity wind generation assets. Members of the joint venture are 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. Once the tax equity partner has earned their negotiated rate of return and we have reached the agreed upon contractual date, NIPSCO has the option to purchase at fair market value from the tax equity partner the remaining interest in the aforementioned joint venture. NIPSCO has an obligation to purchase, through a PPA at established market rates, 100% of the electricity generated by Rosewater. As the managing member of Rosewater, we control decisions that are significant to its ongoing operations and economic results. Therefore, we have concluded that we are the primary beneficiary of Rosewater and have consolidated Rosewater even though we own less than 100% of the total equity membership interest. We have determined that the use of HLBV accounting is reasonable and appropriate in order to attribute income and loss to the noncontrolling interest held by the tax equity partner. HLBV accounting was selected as the allocation of Rosewater's economic results to members differ from the members' relative ownership percentages. Using the HLBV method, our earnings are calculated based on how the partnership would distribute its cash if it were to hypothetically sell all of its assets for their carrying amounts and liquidate at each reporting period. Under HLBV, we calculate the liquidation value allocable to each partner at the beginning and end of each period based on the contractual terms of the related entity's operating agreement and adjust our income for the period to reflect the change in our associated book value. In March 2021, in exchange for additional respective membership interests in Rosewater, NIPSCO contributed $0.1 million in cash, and the tax equity partner contributed $7.5 million in cash, the second of two contractual cash contributions for each partner, per the equity capital contribution agreement. NIPSCO also assumed an additional obligation of $6.0 million to the developer, which comes due in 2023 and is included in "Other noncurrent liabilities" in the Condensed Consolidated Balance Sheets (unaudited). From the contributed funds, Rosewater paid $7.4 million to the developer of the wind generation assets. The developer of the facility is not a partner in the joint venture for federal income tax purposes and does not receive any share of earnings, tax attributes, or cash flows of Rosewater. With asset construction now complete, NIPSCO and the tax equity partner have made total cash contributions of $0.8 million and $93.6 million, respectively, and NIPSCO has assumed an obligation to the developer of $75.7 million, totaling contributions of $170.1 million for both partners. We did not provide any financial or other support during the year that was not previously contractually required, nor do we expect to provide such support in the future. At March 31, 2021 and December 31, 2020, $170.0 million and $156.4 million, respectively, in net assets (as detailed in the table below) related to Rosewater and the non-controlling interest attributable to the unrelated tax equity partner of $94.1 million and $85.6 million, respectively, were included in the Condensed Consolidated Balance Sheets (unaudited). For the quarters ended March 31, 2021 and 2020, $1.0 million and zero were allocated to the tax equity partner and is included in "Net income attributable to non-controlling interest" on the Condensed Statements of Consolidated Income. Our Condensed Consolidated Balance Sheets (unaudited) included the following assets and liabilities associated with Rosewater: (in millions) March 31, December 31, Net Property, Plant and Equipment $ 174.2 $ 175.6 Current assets 4.2 1.7 Total assets (1) $ 178.4 $ 177.3 Current liabilities $ 2.8 $ 15.3 Asset retirement obligations 5.5 5.5 Other noncurrent liabilities 0.1 0.1 Total liabilities $ 8.4 $ 20.9 (1) The assets of Rosewater represent assets of a consolidated VIE that can be used only to settle obligations of the consolidated VIE.

Short-Term Borrowings

Short-Term Borrowings	3 Months Ended
	Mar. 31, 2021
Short-term Debt [Abstract]
Short-Term Borrowings	Short-Term Borrowings We generate short-term borrowings from our revolving credit facility, commercial paper program and accounts receivable transfer programs. Each of these borrowing sources is described further below. 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 led by Barclays. We had no outstanding borrowings under this facility as of March 31, 2021 and December 31, 2020. Our commercial paper program has a program limit of up to $1.5 billion with a dealer group comprised of Barclays, Citigroup, Credit Suisse and Wells Fargo. We had $520.0 million of commercial paper outstanding as of March 31, 2021 and $503.0 million of commercial paper outstanding as of December 31, 2020. Refer to Note 11, "Transfers of Financial Assets," for additional information on our accounts receivable transfer programs. Short-term borrowings were as follows: (in millions) March 31, December 31, Commercial paper weighted-average interest rate of 0.19% and 0.27% at March 31, 2021 and December 31, 2020, respectively 520.0 503.0 Total Short-Term Borrowings $ 520.0 $ 503.0 Items listed above are presented net in the Condensed Statements of Consolidated Cash Flows (unaudited) as their maturities are less than 90 days.

Other Commitments And Contingen

Other Commitments And Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Other Commitments and Contingencies A. 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 a 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. As of March 31, 2021 and December 31, 2020, we had issued stand-by letters of credit of $15.2 million. We provide guarantees related to our future performance under BTAs for our renewable generation projects. At March 31, 2021, our guarantees for the Rosewater and Indiana Crossroads BTAs totaled $34.0 million. The amount of each guaranty will fluctuate upon the completion of the various steps outlined in each BTA. See “- D. Other Matters - Generation Transition,” below for more information. B. Legal Proceedings. On September 13, 2018, a series of fires and explosions occurred in Lawrence, Andover and North Andover, Massachusetts related to the delivery of natural gas by Columbia of Massachusetts (the "Greater Lawrence Incident"). The Greater Lawrence Incident resulted in one fatality and a number of injuries, damaged multiple homes and businesses, and caused the temporary evacuation of significant portions of each municipality. The Massachusetts Governor’s Office declared a state of emergency, authorizing the Massachusetts DPU to order another utility company to coordinate the restoration of utility services in Lawrence, Andover and North Andover. The incident resulted in the interruption of gas for approximately 7,500 gas meters, the majority of which served residences and approximately 700 of which served businesses, and the interruption of other utility service more broadly in the area. Columbia of Massachusetts replaced the cast iron and bare steel gas pipeline system in the affected area and restored service. See “- D. Other Matters - Greater Lawrence Pipeline Replacement” below for more information. On September 1, 2020, the Massachusetts Governor terminated the state of emergency declared following the Greater Lawrence Incident. We have been subject to inquiries and investigations by government authorities and regulatory agencies regarding the Greater Lawrence Incident, including the Massachusetts DPU and the Massachusetts Attorney General's Office. On February 26, 2020, the Company and Columbia of Massachusetts entered into agreements with the U.S. Attorney’s Office for the District of Massachusetts to resolve the U.S. Attorney’s Office’s investigation relating to the Greater Lawrence Incident, as described below. The Company and Columbia of Massachusetts entered into an agreement with the Massachusetts Attorney General’s Office (among other parties) to resolve the Massachusetts DPU and the Massachusetts Attorney General’s Office investigations, that was approved by the Massachusetts DPU on October 7, 2020 as part of the sale of the Massachusetts Business to Eversource. NTSB Investigation . As previously disclosed, the NTSB concluded its investigation into the Greater Lawrence Incident. On November 24, 2020, the NTSB closed NiSource’s one remaining open safety recommendation. U.S. Department of Justice Investigation. On February 26, 2020, the Company and Columbia of Massachusetts entered into agreements with the U.S. Attorney’s Office to resolve the U.S. Attorney’s Office’s investigation relating to the Greater Lawrence Incident. Columbia of Massachusetts agreed to plead guilty in the United States District Court for the District of Massachusetts (the “Court”) to violating the Natural Gas Pipeline Safety Act (the “Plea Agreement”), and the Company entered into a Deferred Prosecution Agreement (the “DPA”). On March 9, 2020, Columbia of Massachusetts entered its guilty plea pursuant to the Plea Agreement, which the Court accepted. Subsequently, Columbia of Massachusetts and the U.S. Attorney’s Office modified the Plea Agreement. On June 23, 2020, the Court sentenced Columbia of Massachusetts in accordance with the terms of the modified Plea Agreement. Under the modified Plea Agreement, Columbia of Massachusetts is subject to the following terms, among others: (i) a criminal fine in the amount of $53,030,116, which has been paid; (ii) a three year probationary period that will terminate early upon a sale of Columbia of Massachusetts or a sale of its gas distribution business to a qualified third-party buyer consistent with certain requirements, but in no event before the end of the one-year mandatory period of probation; (iii) compliance with each of the NTSB recommendations stemming from the Greater Lawrence Incident; and (iv) employment of an in-house monitor until the end of the term of probation or until the sale of Columbia of Massachusetts or its gas distribution business, whichever is earlier. On October 13, 2020, the Court, upon agreement of the U.S. Attorney's Office and Columbia Gas of Massachusetts, modified the terms of probation by ending the term of the in-house monitor. Under the DPA, the U.S. Attorney’s Office agreed to defer prosecution of the Company in connection with the Greater Lawrence Incident for a three-year period (which three-year period may be extended for twelve (12) months upon the U.S. Attorney’s Office’s determination of a breach of the DPA) subject to certain obligations of the Company, including, but not limited to, the following: (i) the Company will use reasonable best efforts to sell Columbia of Massachusetts or Columbia of Massachusetts’ gas distribution business to a qualified third-party buyer consistent with certain requirements, and, upon the completion of any such sale, the Company will cease and desist any and all gas pipeline and distribution activities in the District of Massachusetts; (ii) the Company will forfeit and pay, within 30 days of the later of the sale becoming final or the date on which post-closing adjustments to the purchase price are finally determined in accordance with the agreement to sell Columbia of Massachusetts or its gas distribution business, a fine equal to the total amount of the profit or gain, if any, from any sale of Columbia of Massachusetts or its gas distribution business, with the amount of profit or gain determined as provided in the DPA; and (iii) the Company agrees as to each of the Company’s subsidiaries involved in the distribution of gas through pipeline facilities in Massachusetts, Indiana, Ohio, Pennsylvania, Maryland, Kentucky and Virginia to implement and adhere to each of the recommendations from the NTSB stemming from the Greater Lawrence Incident. Pursuant to the DPA, if the Company complies with all of its obligations under the DPA, including, but not limited to those identified above, the U.S. Attorney’s Office will not file any criminal charges against the Company related to the Greater Lawrence Incident. If Columbia of Massachusetts withdraws its plea for any reason, if the Court rejects any aspect of the Plea Agreement, or if Columbia of Massachusetts should fail to perform an obligation under the Plea Agreement prior to the sale of Columbia of Massachusetts or its gas distribution business, the U.S. Attorney's Office may, at its sole option, render the DPA null and void. The sale of the Massachusetts Business was completed on October 9, 2020. The Company was not required to forfeit or pay any funds because the Company did not realize a profit or gain from the sale as provided in the DPA. Private Actions. Various lawsuits, including several purported class action lawsuits, have been filed by various affected residents or businesses in Massachusetts state courts against the Company and/or Columbia of Massachusetts in connection with the Greater Lawrence Incident. On July 26, 2019, the Company, Columbia of Massachusetts and NiSource Corporate Services Company, a subsidiary of the Company, entered into a term sheet with the class action plaintiffs under which they agreed to settle the class action claims in connection with the Greater Lawrence Incident. Columbia of Massachusetts agreed to pay $143 million into a settlement fund to compensate the settlement class and the settlement class agreed to release Columbia of Massachusetts and affiliates from all claims arising out of or related to the Greater Lawrence Incident. The following claims are not covered under the proposed settlement because they are not part of the consolidated class action: (1) physical bodily injury and wrongful death; (2) insurance subrogation, whether equitable, contractual or otherwise; and (3) claims arising out of appliances that are subject to the Massachusetts DPU orders. Emotional distress and similar claims are covered under the proposed settlement unless they are secondary to a physical bodily injury. The settlement class is defined under the term sheet as all persons and businesses in the three municipalities of Lawrence, Andover and North Andover, Massachusetts, subject to certain limited exceptions. The motion for preliminary approval and the settlement documents were filed on September 25, 2019. The preliminary approval court hearing was held on October 7, 2019 and the court issued an order granting preliminary approval of the settlement on October 11, 2019. The Court granted final approval of the settlement on March 12, 2020. With respect to claims not included in the consolidated class action, many of the asserted wrongful death and bodily injury claims have settled, and we continue to discuss potential settlements with remaining claimants. The outcomes and impacts of such private actions are uncertain at this time. Shareholder Derivative Lawsuit. On April 28, 2020, a shareholder derivative lawsuit was filed by the City of Detroit Police and Fire Retirement System in the United States District Court for the District of Delaware against certain of the Company’s current and former directors, alleging state-law claims for breaches of fiduciary duty with respect to the pipeline safety management systems relating to the distribution of natural gas prior to the Greater Lawrence Incident and also including federal-law claims related to our proxy statement disclosures regarding our safety systems. The remedies sought included damages for the alleged breaches of fiduciary duty, corporate governance reforms, and restitution of any unjust enrichment. The defendants filed a motion to dismiss the lawsuit, and oral argument was held on March 2, 2021. On March 9, 2021, the district court granted the defendants’ motion to dismiss. It dismissed the federal-law claims with prejudice for failure to state a claim on which relief can be granted and declined to exercise jurisdiction over the state-law claims, which were dismissed without prejudice. Following the dismissal of the federal court action, on April 29, 2021, the same plaintiff filed a shareholder derivative lawsuit in the Delaware Court of Chancery against certain of our current and former directors. The new complaint alleges a single count for breach of fiduciary duty, and no longer alleges disclosure violations or breaches of federal securities laws. The complaint relates to substantially the same matters as those alleged in the dismissed federal derivative complaint. The remedies sought include damages for the alleged breaches of fiduciary duty, corporate governance reforms, and restitution of compensation by the individual defendants. The case is at an early stage, and a schedule has not yet been entered. Because of the preliminary nature of this lawsuit, we are not able to estimate a loss or range of loss, if any, that may be incurred in connection with this matter at this time. Financial Impact. Since the Greater Lawrence Incident, we have recorded expenses of approximately $1,040 million for third-party claims and fines, penalties and settlements associated with government investigations. These costs do not include the capital cost of the pipeline replacement. Refer to " - D. Other Matters - Greater Lawrence Incident Restoration," and "- Greater Lawrence Incident Pipeline Replacement," for additional information. The process for estimating costs associated with third-party claims relating to the Greater Lawrence Incident requires management to exercise significant judgment based on a number of assumptions and subjective factors. As more information becomes known, management’s estimates and assumptions regarding the financial impact of the Greater Lawrence Incident may change. 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, none of which we believe to be individually material at this time. Due to the inherent uncertainty of litigation, there can be no assurance that the outcome or resolution of any particular claim, proceeding or investigation related to the Greater Lawrence Incident or otherwise would not have a material adverse effect on our results of operations, financial position or liquidity. Certain matters in connection with the Greater Lawrence Incident have had or may have a material impact as described above. If one or more of such additional or 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. C. 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 a majority of environmental assessment and remediation costs to be recoverable through rates for certain of our companies. As of March 31, 2021 and December 31, 2020, we had recorded a liability of $90.6 million and $92.6 million, respectively, to cover environmental remediation at various sites. The current portion of this liability is included in "Other accruals" in the Condensed Consolidated Balance Sheets (unaudited). The noncurrent portion is included in "Other noncurrent liabilities." 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 (commonly known as Superfund) 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. These liabilities are not material to the Condensed Consolidated Financial Statements (unaudited). MGP. We maintain a program to identify and investigate former MGP sites where Gas Distribution Operations subsidiaries or predecessors may have liability. The program has identified 54 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. No material changes to the estimated future remediation costs were noted as a result of the refresh completed as of June 30, 2020. Our total estimated liability related to the facilities subject to remediation was $84.3 million and $85.0 million at March 31, 2021 and December 31, 2020, respectively. The liability represents our best estimate of the probable cost to remediate the MGP sites. We believe that it is reasonably possible that remediation costs could vary by as much as $20 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. On April 17, 2015, the EPA issued a final rule for regulation of CCRs. The rule regulates CCRs under the RCRA Subtitle D, which determines them to be nonhazardous. The rule is implemented in phases and requires increased groundwater monitoring, reporting, recordkeeping and posting of related information to the Internet. The rule also establishes requirements related to CCR management and disposal. The rule allows NIPSCO to continue its byproduct beneficial use program. To comply with the rule, NIPSCO completed capital expenditures in 2019 to modify its infrastructure and manage CCRs. The CCR rule also resulted in 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. NIPSCO will also continue to work with EPA and the Indiana Department of Environmental Management to obtain administrative approvals associated with the CCR rule. In the event that the approvals are not obtained, future operations could be impacted. We believe the possibility of such an outcome is remote. D. Other Matters. Generation Transition. NIPSCO has executed several PPAs to purchase 100% of the output from renewable generation facilities at a fixed price per MWh. Each facility supplying the energy will have an associated nameplate capacity, and payments under the PPAs will not begin until the associated generation facility is constructed by the owner/seller. NIPSCO has also executed several BTAs with developers to construct renewable generation facilities. NIPSCO's purchase requirement under the BTAs is dependent on satisfactory approval of the BTA by the IURC, successful execution of an agreement with a tax equity partner and timely completion of construction. NIPSCO and the tax equity partner are obligated to make cash contributions to the partnership at the date construction is substantially complete. Once the tax equity partner has earned their negotiated rate of return and we have reached the agreed upon contractual date, NIPSCO has the option to purchase at fair market value from the tax equity partner the remaining interest in the aforementioned joint venture. Greater Lawrence Incident Restoration . In addition to the amounts estimated for third-party claims and fines, penalties and settlements associated with government investigations described above, we have recorded expenses for other incident-related costs. Such costs include certain consulting costs, legal costs, vendor costs, claims center costs, labor and related expenses incurred in connection with the incident, and insurance-related loss surcharges. These costs were immaterial for the three months ended March 31, 2021. Greater Lawrence Pipeline Replacement . In connection with the Greater Lawrence Incident, Columbia of Massachusetts, in cooperation with the Massachusetts Governor’s office, replaced the entire affected pipeline system. We invested approximately $258 million of capital spend for the pipeline replacement; this work was completed in 2019. We maintain property insurance for gas pipelines and other applicable property. Columbia of Massachusetts has filed a proof of loss with its property insurer for the pipeline replacement. In January 2020, we filed a lawsuit against the property insurer, seeking payment of our property claim. We are currently unable to predict the timing or amount of any insurance recovery under the property policy. State Income Taxes Related to Greater Lawrence Incident Expenses . As of December 31, 2018, expenses related to the Greater Lawrence Incident were $1,023 million. In the fourth quarter of 2019, we filed an application for Alternative Apportionment with the MA DOR to request an allocable approach to these expenses for purposes of Massachusetts state income taxes, which, if approved, would result in a state deferred tax asset of approximately $50 million, net. The MA DOR issued a denial during the first quarter of 2020. We filed an application for abatement in the second quarter of 2020, which resulted in a denial from the MA DOR in April 2021. We have 60 days to submit an appeal for this decision. One-Time Employee Separation Benefits. On August 5, 2020, we commenced a voluntary separation program for certain employees. Expense for the voluntary separation program was predominantly recognized in the third quarter of 2020, when the employees accepted the offer, absent a retention period. In addition, we have continued to evaluate our organizational structure under the auspices of NiSource Next, which has resulted in additional separations under our existing severance policies. For employees that have a retention period, expense will be recognized over the remaining service period. The total estimated severance expense for employees is approximately $40 million, with $38.1 million incurred to date. A rollforward of the one-time employee separation benefits accrual for the three months ended March 31, 2021 is presented below: (in millions) Balance as of January 1, 2021 Changes Attributable to Costs Incurred (1) Costs Paid Adjustments Balance as of March 31, 2021 (2) One-time Employee Separation Benefits 11.1 4.6 (8.4) — 7.3 (1) This activity is presented within "Operation and maintenance" in our Condensed Statements of Consolidated Income (unaudited).

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2021
Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following tables display the components of Accumulated Other Comprehensive Loss: (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of January 1, 2021 $ 6.0 $ (147.9) $ (14.8) $ (156.7) Other comprehensive income (loss) before reclassifications (2.2) 84.6 (1.4) 81.0 Amounts reclassified from accumulated other comprehensive income (loss) (0.3) — 0.5 0.2 Net current-period other comprehensive income (loss) (2.5) 84.6 (0.9) 81.2 Balance as of March 31, 2021 $ 3.5 $ (63.3) $ (15.7) $ (75.5) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of January 1, 2020 $ 3.3 $ (77.2) $ (18.7) $ (92.6) Other comprehensive income (loss) before reclassifications (5.2) (133.3) 0.4 (138.1) Amounts reclassified from accumulated other comprehensive income (loss) (0.2) — 0.3 0.1 Net current-period other comprehensive income (loss) (5.4) (133.3) 0.7 (138.0) Balance as of March 31, 2020 $ (2.1) $ (210.5) $ (18.0) $ (230.6) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Other, Net

Other, Net	3 Months Ended
	Mar. 31, 2021
Other, Net [Abstract]
Other, Net	Other, Net Three Months Ended March 31, (in millions) 2021 2020 Interest income $ 0.9 $ 1.7 AFUDC equity 1.5 1.7 Pension and other postretirement non-service benefit 8.5 2.7 Miscellaneous (0.4) (0.7) Total Other, net $ 10.5 $ 5.4

Business Segment Information

Business Segment Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Business Segment Information	Business Segment Information At March 31, 2021, our operations are divided into two primary reportable segments, the Gas Distribution Operations and Electric Operations segments. Corporate costs and other activities that are not significant on a stand-alone basis to warrant treatment as an operating segment and that do not fit into one of our two segments are aggregated as "Corporate and Other" in the disclosures below. Refer to Note 3, "Revenue Recognition," for additional information on our segments and their sources of revenues. The following table provides information about our business segments. We use operating income as our primary measurement for each of the reported segments and make decisions on finance, dividends and taxes at the corporate level on a consolidated basis. 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. Three Months Ended (in millions) 2021 2020 Operating Revenues Gas Distribution Operations Unaffiliated $ 1,135.8 $ 1,228.0 Intersegment 3.1 3.0 Total 1,138.9 1,231.0 Electric Operations Unaffiliated 402.5 377.3 Intersegment 0.2 0.2 Total 402.7 377.5 Corporate and Other Unaffiliated 7.3 0.2 Intersegment 103.9 106.7 Total 111.2 106.9 Eliminations (107.2) (109.9) Consolidated Operating Revenues $ 1,545.6 $ 1,605.5 Operating Income (Loss) Gas Distribution Operations $ 346.9 $ 78.5 Electric Operations 87.9 78.5 Corporate and Other (1.6) (8.8) Consolidated Operating Income $ 433.2 $ 148.2

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event On April 19, 2021, we completed the sale of 8.625 million Series A Equity Units (“Equity Units”), initially consisting of Series A Corporate Units (“Corporate Units”), each with a stated amount of $100. The offering generated net proceeds of $835.5 million , after underwriting and estimated issuance expenses. Each Corporate Unit consists of a forward contract to purchase shares of our common stock in the future and a 1/10th, or 10%, undivided beneficial ownership interest in one share of Series C Mandatory Convertible Preferred Stock, par value $0.01 per share, with a liquidation preference of $1,000 per share. The Mandatory Convertible Preferred Stock initially will not bear any dividends. Total annual distributions of the Corporate Units will be 7.75%, consisting of quarterly contract adjustment payments under the forward contract. We may pay the contract adjustment payments in cash, shares of common stock or a combination of cash and shares of common stock, at our election.

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Tables)	3 Months Ended
	Mar. 31, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
Description of New Accounting Pronouncements Not yet Adopted	Recently Issued Accounting Pronouncements We are currently evaluating the impact of certain ASUs on our Condensed Consolidated Financial Statements (unaudited) and Notes to Condensed Consolidated Financial Statements (unaudited), which are described below: Standard Description Effective Date Effect on the financial statements or other significant matters ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Statement This pronouncement provides Upon issuance on We continue to evaluate the temporary expedients and options available under this guidance, and the effects of this pronouncement on our Condensed Consolidated Financial Statements (unaudited) and Notes to Condensed Consolidated Financial Statements (unaudited). We are currently identifying and evaluating contracts that may be impacted. As of March 31, 2021, we have not applied any expedients and options available under this ASU. ASU 2021-01, Reference Rate Reform (Topic 848): Scope ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivative and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity This pronouncement simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity's own equity. Specifically, the ASU "simplifies accounting for convertible instruments by removing major separation models required under current GAAP." In addition, the ASU "removes certain settlement conditions that are required for equity contracts to qualify for it" and "simplifies the diluted earnings per share (EPS) calculations in certain areas." Annual period beginning after December 15, 2021, and interim periods within those fiscal years. We continue to evaluate the effects of this pronouncement on our Condensed Consolidated Financial Statements (unaudited) and Notes to Condensed Consolidated Financial Statements (unaudited) as it pertains to any relevant future activity. We expect to adopt this ASU on its effective date.
Schedule of Prospective Adoption of New Accounting Pronouncements	Recently Adopted Accounting Pronouncements Standard Adoption ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes This pronouncement simplifies the accounting for income taxes by eliminating certain exceptions to the general principles in ASC 740, income taxes. It also improves consistency of application for other areas of the guidance by clarifying and amending existing guidance. We adopted the amendments of this pronouncement as of January 1, 2021 with no material impact to the Condensed Consolidated Financial Statements (unaudited).

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2021
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 Condensed Statements of Consolidated Income (unaudited) for the three months ended March 31, 2021 and March 31, 2020: Three Months Ended March 31, 2021 (in millions) Gas Distribution Operations Electric Operations Corporate and Other (2) Total Customer Revenues (1) Residential $ 773.5 $ 129.2 $ — $ 902.7 Commercial 271.4 122.9 — 394.3 Industrial 57.9 122.9 — 180.8 Off-system 14.4 — — 14.4 Miscellaneous 9.9 4.2 0.2 14.3 Total Customer Revenues $ 1,127.1 $ 379.2 $ 0.2 $ 1,506.5 Other Revenues 8.7 23.3 7.1 39.1 Total Operating Revenues $ 1,135.8 $ 402.5 $ 7.3 $ 1,545.6 (1) Customer revenue amounts exclude intersegment revenues. See Note 20, "Business Segment Information," for discussion of intersegment revenues. (2) Other revenues related to the Transition Services Agreement entered into in connection with the sale of the Massachusetts Business. Three Months Ended March 31, 2020 (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Customer Revenues (1) Residential $ 796.5 $ 119.2 $ — $ 915.7 Commercial 269.4 120.2 — 389.6 Industrial 74.2 109.1 — 183.3 Off-system 18.7 — — 18.7 Miscellaneous 12.5 5.9 0.2 18.6 Total Customer Revenues $ 1,171.3 $ 354.4 $ 0.2 $ 1,525.9 Other Revenues 56.7 22.9 — 79.6 Total Operating Revenues $ 1,228.0 $ 377.3 $ 0.2 $ 1,605.5
Customer Accounts Receivable	The opening and closing balances of customer receivables for the three months ended March 31, 2021 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, 2020 $ 400.0 $ 327.2 Balance as of March 31, 2021 507.4 244.3 Increase (Decrease) $ 107.4 $ (82.9)
Financing Receivable, Allowance for Credit Loss	A rollforward of our allowance for credit losses for the three months ended March 31, 2021 are presented in the table below: Three Months Ended March 31, 2021 ( in millions ) Gas Distribution Operations Electric Operations Corporate and Other Total Beginning balance $ 41.8 $ 9.7 $ 0.8 $ 52.3 Current period provisions 5.9 2.9 — 8.8 Write-offs charged against allowance (9.0) (2.4) — (11.4) Recoveries of amounts previously written off 4.1 0.1 — 4.2 Ending balance of the allowance for credit losses $ 42.8 $ 10.3 $ 0.8 $ 53.9

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Computation Of Diluted Average Common Shares	The computation of diluted average common shares is as follows: Three Months Ended March 31, (in thousands) 2021 2020 Basic average common shares outstanding 392,657 383,062 Dilutive potential common shares: Shares contingently issuable under employee stock plans 630 845 Shares restricted under employee stock plans 288 207 Forward Agreement 337 — Diluted Average Common Shares 393,912 384,114

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Stock by Class - Preferred	The following table displays preferred dividends declared for the period by outstanding series of shares: Three Months Ended March December 31, 2021 2020 2021 2020 (in millions except shares and per share amounts) Liquidation Preference Per Share Shares Dividends Declared Per Share Outstanding 5.650% Series A $ 1,000.00 400,000 28.25 28.25 $ 393.9 $ 393.9 6.500% Series B $ 25,000.00 20,000 812.50 812.50 $ 486.1 $ 486.1

Regulatory Matters (Tables)

Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2021
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of COVID-19 Regulatory Impact	The ongoing impacts of these approvals or directives are described in the table below: Jurisdiction Moratorium in Place? Regulatory Asset balance as of March 31, 2021 (in millions) Deferred COVID-19 Costs Columbia of Ohio No $ 2.0 Incremental operation and maintenance expenses NIPSCO No $ 12.0 Incremental bad debt expense and the costs to implement the requirements of the COVID-19 related order Columbia of Pennsylvania No $ 7.1 Incremental bad debt expense incurred since March 13, 2020 above levels currently in rates Columbia of Virginia Yes $ 0.1 Incremental incurred costs, subject to an earnings test review Columbia of Maryland No $ 1.1 Incremental costs (including incremental bad debt expense) incurred to ensure that customers have essential utility service during the state of emergency in Maryland. Such incremental costs must be offset by any benefit received in connection with the pandemic

Risk Management Activities (Tab

Risk Management Activities (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Risk management assets and liabilities on our derivatives are presented on the Condensed Consolidated Balance Sheets (unaudited) as shown below: (in millions) March 31, 2021 December 31, 2020 Risk Management Assets - Current (1) Interest rate risk programs $ — $ — Commodity price risk programs 1.0 10.4 Total $ 1.0 $ 10.4 Risk Management Assets - Noncurrent (2) Interest rate risk programs $ — $ — Commodity price risk programs 3.2 2.8 Total $ 3.2 $ 2.8 Risk Management Liabilities - Current (3) Interest rate risk programs $ 17.1 $ 70.9 Commodity price risk programs 5.0 7.3 Total $ 22.1 $ 78.2 Risk Management Liabilities - Noncurrent (4) Interest rate risk programs $ 40.6 $ 99.5 Commodity price risk programs 38.3 45.1 Total $ 78.9 $ 144.6 (1) Presented in "Prepayments and other" on the Condensed Consolidated Balance Sheets (unaudited). (2) Presented in "Deferred charges and other" on the Condensed Consolidated Balance Sheets (unaudited). (3) Presented in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited).

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2021
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 Condensed Consolidated Balance Sheets (unaudited) on a recurring basis and their level within the fair value hierarchy as of March 31, 2021 and December 31, 2020: Recurring Fair Value Measurements (in millions) Quoted Prices in Significant Significant Balance as of March 31, 2021 Assets Risk management assets $ — $ 4.2 $ — $ 4.2 Available-for-sale debt securities — 167.9 — 167.9 Total $ — $ 172.1 $ — $ 172.1 Liabilities Risk management liabilities $ — $ 101.0 $ — $ 101.0 Total $ — $ 101.0 $ — $ 101.0 Recurring Fair Value Measurements (in millions) Quoted Prices in Significant Significant Balance as of December 31, 2020 Assets Risk management assets $ — $ 13.2 $ — $ 13.2 Available-for-sale debt securities — 170.9 — 170.9 Total $ — $ 184.1 $ — $ 184.1 Liabilities Risk management liabilities $ — $ 222.8 $ — $ 222.8 Total $ — $ 222.8 $ — $ 222.8
Schedule of Available-For-Sale Securities	The amortized cost, gross unrealized gains and losses, allowance for credit losses, and fair value of available-for-sale securities at March 31, 2021 and December 31, 2020 were: March 31, 2021 (in millions) Amortized Gross Unrealized Gains Gross Unrealized Losses (1) Allowance for Credit Losses Fair Available-for-sale debt securities U.S. Treasury debt securities $ 37.1 $ 0.2 $ (0.3) $ — $ 37.0 Corporate/Other debt securities 126.7 5.3 (0.8) (0.3) 130.9 Total $ 163.8 $ 5.5 $ (1.1) $ (0.3) $ 167.9 December 31, 2020 (in millions) Amortized Gross Unrealized Gains Gross Unrealized Losses (2) Allowance for Credit Losses Fair Available-for-sale debt securities U.S. Treasury debt securities $ 33.7 $ 0.3 $ — $ — $ 34.0 Corporate/Other debt securities 130.2 7.7 (0.5) (0.5) 136.9 Total $ 163.9 $ 8.0 $ (0.5) $ (0.5) $ 170.9 (1) 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 $22.1 and $25.7 million, respectively, at March 31, 2021. (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 $0 million and $13.2 million, respectively, at December 31, 2020.
Carrying Amount And Estimated Fair Values Of Financial Instruments	The carrying amount and estimated fair values of these financial instruments were as follows: (in millions) Carrying Amount as of March 31, 2021 Estimated Fair Value as of March 31, 2021 Carrying Estimated Fair Long-term debt (including current portion) $ 9,246.7 $ 10,178.0 $ 9,243.1 $ 11,034.2

Transfers Of Financial Assets (

Transfers Of Financial Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Transfers and Servicing [Abstract]
Schedule Of Gross And Net Receivables Transferred As Well As Short-Term Borrowings Related To The Securitization Transactions	The following table reflects the gross receivables balance and net receivables transferred, as well as short-term borrowings related to the securitization transactions as of March 31, 2021 and December 31, 2020: (in millions) March 31, 2021 December 31, 2020 Gross receivables $ 630.8 $ 607.7 Less: Receivables not transferred 630.8 607.7 Net receivables transferred $ — $ — Short-term debt due to asset securitization $ — $ —

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following presents our goodwill balance allocated by segment as of March 31, 2021: (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Goodwill $ 1,485.9 $ — $ — $ 1,485.9

Pension And Other Postretirem_2

Pension And Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Components Of The Plans' Net Periodic Benefits Cost	The following table provides the components of the plans’ actuarially determined net periodic benefit cost for the three months ended March 31, 2021 and 2020: Pension Benefits Other Postretirement Three Months Ended March 31, (in millions) 2021 2020 2021 2020 Components of Net Periodic Benefit (Income) Cost (1) Service cost $ 7.6 $ 8.0 $ 1.5 $ 1.6 Interest cost 7.7 13.5 2.5 3.9 Expected return on assets (25.8) (28.4) (3.8) (3.6) Amortization of prior service credit — 0.2 (0.6) (0.5) Recognized actuarial loss 5.3 8.7 1.2 1.3 Settlement loss 3.3 — — — Total Net Periodic Benefit (Income) Cost $ (1.9) $ 2.0 $ 0.8 $ 2.7 (1) The service cost component and all non-service cost components of net periodic benefit (income) cost are presented in "Operation and maintenance" and "Other, net", respectively, on the Condensed Statements of Consolidated Income (unaudited).
Schedule of Defined Benefit Plans Disclosures	The following table provides the key assumptions that were used to calculate the pension benefit obligation and the net periodic benefit cost at the interim remeasurement date for the plan that triggered settlement accounting: February 28, 2021 Weighted-average Assumption to Determine Benefit Obligation Discount rate 2.57 % Weighted-average Assumptions to Determine Net Periodic Benefit Costs for the period ended Discount rate - service cost 2.81 % Discount rate - interest cost 1.57 % Expected return on assets 4.80 %

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2021
Variable Interest Entities [Abstract]
Variable Interest Entities Assets and Liabilities	Our Condensed Consolidated Balance Sheets (unaudited) included the following assets and liabilities associated with Rosewater: (in millions) March 31, December 31, Net Property, Plant and Equipment $ 174.2 $ 175.6 Current assets 4.2 1.7 Total assets (1) $ 178.4 $ 177.3 Current liabilities $ 2.8 $ 15.3 Asset retirement obligations 5.5 5.5 Other noncurrent liabilities 0.1 0.1 Total liabilities $ 8.4 $ 20.9 (1) The assets of Rosewater represent assets of a consolidated VIE that can be used only to settle obligations of the consolidated VIE.

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	3 Months Ended
	Mar. 31, 2021
Short-term Debt [Abstract]
Schedule Of Short-Term Borrowings	Short-term borrowings were as follows: (in millions) March 31, December 31, Commercial paper weighted-average interest rate of 0.19% and 0.27% at March 31, 2021 and December 31, 2020, respectively 520.0 503.0 Total Short-Term Borrowings $ 520.0 $ 503.0

Other Commitments And Conting_2

Other Commitments And Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Restructuring Reserve by Type of Cost	A rollforward of the one-time employee separation benefits accrual for the three months ended March 31, 2021 is presented below: (in millions) Balance as of January 1, 2021 Changes Attributable to Costs Incurred (1) Costs Paid Adjustments Balance as of March 31, 2021 (2) One-time Employee Separation Benefits 11.1 4.6 (8.4) — 7.3 (1) This activity is presented within "Operation and maintenance" in our Condensed Statements of Consolidated Income (unaudited).

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2021
Other Comprehensive Income (Loss), Tax [Abstract]
Components Of Accumulated Other Comprehensive Loss	The following tables display the components of Accumulated Other Comprehensive Loss: (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of January 1, 2021 $ 6.0 $ (147.9) $ (14.8) $ (156.7) Other comprehensive income (loss) before reclassifications (2.2) 84.6 (1.4) 81.0 Amounts reclassified from accumulated other comprehensive income (loss) (0.3) — 0.5 0.2 Net current-period other comprehensive income (loss) (2.5) 84.6 (0.9) 81.2 Balance as of March 31, 2021 $ 3.5 $ (63.3) $ (15.7) $ (75.5) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of January 1, 2020 $ 3.3 $ (77.2) $ (18.7) $ (92.6) Other comprehensive income (loss) before reclassifications (5.2) (133.3) 0.4 (138.1) Amounts reclassified from accumulated other comprehensive income (loss) (0.2) — 0.3 0.1 Net current-period other comprehensive income (loss) (5.4) (133.3) 0.7 (138.0) Balance as of March 31, 2020 $ (2.1) $ (210.5) $ (18.0) $ (230.6) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Other, Net (Tables)

Other, Net (Tables)	3 Months Ended
	Mar. 31, 2021
Other, Net [Abstract]
Schedule of Other Nonoperating Income (Expense)	Three Months Ended March 31, (in millions) 2021 2020 Interest income $ 0.9 $ 1.7 AFUDC equity 1.5 1.7 Pension and other postretirement non-service benefit 8.5 2.7 Miscellaneous (0.4) (0.7) Total Other, net $ 10.5 $ 5.4

Business Segment Information (T

Business Segment Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule Of Operating Income Derived From Revenues And Expenses By Segment	At March 31, 2021, our operations are divided into two primary reportable segments, the Gas Distribution Operations and Electric Operations segments. Corporate costs and other activities that are not significant on a stand-alone basis to warrant treatment as an operating segment and that do not fit into one of our two segments are aggregated as "Corporate and Other" in the disclosures below. Refer to Note 3, "Revenue Recognition," for additional information on our segments and their sources of revenues. The following table provides information about our business segments. We use operating income as our primary measurement for each of the reported segments and make decisions on finance, dividends and taxes at the corporate level on a consolidated basis. 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. Three Months Ended (in millions) 2021 2020 Operating Revenues Gas Distribution Operations Unaffiliated $ 1,135.8 $ 1,228.0 Intersegment 3.1 3.0 Total 1,138.9 1,231.0 Electric Operations Unaffiliated 402.5 377.3 Intersegment 0.2 0.2 Total 402.7 377.5 Corporate and Other Unaffiliated 7.3 0.2 Intersegment 103.9 106.7 Total 111.2 106.9 Eliminations (107.2) (109.9) Consolidated Operating Revenues $ 1,545.6 $ 1,605.5 Operating Income (Loss) Gas Distribution Operations $ 346.9 $ 78.5 Electric Operations 87.9 78.5 Corporate and Other (1.6) (8.8) Consolidated Operating Income $ 433.2 $ 148.2

Revenue Recognition (Narrative)

Revenue Recognition (Narrative) (Details)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Service Area By County	20

Revenue Recognition (Disaggrega

Revenue Recognition (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Customer revenues	$ 1,506.5	$ 1,525.9
Other revenues	39.1	79.6
Total Operating Revenues	1,545.6	1,605.5
Gas Distribution Operations
Disaggregation of Revenue [Line Items]
Customer revenues	1,127.1	1,171.3
Other revenues	8.7	56.7
Total Operating Revenues	1,135.8	1,228
Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues	379.2	354.4
Other revenues	23.3	22.9
Total Operating Revenues	402.5	377.3
Corporate and Other
Disaggregation of Revenue [Line Items]
Customer revenues	0.2	0.2
Other revenues	7.1	0
Total Operating Revenues	7.3	0.2
Residential
Disaggregation of Revenue [Line Items]
Customer revenues	902.7	915.7
Residential | Gas Distribution Operations
Disaggregation of Revenue [Line Items]
Customer revenues	773.5	796.5
Residential | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues	129.2	119.2
Residential | Corporate and Other
Disaggregation of Revenue [Line Items]
Customer revenues	0	0
Commercial
Disaggregation of Revenue [Line Items]
Customer revenues	394.3	389.6
Commercial | Gas Distribution Operations
Disaggregation of Revenue [Line Items]
Customer revenues	271.4	269.4
Commercial | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues	122.9	120.2
Commercial | Corporate and Other
Disaggregation of Revenue [Line Items]
Customer revenues	0	0
Industrial
Disaggregation of Revenue [Line Items]
Customer revenues	180.8	183.3
Industrial | Gas Distribution Operations
Disaggregation of Revenue [Line Items]
Customer revenues	57.9	74.2
Industrial | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues	122.9	109.1
Industrial | Corporate and Other
Disaggregation of Revenue [Line Items]
Customer revenues	0	0
Off-system
Disaggregation of Revenue [Line Items]
Customer revenues	14.4	18.7
Off-system | Gas Distribution Operations
Disaggregation of Revenue [Line Items]
Customer revenues	14.4	18.7
Off-system | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues	0	0
Off-system | Corporate and Other
Disaggregation of Revenue [Line Items]
Customer revenues	0	0
Miscellaneous
Disaggregation of Revenue [Line Items]
Customer revenues	14.3	18.6
Miscellaneous | Gas Distribution Operations
Disaggregation of Revenue [Line Items]
Customer revenues	9.9	12.5
Miscellaneous | Electric Operations
Disaggregation of Revenue [Line Items]
Customer revenues	4.2	5.9
Miscellaneous | Corporate and Other
Disaggregation of Revenue [Line Items]
Customer revenues	$ 0.2	$ 0.2

Revenue Recognition (Customer A

Revenue Recognition (Customer Accounts Receivable) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Customer Accounts Receivable, Billed (Less Reserve)	$ 507.4	$ 400
Customer Accounts Receivable, Unbilled (Less Reserve)	244.3	$ 327.2
Increase (Decrease) in Customer Accounts Receivable, Billed (Less Reserve)	107.4
Increase (Decrease) in Customer Accounts Receivable, Unbilled (Less Reserve)	$ (82.9)

Revenue Recognition Revenue Rec

Revenue Recognition Revenue Recognition (Allowance for Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	$ 53.9	$ 52.3
Current period provisions	8.8
Write-offs charged against allowance	(11.4)
Recoveries of amounts previously written off	4.2
Gas Distribution Operations
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	42.8	41.8
Current period provisions	5.9
Write-offs charged against allowance	(9)
Recoveries of amounts previously written off	4.1
Electric Operations
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	10.3	9.7
Current period provisions	2.9
Write-offs charged against allowance	(2.4)
Recoveries of amounts previously written off	0.1
Corporate and Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Credit Loss	0.8	$ 0.8
Current period provisions	0
Write-offs charged against allowance	0
Recoveries of amounts previously written off	$ 0

Earnings Per Share (Details)

Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Denominator
Basic Average Common Shares Outstanding	392,657	383,062
Dilutive potential common shares
Shares contingently issuable under employee stock plans	630	845
Shares restricted under stock plans	288	207
Forward agreements	337	0
Diluted Average Common Shares	393,912	384,114

Equity (Narrative) (Details)

Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Preferred Stock, Shares Authorized	20,000,000		20,000,000
Preferred Stock, Shares Outstanding	440,000		440,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01
At The Market Program
Common Stock Aggregate Sale Price	$ 750
ATM Program Equity Remaining Available for Issuance	$ 600
Forward February 21 Member
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share	$ 22.48
Forward Contract Indexed to Issuer's Equity, Shares	6,672,740
Forward Contract Indexed to Issuer's Equity, Settlement Alternatives, Shares, at Fair Value	$ 148.5
Forward Contract Indexed to Issuers Equity, Forward Rate Per Share, at Fair Value	$ 22.25
Series A Preferred Stock
Preferred Stock, Shares Outstanding	400,000
Preferred Stock, Amount of Preferred Dividends in Arrears	$ 6.7	$ 6.7
Preferred Stock, Per Share Amounts of Preferred Dividends in Arrears	$ 16.63	$ 16.63
Series B Preferred Stock
Preferred Stock, Shares Outstanding	20,000
Preferred Stock, Amount of Preferred Dividends in Arrears	$ 1.4	$ 1.4
Preferred Stock, Per Share Amounts of Preferred Dividends in Arrears	$ 72.23	$ 72.23
Series B-1 Preferred Stock
Preferred Stock, Shares Outstanding	20,000

Equity Schedule of Stock by Cla

Equity Schedule of Stock by Class - Preferred (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	440,000		440,000
Shares outstanding	$ 5,931.6		$ 5,752.2
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Preferred Stock, Shares Outstanding	400,000
Dividends Declared Per Share	$ 28.25	$ 28.25
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share	$ 25,000
Preferred Stock, Shares Outstanding	20,000
Dividends Declared Per Share	$ 812.50	$ 812.50
Series B-1 Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	20,000
Preferred Stock | Series A Preferred Stock
Class of Stock [Line Items]
Shares outstanding	$ 393.9		393.9
Preferred Stock | Series B Preferred Stock
Class of Stock [Line Items]
Shares outstanding	$ 486.1		$ 486.1

Gas in Storage (Narrative) (Det

Gas in Storage (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Gas in Storage [Abstract]
LIFO Inventory Amount	$ 22.3	$ 0

Property, Plant, and Equipment

Property, Plant, and Equipment (Narrative) (Details) $ in Millions	Mar. 31, 2021USD ($)
Property, Plant and Equipment [Abstract]
Plant and Equipment associated with Schahfer Generating Station Retirement	$ 861.6

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of COVID-19 Regulatory Impact) (Details) $ in Millions	Mar. 31, 2021USD ($)
Incremental O&M - COVID | Columbia Of Ohio
Regulated Operations
Regulatory Assets	$ 2
Incremental O&M - COVID | Columbia Of Virginia
Regulated Operations
Regulatory Assets	0.1
Incremental O&M and Bad Debt - COVID | NIPSCO
Regulated Operations
Regulatory Assets	12
Incremental O&M and Bad Debt - COVID | Columbia Of Maryland
Regulated Operations
Regulatory Assets	1.1
Incremental Bad Debt - COVID | Columbia Of Pennsylvania
Regulated Operations
Regulatory Assets	$ 7.1

Risk Management Activities (Nar

Risk Management Activities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Limit of GCA Volumes	20.00%
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0	$ 0
Minimum
Derivative [Line Items]
Commodity Contract Length	5 years
Maximum
Derivative [Line Items]
Commodity Contract Length	10 years
Interest Rate Swap
Derivative [Line Items]
Derivative, Notional Amount	$ 500

Risk Management Activities (Sch

Risk Management Activities (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Risk Management Assets Current
Derivatives, Fair Value [Line Items]
Risk management assets	$ 1	$ 10.4
Risk Management Assets Noncurrent
Derivatives, Fair Value [Line Items]
Risk management assets	3.2	2.8
Risk Management Liabilities Current
Derivatives, Fair Value [Line Items]
Risk management liabilities	22.1	78.2
Risk Management Liabilities Noncurrent
Derivatives, Fair Value [Line Items]
Risk management liabilities	78.9	144.6
Interest Rate Risk | Risk Management Assets Current
Derivatives, Fair Value [Line Items]
Risk management assets	0	0
Interest Rate Risk | Risk Management Assets Noncurrent
Derivatives, Fair Value [Line Items]
Risk management assets	0	0
Interest Rate Risk | Risk Management Liabilities Current
Derivatives, Fair Value [Line Items]
Risk management liabilities	17.1	70.9
Interest Rate Risk | Risk Management Liabilities Noncurrent
Derivatives, Fair Value [Line Items]
Risk management liabilities	40.6	99.5
Commodity Price Risk Programs | Risk Management Assets Current
Derivatives, Fair Value [Line Items]
Risk management assets	1	10.4
Commodity Price Risk Programs | Risk Management Assets Noncurrent
Derivatives, Fair Value [Line Items]
Risk management assets	3.2	2.8
Commodity Price Risk Programs | Risk Management Liabilities Current
Derivatives, Fair Value [Line Items]
Risk management liabilities	5	7.3
Commodity Price Risk Programs | Risk Management Liabilities Noncurrent
Derivatives, Fair Value [Line Items]
Risk management liabilities	$ 38.3	$ 45.1

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosure [Line Items]
Transfers between Fair Value Hierarchies	$ 0	$ 0
Material Level 3 Changes	0	0
Allowance for Credit Loss	(0.3)	(0.5)
U.S. Treasury debt securities
Fair Value Disclosure [Line Items]
Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value	6.2
Allowance for Credit Loss	0	0
Corporate/Other debt securities
Fair Value Disclosure [Line Items]
Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value	3.9
Allowance for Credit Loss	$ (0.3)	$ (0.5)

Fair Value (Fair Value Of Finan

Fair Value (Fair Value Of Financial Assets And Liabilities Measured On A Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets
Total	$ 172.1	$ 184.1
Liabilities
Total	101	222.8
Fair Value, Inputs, Level 1
Assets
Risk management assets	0	0
Available-for-sale securities	0	0
Total	0	0
Liabilities
Risk management liabilities	0	0
Total	0	0
Significant Other Observable Inputs (Level 2)
Assets
Risk management assets	4.2	13.2
Available-for-sale securities	167.9	170.9
Total	172.1	184.1
Liabilities
Risk management liabilities	101	222.8
Total	101	222.8
Significant Unobservable Inputs (Level 3)
Assets
Risk management assets	0	0
Available-for-sale securities	0	0
Total	0	0
Liabilities
Risk management liabilities	0	0
Total	0	0
Available-for-sale Securities
Assets
Available-for-sale securities	167.9	170.9
Risk management assets
Assets
Risk management assets	4.2	13.2
Liabilities
Risk management liabilities	$ 101	$ 222.8

Fair Value (Available-For-Sale

Fair Value (Available-For-Sale Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosure [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 22.1	$ 0
Amortized Cost	163.8	163.9
Gross Unrealized Gains	5.5	8
Gross Unrealized Losses	(1.1)	(0.5)
Allowance for Credit Loss	(0.3)	(0.5)
Fair Value	167.9	170.9
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	25.7	13.2
U.S. Treasury debt securities
Fair Value Disclosure [Line Items]
Amortized Cost	37.1	33.7
Gross Unrealized Gains	0.2	0.3
Gross Unrealized Losses	(0.3)	0
Allowance for Credit Loss	0	0
Fair Value	37	34
Corporate/Other debt securities
Fair Value Disclosure [Line Items]
Amortized Cost	126.7	130.2
Gross Unrealized Gains	5.3	7.7
Gross Unrealized Losses	(0.8)	(0.5)
Allowance for Credit Loss	(0.3)	(0.5)
Fair Value	$ 130.9	$ 136.9

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Long-term Debt (including current portion), Carrying Amount	$ 9,246.7	$ 9,243.1
Long-term debt (including current portion), Estimated Fair Value	$ 10,178	$ 11,034.2

Transfers Of Financial Assets_2

Transfers Of Financial Assets (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Number of Agreements	3
Cash From Financing Activities Related To The Change In Short-Term Borrowings Due To The Securitization Transactions	$ 0	$ 106.2
Securitization Transaction Fees	0.4	$ 0.7
Accounts Receivable Program
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Seasonal Limit	$ 510

Transfers Of Financial Assets_3

Transfers Of Financial Assets (Schedule Of Gross And Net Receivables Transferred As Well As Short-Term Borrowings Related To The Securitization Transactions) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Gross Receivables	$ 630.8	$ 607.7
Less: Receivables not transferred	630.8	607.7
Net receivables transferred	0	0
Short-term debt due to asset securitization	$ 0	$ 0

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 1,485.9	$ 1,485.9

Goodwill (Schedule of Goodwill)

Goodwill (Schedule of Goodwill) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 1,485.9	$ 1,485.9
Gas Distribution Operations
Goodwill [Line Items]
Goodwill	1,485.9
Electric Operations
Goodwill [Line Items]
Goodwill	0
Corporate and Other
Goodwill [Line Items]
Goodwill	$ 0

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Effective income tax rates	17.40%	(24.50%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	21.00%
Increase (Decrease) in Effective Tax Rate	41.90%
Changes to Liability for Uncertain Tax Positions	$ 0

Pension And Other Postretirem_3

Pension And Other Postretirement Benefits (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0.7
Defined Benefit Plan, Pension Asset, (Increase)Decrease For Remeasurement Due To Settlement	(5.8)
Change in Regulatory Assets Due to Interim Measurement	2.1
Change in Accumulated Other Comprehensive Income Due to Interim Measurement	0.4
Change to Defined Benefit Plan Net Periodic Costs Due to Interim Measurement	4
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 5.1

Pension And Other Postretirem_4

Pension And Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 7.6	$ 8
Interest cost	7.7	13.5
Expected return on assets	(25.8)	(28.4)
Amortization of prior service credit	0	0.2
Recognized actuarial loss	5.3	8.7
Settlement loss	(3.3)	0
Total Net Periodic Benefits Cost	(1.9)	2
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1.5	1.6
Interest cost	2.5	3.9
Expected return on assets	(3.8)	(3.6)
Amortization of prior service credit	(0.6)	(0.5)
Recognized actuarial loss	1.2	1.3
Settlement loss	0	0
Total Net Periodic Benefits Cost	$ 0.8	$ 2.7

Pension And Other Postretirem_5

Pension And Other Postretirement Benefits Schedule of Assumptions Used (Details) - Pension Plan	3 Months Ended
	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.57%
Discount rate- service cost	2.81%
Discount rate - interest cost	1.57%
Expected return on assets	4.80%

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details)	3 Months Ended		4 Months Ended
	Mar. 31, 2021USD ($)RateMW	Mar. 31, 2020USD ($)	Mar. 31, 2021USD ($)RateMW	Dec. 31, 2020USD ($)
Variable Interest Entity [Line Items]
Nameplate Capacity | MW	102		102
Wind Power Purchase Agreement, Purchase Percentage | Rate	100.00%		100.00%
Total Equity Membership Interest	100.00%		100.00%
Additional Obligation to the Developer	$ 6,000,000		$ 6,000,000
Payment to renewable generation asset developer	(7,400,000)	$ 0
Total Obligation to the Developer	75,700,000		75,700,000
Total Contributions	170,100,000		170,100,000
VIE Net Assets	170,000,000		170,000,000	$ 156,400,000
Noncontrolling interest in consolidated subsidiaries	94,100,000		$ 94,100,000	$ 85,600,000
Net income attributable to noncontrolling interest	$ 1,000,000	$ 0
Rosewater Wind Farm
Variable Interest Entity [Line Items]
Wind Power Purchase Agreement, Purchase Percentage | Rate	100.00%		100.00%
NIPSCO
Variable Interest Entity [Line Items]
Cash Contribution	$ 100,000		$ 800,000
Tax Equity Partner
Variable Interest Entity [Line Items]
Cash Contribution	$ 7,500,000		$ 93,600,000

Variable Interest Entities (Sch

Variable Interest Entities (Schedule of VIE Assets and Liabilities) (Details) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Current assets	[1]	$ 1,593.5	$ 1,659.4
Total Assets		22,194.5	22,040.5
Current liabilities		2,258.8	2,279.4
Asset retirement obligations		479.7	477.1
Other noncurrent liabilities		444.5	515.5
Rosewater
Variable Interest Entity [Line Items]
Net Property, Plant and Equipment		174.2	175.6
Current assets		4.2	1.7
Total Assets		178.4	177.3
Current liabilities		2.8	15.3
Asset retirement obligations		5.5	5.5
Other noncurrent liabilities		0.1	0.1
Total liabilities		$ 8.4	$ 20.9
[1]	(1) Includes $174.2 million and $175.6 million of net property, plant and equipment assets and $4.2 million and $1.7 million of current assets of a consolidated VIE as of March 31, 2021 and December 31, 2020 that may be used only to settle obligations of the consolidated VIE. Refer to Note 15 "Variable Interest Entities" for additional information.

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Commercial paper outstanding	$ 520	$ 503
Revolving Credit Facility
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,850
Long-term Line of Credit	0	$ 0
Commercial Paper
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500

Short-Term Borrowings (Schedule

Short-Term Borrowings (Schedule Of Short-Term Borrowings) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Commercial paper weighted-average interest rate of 0.19% and 0.27% at March 31, 2021 and December 31, 2020, respectively	$ 520	$ 503
Total short-term borrowings	$ 520	$ 503
Commercial Paper
Short-term Debt [Line Items]
Short-term Debt, Weighted Average Interest Rate, at Point in Time	0.19%	0.27%

Other Commitments And Conting_3

Other Commitments And Contingencies (Narrative) (Details)	3 Months Ended	4 Months Ended	31 Months Ended
	Mar. 31, 2021USD ($)Rate	Dec. 31, 2018USD ($)	Mar. 31, 2021USD ($)Rate	Dec. 31, 2020USD ($)	Jul. 26, 2019USD ($)
Other Commitments And Contingencies [Line Items]
Guaranty Liabilities	$ 34,000,000		$ 34,000,000
Litigation Settlement, Amount Awarded to Other Party					$ 143,000,000
Recorded reserves to cover environmental remediation at various sites	$ 90,600,000		$ 90,600,000	$ 92,600,000
Wind Power Purchase Agreement, Purchase Percentage | Rate	100.00%		100.00%
Costs Resulting from the Greater Lawrence Incident		$ 1,023,000,000
Restructuring and Related Cost, Expected Cost	$ 40,000,000		$ 40,000,000
Restructuring and Related Cost, Cost Incurred to Date	$ 38,100,000		$ 38,100,000
MGP Sites
Other Commitments And Contingencies [Line Items]
Number of waste disposal sites identified by program	54		54
Liability for Estimated Remediation Costs	$ 84,300,000		$ 84,300,000	85,000,000
Reasonably possible remediation costs variance from reserve	$ 20,000,000		20,000,000
Columbia Of Massachusetts
Other Commitments And Contingencies [Line Items]
Gas Meters Affected	7,500
Businesses Impacted by Incident	700
Plea Agreement Criminal Fine	$ 53,030,116
Pipeline Replacement Expenses			258,000,000
Deferred Tax Assets, Net	50,000,000		50,000,000
Minimum | Columbia Of Massachusetts
Other Commitments And Contingencies [Line Items]
Expenses Related to Third-Party Claims			1,040,000,000
Standby Letters of Credit
Other Commitments And Contingencies [Line Items]
Long-term Line of Credit	$ 15,200,000		$ 15,200,000	$ 15,200,000

Other Commitments And Conting_4

Other Commitments And Contingencies (Restructuring) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 7.3	$ 11.1
Restructuring Reserve, Period Increase (Decrease)	4.6
Payments for Restructuring	(8.4)
Restructuring Reserve, Accrual Adjustment	$ 0

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (156.7)	$ (92.6)
Other Comprehensive Income (Loss) before reclassifications	81	(138.1)
Amounts reclassified from accumulated other comprehensive income (loss)	0.2	0.1
Net current-period other comprehensive income (loss)	81.2	(138)
Ending Balance	(75.5)	(230.6)
Gains and Losses on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	6	3.3
Other Comprehensive Income (Loss) before reclassifications	(2.2)	(5.2)
Amounts reclassified from accumulated other comprehensive income (loss)	(0.3)	(0.2)
Net current-period other comprehensive income (loss)	(2.5)	(5.4)
Ending Balance	3.5	(2.1)
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(147.9)	(77.2)
Other Comprehensive Income (Loss) before reclassifications	84.6	(133.3)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Net current-period other comprehensive income (loss)	84.6	(133.3)
Ending Balance	(63.3)	(210.5)
Pension and OPEB Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(14.8)	(18.7)
Other Comprehensive Income (Loss) before reclassifications	(1.4)	0.4
Amounts reclassified from accumulated other comprehensive income (loss)	0.5	0.3
Net current-period other comprehensive income (loss)	(0.9)	0.7
Ending Balance	$ (15.7)	$ (18)

Other, Net (Details)

Other, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other, Net [Abstract]
Interest income	$ 0.9	$ 1.7
AFUDC equity	1.5	1.7
Pension and other postretirement non-service benefit	8.5	2.7
Miscellaneous	(0.4)	(0.7)
Other, net	$ 10.5	$ 5.4

Business Segment Information (N

Business Segment Information (Narrative) (Details)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Primary business 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
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 1,545.6	$ 1,605.5
Consolidated Operating Income (Loss)	433.2	148.2
Eliminations
Segment Reporting Information [Line Items]
Revenues	(107.2)	(109.9)
Gas Distribution Operations
Segment Reporting Information [Line Items]
Revenues	1,138.9	1,231
Consolidated Operating Income (Loss)	346.9	78.5
Gas Distribution Operations | Unaffiliated
Segment Reporting Information [Line Items]
Revenues	1,135.8	1,228
Gas Distribution Operations | Intersegment
Segment Reporting Information [Line Items]
Revenues	3.1	3
Electric Operations
Segment Reporting Information [Line Items]
Revenues	402.7	377.5
Consolidated Operating Income (Loss)	87.9	78.5
Electric Operations | Unaffiliated
Segment Reporting Information [Line Items]
Revenues	402.5	377.3
Electric Operations | Intersegment
Segment Reporting Information [Line Items]
Revenues	0.2	0.2
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	111.2	106.9
Consolidated Operating Income (Loss)	(1.6)	(8.8)
Corporate and Other | Unaffiliated
Segment Reporting Information [Line Items]
Revenues	7.3	0.2
Corporate and Other | Intersegment
Segment Reporting Information [Line Items]
Revenues	$ 103.9	$ 106.7

Subsequent Event (Narrative) (D

Subsequent Event (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Apr. 19, 2021	Mar. 31, 2021	Dec. 31, 2020
Subsequent Event [Line Items]
Preferred Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01
Subsequent Event | Series C Preferred Stock
Subsequent Event [Line Items]
Undivided Beneficial Ownership Interest, Percent	10.00%
Preferred Stock, Par or Stated Value Per Share	$ 0.01
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Subsequent Event | Series A Corporate Units
Subsequent Event [Line Items]
Stock Issued During Period, Shares, New Issues	8,625
Shares Issued, Price Per Share	$ 100
Net Proceeds from Sale	$ 835.5
Corporate Units Contract Annual Rate	7.75%