Washington Gas Light (WGLCP) 10-Q 30 Apr 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 29, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	0-49807
Entity Registrant Name	WASHINGTON GAS LIGHT CO
Entity Tax Identification Number	53-0162882
Entity Address, Address Line One	1000 Maine Ave., S.W.
Entity Address, City or Town	Washington
Entity Address, Postal Zip Code	20024
City Area Code	703
Local Phone Number	750-4440
Title of 12(g) Security	Common stock, $1.00 par value
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		46,479,536
Entity Central Index Key	0000104819
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Incorporation, State or Country Code	VA
Entity Address, State or Province	DC

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment
At original cost	$ 6,408,122	$ 6,363,392
Accumulated depreciation and amortization	(1,673,419)	(1,668,491)
Net property, plant and equipment	4,734,703	4,694,901
Current Assets
Cash and cash equivalents	11,056	1
Receivables (net of allowance for doubtful accounts of $32,401 and $27,283, respectively)	346,997	339,759
Gas costs and other regulatory assets	20,318	31,376
Materials and supplies—principally at average cost	19,632	20,389
Storage gas	28,971	70,582
Prepaid taxes	17,835	23,547
Other prepayments	27,289	30,980
Receivables from associated companies	4,243	128,254
Derivatives	10,605	5,049
Other	2,278	6,836
Total current assets	489,224	656,773
Regulatory assets
Gas costs	74,174	109,034
Pension and other post-retirement benefits	2,982	3,880
Other	97,468	99,793
Prepaid post-retirement benefits	435,354	433,319
Operating lease right of use asset	39,005	38,097
Derivatives	14,788	11,263
Other	19,071	22,637
Total deferred charges and other assets	682,842	718,023
Total Assets	5,906,769	6,069,697
Capitalization
Common shareholder’s equity	1,965,561	1,855,925
Long-term debt	1,519,986	1,547,202
Total capitalization	3,485,547	3,403,127
Current Liabilities
Notes payable	0	184,953
Accounts payable and other accrued liabilities	223,245	292,454
Customer deposits and advance payments	25,558	38,743
Gas costs and other regulatory liabilities	55,491	72,197
Accrued taxes	26,668	26,637
Payables to associated companies	32,870	29,526
Operating lease liability	5,886	5,734
Derivatives	11,641	7,053
Other	6,269	6,543
Total current liabilities	387,628	663,840
Deferred Credits
Deferred income taxes	695,344	656,876
Accrued pensions and benefits	62,172	65,276
Asset retirement obligations	214,360	212,161
Regulatory liabilities
Accrued asset removal costs	238,713	239,259
Pension and other post-retirement benefits	258,202	262,411
Excess deferred taxes and other	374,972	376,975
Operating lease liability	51,443	50,894
Derivatives	87,624	88,559
Other	50,764	50,319
Total deferred credits	2,033,594	2,002,730
Commitments and Contingencies (Note 9)
Total Capitalization and Liabilities	$ 5,906,769	$ 6,069,697

Condensed Balance Sheets (Una_2

Condensed Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for credit losses	$ 32,401	$ 27,283

Condensed Statements of Operati

Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
OPERATING REVENUES	$ 582,496	$ 501,735
OPERATING EXPENSES
Utility cost of gas	217,005	141,951
Operation and maintenance	99,583	102,678
Depreciation and amortization	36,625	35,870
General taxes and other assessments	55,435	50,069
Total Operating Expenses	408,648	330,568
OPERATING INCOME	173,848	171,167
Other income (expense) — net	9,583	5,332
Interest expense	15,420	16,694
INCOME BEFORE INCOME TAXES	168,011	159,805
INCOME TAX EXPENSE	34,397	32,046
NET INCOME	$ 133,614	$ 127,759

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 133,614	$ 127,759
Pension and other post-retirement benefit plans
Change in prior service cost	(81)	(304)
Change in actuarial net gain	1,470	2,691
Total pension and other post-retirement benefit plans	1,389	2,387
INCOME TAX EXPENSE RELATED TO OTHER COMPREHENSIVE INCOME	367	620
OTHER COMPREHENSIVE INCOME	1,022	1,767
COMPREHENSIVE INCOME	$ 134,636	$ 129,526

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
OPERATING ACTIVITIES
Net income	$ 133,614	$ 127,759
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and amortization	36,625	35,870
Amortization of:
Other regulatory assets and liabilities — net	3,090	2,225
Debt related costs	250	360
Deferred income taxes — net	33,248	32,196
Accrued/deferred pension and other post-retirement benefit cost (benefit)	(6,038)	(1,797)
Compensation expense related to stock-based awards	2,479	446
Provision for doubtful accounts	7,345	5,874
Unrealized (gain) loss on derivative contracts	(5,337)	(6,122)
Other non-cash charges (credits) — net	(71)	(172)
Changes in operating assets and liabilities (Note 14)	136,729	49,043
Net Cash Provided by Operating Activities	341,934	245,682
FINANCING ACTIVITIES
Capital contribution from parent	0	125,000
Net borrowing (repayment) under credit facilities	(212,459)	(253,972)
Dividends on common stock	(25,000)	(25,000)
Other financing activities — net	(164)	0
Net Cash Used in Financing Activities	(237,623)	(153,972)
INVESTING ACTIVITIES
Capital expenditures	(99,308)	(70,995)
Net Cash Used in Investing Activities	(99,308)	(70,995)
INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	5,003	20,715
Cash, Cash Equivalents, and Restricted Cash at Beginning of the Period	21,962	61,148
Cash, Cash equivalents and Restricted Cash at End of the Period	$ 26,965	$ 81,863

Accounting Policies

Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Accounting Policies	ACCOUNTING POLICIES Basis of Presentation Washington Gas is an indirect, wholly owned subsidiary of, among other entities, AltaGas and WGL. Wrangler SPE LLC (Wrangler), a bankruptcy remote, special purpose entity, directly owns the common stock of Washington Gas. Wrangler was formed for the purpose of “ring fencing” Washington Gas, that is removing Washington Gas from the bankruptcy estate of AltaGas and its affiliates in the event that any parent or affiliate entity becomes the subject of bankruptcy or insolvency proceedings. Wrangler is the wholly owned subsidiary of WGL and AltaGas. The condensed financial statements of Washington Gas have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Therefore, certain financial information and note disclosures accompanying annual financial statements prepared in accordance with generally accepted accounting principles in the United States of America (GAAP) are omitted in this interim report. The interim condensed financial statements and accompanying notes should be read in conjunction with the Financial Statements on Form 10-K for the year ended December 31, 2020. Due to the seasonal nature of our business, the results of operations for the periods presented in this report are not necessarily indicative of actual results for the full years ending December 31, 2021 and 2020. The information presented in this report on Form 10-Q are presented solely for the registrant Washington Gas on a stand-alone basis. The accompanying unaudited condensed financial statements for Washington Gas reflect all normal recurring adjustments that are necessary, in our opinion, to present fairly the results of operations in accordance with GAAP. For a complete description of our significant accounting policies, refer to Note 1 — Accounting Policies of the Notes to Financial Statements on Form 10-K for the fiscal year ended December 31, 2020. We include herein certain updates to those policies. Change in Accounting Principle In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the market-related value of assets (MRVA) used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. The following tables summarize the effect of the change in accounting principle on the primary financial statement line items on our condensed statements of operations, condensed statements of comprehensive income, and condensed statements of cash flows. The following Notes have been impacted by the change: Note 7 — Components of Total Equity , Note 8 — Pension and Other Post — Retirement Benefit Plans, and Note 13 — Accumulated Other Comprehensive Income . Three Months Ended March 31, 2020 (In thousands) As Previously Reported Adjustment As Adjusted Condensed Statements of Operations Other income (expense) — net $ 3,070 $ 2,262 $ 5,332 Income tax expense $ 31,459 $ 587 $ 32,046 Net income $ 126,084 $ 1,675 $ 127,759 Condensed Statements of Comprehensive Income Other comprehensive income $ 1,941 $ (174) $ 1,767 Comprehensive income $ 128,025 $ 1,501 $ 129,526 Condensed Statements of Cash Flows Net income $ 126,084 $ 1,675 $ 127,759 ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES Accrued/deferred pension and other post-retirement benefit cost (benefit) $ 465 $ (2,262) $ (1,797) Deferred income taxes — net $ 31,609 $ 587 $ 32,196 Accounting Standards Adopted in the Calendar Year and Other Newly Issued Accounting Standards The following table represents accounting standards adopted by Washington Gas during the three months ended March 31, 2021. ACCOUNTING STANDARDS ADOPTED IN CALENDAR YEAR 2021 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2019-12, Income Taxes (Topic 740) Simplifying the Accounting for Income Taxes As part of FASB's Simplification Initiative, this standard amends ASC Topic 740 by removing certain exceptions to the general principles and clarifying and amending other current guidance. Early adoption is permitted. January 1, 2021 The adoption of this standard did not have a material effect on our financial statements. ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting, including other subsequent ASUs further amending and clarifying the guidance. This standard provides optional expedients and exceptions to ease the potential accounting burden associated with transitioning away from reference rates that are expected to be discontinued. The amendments may be elected prospectively to contract modifications and hedging relationships existing on or after the date of adoption and through December 31, 2022. January 1, 2021 Currently, our credit facilities and carrying charges in certain commodity sale arrangements, reference LIBOR. The discontinuation of LIBOR will require these arrangements to be modified to an alternative interest rate. The majority of our credit facilities include fallback provisions that contemplate the replacement of LIBOR. The Company has made a policy election to adopt the optional expedients related to contract modifications related to its debt and certain other arrangements and will apply the relief on a prospective basis as modifications are made. The Company continues to monitor the activities of regulators and financial institutions to transition to an alternative reference rate, and also continues to review additional arrangements for references to LIBOR. Accordingly, the Company may make additional optional elections in the future. ASU 2020-10, Codification Improvements The amendments in this ASU provide clarification and improve the codification in recently issued accounting standards. January 1, 2021 The adoption of this standard did not have a material effect on our financial statements.

Credit Losses

Credit Losses	3 Months Ended
	Mar. 31, 2021
Credit Loss [Abstract]
Credit Losses	CREDIT LOSSES On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (CECL) model. The measurement of expected credit losses under the CECL model is applicable to financial assets measured at amortized cost and off-balance sheet credit exposures. Our assessment concluded that our cash equivalents, accounts receivables, unbilled revenue, contract assets, and receivables from our trading partners that is part of a collaborative arrangement are within scope of the new standard. We adopted the standard using a modified-retrospective approach through a cumulative-effect adjustment to retained earnings at January 1, 2020. Upon implementation of ASU 2016-13, we recorded a $1.5 million increase to the Company's allowance for doubtful accounts and a decrease to retained earnings. Washington Gas also elected to account for its cash equivalents at fair value. Customer Receivables: Washington Gas is exposed to customer credit risk resulting from the non-payment of utility bills. To manage this customer credit risk, Washington Gas customers are offered budget billing options or higher risk customers may be required to provide a cash deposit until the requirement for deposit refunds are met. Washington Gas can recover a portion of non-payments from customers in future periods through the rate-setting process. For accounts receivable and unbilled revenue generated by the utility business, an allowance for doubtful accounts is recognized using a historical loss-rate based on historical payment and collection experience. This rate may be adjusted based on management’s expectations of unusual macroeconomic conditions and other factors. Washington Gas regularly evaluates the reasonableness of the allowance based on a combination of factors, such as the length of time receivables are past due, historical expected payment, collection experience, financial condition of customers, and other circumstances that could impact customers' ability or desire to make payments. Based on previous collection experience, Washington Gas has not recorded an allowance for doubtful accounts for its contract assets associated with our energy management services projects with the federal government. Refer to Note 12 — Related Party Transactions for further information. Washington Gas Asset Optimization : Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources by entering into physical and financial transactions in the form of forwards, futures and option contracts for periods when these resources are not being used to physically serve utility customers. Refer to Note 10 — Derivatives for further discussion of asset optimization program. Washington Gas operates under an existing wholesale counterparty credit policy that is designed to mitigate credit risk. Credit limits are established for each counterparty and credit enhancements such as letters of credit, parent guarantees and cash collateral maybe required. The creditworthiness of all counterparties is continuously monitored. The allowance for doubtful accounts is estimated by applying 30-year historical default rates for one-year receivables sourced from external credit rating agencies to the accounts receivable and unbilled revenue balances associated with counterparties Washington Gas has determined to be below investment grade. In the event that a counterparty no longer exhibits similar risk characteristics, the associated receivable is evaluated individually. COVID-19 : The COVID-19 pandemic has resulted in widespread challenges to businesses and the job market since 2020. The increased unemployment rate has impacted the ability of the Company’s customers to pay for services. As a result of regulatory orders, we temporarily suspended customer disconnections for non-payment, temporarily suspended collection activities and temporarily waived assessing and billing late payment fees. While the suspension of disconnections has been lifted in Maryland for customers effective April 1, 2021, the suspension in District of Columbia and Virginia continues. We resumed assessing late payment fees in Maryland in October 2020 following a regulatory order. The suspension of collection activities has caused our overall accounts receivable portfolio to age more than historical levels. However, we do not expect the increase in credit losses to have a significant impact on net income. In addition, the Public Service Commission of the District of Columbia (PSC of DC), the Maryland Public Service Commission (PSC of MD) and the Commonwealth of Virginia State Corporation Commission (SCC of VA) each issued an Order authorizing Washington Gas to establish a regulatory asset to capture and track the incremental COVID-19 related costs. In December 2020, Washington Gas received $7.7 million of Coronavirus Relief Funds from SCC of VA to provide direct assistance to Virginia customers with balances over 30 days in arrears. Virginia customers need to meet the criteria established by the program to be eligible to receive the funds. Any unused funds will be returned to the SCC of VA. At March 31, 2021, $5.4 million of unused funds remained in "Gas costs due to customer" on Washington Gas' condensed balance sheets. Considering the Virginia Coronavirus Relief Funds, Washington Gas has recorded a total o f $6.3 million in deferrals of incremental bad debt expense to COVID-19 regulatory assets across all three jurisdictions at March 31, 2021. As of March 31, 2021, we have evaluated the adequacy of our allowance for credit losses in light of the suspension of shut-offs for nonpayment due to COVID-19 and the economic downturn. Our evaluation included an analysis of customer payment trends, economic conditions, receivables aging, considerations of past economic downturns, the actions the company is taking to assist customers with past due balances, and other stimulus programs, and customer account write-offs. In addition, we considered benefits available under government COVID-19 relief programs. Based on this evaluation, we have concluded that the allowance for credit losses as of March 31, 2021 adequately reflected the collection risk and net realizable value for our receivables. We will continue to monitor changing circumstances and will adjust our allowance for credit losses as additional information becomes available. The following table presents the activity of allowance for doubtful accounts by types for the reporting periods. Three Months Ended Three Months Ended (In millions) Account Receivables and Unbilled Revenue Asset Optimization Account Receivables and Unbilled Revenue Asset Optimization Balance, beginning of period $ 27.3 $ 0.1 $ 18.7 $ — Provision 7.5 (0.1) 5.9 — Write offs (2.8) — (7.5) — Recoveries 0.4 — 0.3 — Adjustment upon adoption of ASC 326 — — 1.4 0.1 Balance, end of period $ 32.4 $ — $ 18.8 $ 0.1

Revenue from Contracts With Cus

Revenue from Contracts With Customers	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	REVENUE FROM CONTRACTS WITH CUSTOMERS The Company recognizes revenue from contracts with customers when the obligation to customers is satisfied and at an amount it expects to be received in exchange for those goods or services. Washington Gas sells natural gas and distribution services to residential, commercial, industrial and governmental customers through regulated tariff rates approved by regulatory commissions in the jurisdictions where it operates. Customers are billed monthly based on regular meter readings. Customer billings are based on two main components: (i) a fixed service fee and (ii) a variable fee based on usage. For customers who choose to purchase their natural gas from Washington Gas, the bill will include a usage based charge for the cost of the commodity. Revenue is recognized over time as natural gas is delivered or as service is performed. Since meter readings are performed on a cycle basis, Washington Gas recognizes accrued revenue for any services rendered to its customers but not billed at month-end. The tariff sales are generally considered daily or “at-will” contracts as customers may cancel their service at any time (subject to notification requirements in the tariff), and revenue generally represents the amount Washington Gas is entitled to invoice. There are certain contracts that have terms of one year or longer. For these contracts, revenue is recognized based on the amount Washington Gas is entitled to bill the customer. Customers have the choice to purchase natural gas from competitive service providers. Washington Gas charges the competitive service providers balancing fees to manage the natural gas transportation imbalances. Where regulations require, Washington Gas issues customers a consolidated bill to include the natural gas supplied by the competitive service providers and distribution of natural gas. Washington Gas recognizes revenue only for distribution services that it has provided to the customer, and the balancing fees for the services provided to the competitive service provider. The following table disaggregates revenue by type of service for the periods. Disaggregated Revenue by Type of Service Three Months Ended March 31, (In millions) 2021 2020 Revenue from contracts with customers Gas and transportation sales Gas sold and delivered $ 442.6 $ 346.3 Gas delivered for others 102.9 97.6 Other 12.8 13.7 Other revenues 0.9 0.7 Total revenue from contracts with customers $ 559.2 $ 458.3 Other sources of revenue Revenue from alternative revenue programs (a) $ 21.6 $ 40.6 Other (b) 1.7 2.8 Total revenue from other sources $ 23.3 $ 43.4 Total Operating Revenue $ 582.5 $ 501.7 (a) Washington Gas has determined that its Revenue Normalization Adjustment (RNA), Weather Normalization Adjustment (WNA), and Conservation and Ratemaking Efficiency (CARE) Ratemaking Adjustment (CRA) billing adjustment mechanisms and accelerated pipe replacement programs are alternative revenue programs and accounted for under ASC Topic 980. (b) The amount includes late fees billed. The decreases from prior periods were primarily caused by not billing of late payment fees due to COVID-19 as required by regulatory orders. Washington Gas accrues unbilled revenues for gas delivered, but not yet billed at the end of each accounting period due to our customer billing cycles. Unbilled revenues of $86.8 million and $112.7 million are included within "Receivables" on Washington Gas' balance sheets at March 31, 2021 and December 31, 2020, respectively. Unbilled revenues represent performance obligations that have been satisfied and to which Washington Gas has an unconditional right to payment, except for contract assets related to Washington Gas’ area-wide contract, which requires project acceptance by the federal government for the right to payment to occur (refer to Project Financing in Note 12 — Related party transactions for further discussion of Washington Gas’s area-wide contract). Washington Gas did not have any contract liabilities at March 31, 2021 and December 31, 2020. The Company does not have transaction price amounts allocated to future performance obligations. The Company applies the practical expedient available under ASC Topic 606 and does not disclose information about the remaining performance obligations for (i) contracts with an original expected length of one year or less, (ii) contracts for which revenue is recognized at the amount to which the Company has the right to invoice for performance completed, and (iii) contracts with variable consideration that is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct good or service that forms part of a single performance obligation. The following table shows the beginning and ending balances of contract assets from contracts with customers for the reporting periods, which were included within "Receivables" on Washington Gas' condensed balance sheets. (In millions) 2021 2020 Contract assets at January 1 $ 16.1 $ 44.2 Contract assets at March 31 $ 6.7 $ 46.1 Increase (decrease) in contract assets (a) $ (9.4) $ 1.9 ( a) Decrease in 2021 reflected projects accepted by federal government offset to the contract asset was a reduction to "Payable to associated companies".

Accounts Payable and Other Accr

Accounts Payable and Other Accrued Liabilities	3 Months Ended
	Mar. 31, 2021
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable and Other Accrued Liabilities	ACCOUNTS PAYABLE AND OTHER ACCRUED LIABILITIES The table below provides details for the amounts included in “Accounts payable and other accrued liabilities” on the balance sheets. (In millions) March 31, 2021 December 31, 2020 Accounts payable—trade $ 168.7 $ 201.2 Employee benefits and payroll accruals 10.2 22.3 Wages payable 20.8 19.5 Accrued interest 3.4 18.4 Other accrued liabilities (a) 20.1 31.1 Total $ 223.2 $ 292.5 (a) Amount at December 31, 2020 included $12.5 million liability associated with the Antero judgment which was paid in February 2021.

Short-Term Debt

Short-Term Debt	3 Months Ended
	Mar. 31, 2021
Short-term Debt [Abstract]
Short-Term Debt	SHORT-TERM DEBT Washington Gas satisfies the short-term financing requirements through the sale of commercial paper, or through bank borrowings. Due to the seasonal nature of our operations, short-term financing requirements can vary significantly during the year. Revolving credit agreements are maintained to support outstanding commercial paper and to permit short-term borrowing flexibility. The policy of Washington Gas is to maintain bank credit facilities in amounts equal to or greater than the expected maximum commercial paper position. Credit Facility The following is a summary of committed credit available at March 31, 2021 and December 31, 2020. Committed Credit Available (In millions) March 31, 2021 December 31, 2020 Committed credit agreements Unsecured revolving credit facility, expires July 19, 2024 (a) $450.0 $450.0 Less: Commercial Paper outstanding (b) (72.5) (285.0) Net committed credit available $377.5 $165.0 Weighted average interest rate 0.23% 0.31% (a) Washington Gas has the right to request extensions with the bank group 's approval. Washington Gas’ revolving credit facility permits it to borrow an additional $100.0 million, with the bank groups' approval, for a total potential maximum borrowing of $550.0 million. (b) The amount represents principal amount of commercial paper. At March 31, 2021 and December 31, 2020, there were no outstanding bank loans from Washington Gas’ revolving credit facilities. Commercial Paper The total commercial paper carrying value at March 31, 2021 was $72.5 million and was classified as a "Long-term debt" on Washington Gas' condensed balance sheets due to its ability and intent to refinance these balances on a long-term basis.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Long-Term Debt	LONG-TERM DEBT Washington Gas issues unsecured long-term debt in the form of medium-term notes (MTNs) and private placement notes with individual terms regarding interest rates, maturities and call or put options. In addition, Washington Gas classifies certain commercial paper balance as "Long-term debt" due to its ability and intent to refinance these balances on a long-term basis. The following table shows the long-term debt outstanding at March 31, 2021 and December 31, 2020. Long Term Debt Outstanding (In millions) March 31, 2021 December 31, 2020 Washington Gas Unsecured Notes (a) $ 1,446.0 $ 1,446.0 Commercial Paper 72.5 100.0 Total Principal Amounts of Long-Term Debt $ 1,518.5 $ 1,546.0 Unamortized premium (discount) 12.3 12.5 Unamortized debt expense (11.5) (11.6) Non-current finance lease liability 0.7 0.3 Total Carrying Amount of Long-Term Debt $ 1,520.0 $ 1,547.2 Weighted average interest rate (b) 4.46 % 4.46 % (a) Includes MTNs and private placement notes. The amount represents face value of Washington Gas' unsecured notes. (b) Weighted average interest rate is for the Washington Gas unsecured notes. There were no issuances or retirements of unsecured notes for the three months ended March 31, 2021 and 2020.

Components of Total Equity

Components of Total Equity	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Components of Total Equity	COMPONENTS OF TOTAL EQUITY Common Stock Paid-In Capital Retained Earnings (b) Accumulated Other Comprehensive Income, Net of Taxes (b) (In thousands, except shares) Shares Amount Total (b) Three Months Ended March 31, 2021 Balance at December 31, 2020 46,479,536 $ 46,479 $ 1,204,273 $ 603,596 $ 1,577 $ 1,855,925 Net income — — — 133,614 — 133,614 Other comprehensive income — — — — 1,022 1,022 Capital contribution from parent — — — — — — Common stock dividends declared — — — (25,000) — (25,000) Balance at March 31, 2021 46,479,536 $ 46,479 $ 1,204,273 $ 712,210 $ 2,599 $ 1,965,561 Three Months Ended March 31, 2020 Balance at December 31, 2019 46,479,536 $ 46,479 $ 979,273 $ 548,264 $ 4,576 $ 1,578,592 Net income — — — 127,759 — 127,759 Other comprehensive income — — — — 1,767 1,767 Capital contribution from parent — — 125,000 — — 125,000 ASU 2016-13 implementation (a) — — — (1,543) — (1,543) Common stock dividends declared — — — (25,000) — (25,000) Balance at March 31, 2020 46,479,536 $ 46,479 $ 1,104,273 $ 649,480 $ 6,343 $ 1,806,575 (a) Due to implementation of ASU 2016-13 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, see Note 2 — Credit Losses for further information. (b) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the MRVA used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. Refer to Note 1 — Accounting Policies for further discussion.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefit Plans	3 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Pension and Other Post-Retirement Benefit Plans	PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS The following table shows the components of the net periodic benefit costs (income) recognized in our financial statements. Components of Net Periodic Benefit Costs (Income) (b) Three Months Ended March 31, 2021 2020 (a) (In millions) Pension Benefits Health and Life Benefits Pension Health and Life Benefits Service cost $ 3.1 $ 1.6 $ 3.2 $ 1.3 Interest cost 7.6 2.0 8.9 2.3 Expected return on plan assets (10.7) (5.7) (10.8) (5.9) Recognized prior service cost (credit) 0.1 (3.4) 0.1 (3.4) Recognized actuarial loss (gain) 0.3 (1.2) 2.4 (0.5) Settlement charge 1.0 — 1.1 — Net periodic benefit cost (income) 1.4 (6.7) 4.9 (6.2) Allocation to affiliates — 0.2 (0.3) 0.4 Adjusted net periodic benefit cost (income) 1.4 (6.5) 4.6 (5.8) Amount allocated to construction projects (0.6) (0.3) (0.4) (0.2) Amount charged (credited) to expense $ 0.8 $ (6.8) $ 4.2 $ (6.0) (a) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the MRVA used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. Refer to Note 1 — Accounting Policies for further discussion. (b) The other components of net benefit cost are presented separately from service cost and recorded in “Other income (expense)-net” on the accompanying statements of operations . At March 31, 2021 and December 31, 2020, the rabbi trust balance associated with the DB SERP and defined benefit restoration plan (DB restoration) plans were $12.7 million and $18.8 million, respectively. $2.1 million and $10.6 million were recorded in “Current Assets-Other” and “Deferred Charges and Other Assets - Other” on Washington Gas' balance sheets at March 31, 2021; $6.7 million and $12.1 million were recorded in “Current Assets-Other” and “Deferred Charges and Other Assets - Other” at December 31, 2020, respectively, along with other rabbi trust balances.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Commitments Washington Gas has certain natural gas contracts incurred in the normal course of business that require fixed and determinable payments in the future, including unconditional purchase obligations for pipeline capacity, transportation and storage services. There were no significant changes to contractual obligations that are out of the ordinary course of business during the three months ended March 31, 2021. Merger Commitments In connection with the Merger in 2018, Washington Gas and AltaGas have made commitments related to the terms of the PSC of DC settlement agreement and the conditions of approval from the PSC of MD and the SCC of VA. Among other things, these commitments included rate credits distributable to both residential and non-residential customers, gas expansion and other programs, various public interest commitments, and safety programs. As of March 31, 2021, the remaining unpaid amount for the previously accrued merger commitments was $9.4 million. In addition, there are certain additional regulatory commitments that were and will be expensed as the costs are incurred, including the hiring of damage prevention trainers in each jurisdiction for a total of $2.4 million over 5 years; investing up to $70.0 million over a 10-year period to further extend natural gas service; and spending $8.0 million for leak mitigation within 3 years after the Merger close which has been paid as of December 31, 2020. Additionally, there are a number of operational commitments that have an impact on the ongoing business of Washington Gas, including reductions of leak backlogs, conducting a root cause analysis related to customer service, increasing supplier diversity, achieving synergy savings benefits, developing protocols for moving meters from inside to outside customers’ premises, as well as reporting and tracking related to all the commitments. Contingencies We account for contingent liabilities utilizing ASC Topic 450, Contingencies. By their nature, the amount of the contingency and the timing of a contingent event and any resulting accounting recognition are subject to our judgment of such events and our estimates of the amounts. Actual results related to contingencies may be difficult to predict and could differ significantly from the estimates included in reported earnings. Regulatory Contingencies Certain legal and administrative proceedings incidental to our business, including regulatory contingencies, involve Washington Gas. In our opinion, we have recorded an adequate provision for probable losses or refunds to customers for regulatory contingencies related to these proceedings. Environmental Matters We are subject to federal, state and local laws and regulations related to environmental matters. These laws and regulations may require expenditures over a long time frame to control environmental effects. Almost all of the environmental liabilities we have recorded are for costs expected to be incurred to remediate sites where we or a predecessor affiliate operated manufactured gas plants (MGPs). Washington Gas has identified up to ten sites where it or its predecessors may have operated MGPs. Washington Gas last used any such plant in 1984. In connection with these operations, we are aware that coal tar and certain other by-products of the gas manufacturing process are present at or near some former sites and may be present at others. At March 31, 2021 and December 31, 2020, Washington Gas reported a liability of $10.2 million and $10.3 million, respectively, on an undiscounted basis related to future environmental response costs. These estimates principally include the minimum liabilities associated with a range of environmental response costs expected to be incurred. At both March 31, 2021 and December 31, 2020, Washington Gas estimated the maximum liability associated with all of its sites to be approximately $30.6 million. The maximum liability at March 31, 2021 included $19.1 million related to the Anacostia river study and $8.0 million related to the East Station property, which are further discussed below. The estimates were determined by Washington Gas’ environmental experts, based on experience in remediating MGP sites and advice from legal counsel and environmental consultants. The variation between the recorded and estimated maximum liability primarily results from differences in the number of expected years that will be required to perform environmental response processes and the extent of remediation that may be required. Washington Gas is currently remediating its East Station property, located adjacent to the Anacostia River in Washington D.C., including ground water pump and treat, tar recovery, soil encapsulation and other treatment. Under a 2012 consent decree with the District of Columbia and the federal government, Washington Gas is also conducting a remedial investigation and feasibility study on an adjacent property owned by the District of Columbia. The Draft Remedial Investigation Report was submitted to the National Park Service (NPS) and the Department of Energy and Environment (DOEE) on June 12, 2020. Additional remediation may be required at this property. In addition, at another adjoining property known as the “Boat Club Property,” located to the east of the property owned by the District of Columbia, Washington Gas agreed to perform a site investigation and report the findings pursuant to oversight by the District of Columbia DOEE. This property was subject to a July 12, 2019, Administrative Order from the DOEE. That Administrative Order was withdrawn and the Company entered into a negotiated Administrative Order on Consent with the DOEE that was effective on March 11, 2020. Under the terms of the Administrative Order on Consent, the Company submitted a Remedial Investigative Report on February 26, 2021. On March 11, 2021, the Company received an Administrative Order related to the alleged presence of sheens in the Anacostia River. The Company filed an appeal of the Administrative Order with the District of Columbia Office of Administrative Hearings on March 26, 2021. The appeal is pending. Washington Gas received a letter in February 2016 from the DOEE and National Park Service regarding the Anacostia River Sediment Project, indicating that the District of Columbia is conducting a separate remedial investigation and feasibility study of the river to determine if and what cleanup measures may be required and to prepare a natural resource damage assessment. On December 27, 2019, DOEE issued an Anacostia River Sediment Project Proposed Plan, a River-wide Feasibility Study, and supporting documents for public comment. Although the Proposed Plan identifies East Station as one of fifteen potential environmental cleanup sites, DOEE is proposing to continue the remediation of East Station under Washington Gas’ existing Consent Decree rather than as part of the Anacostia River Sediment Project. DOEE issued an Interim Record of Decision for remediation of “Early Action Areas” (that do not include East Station) in the Anacostia River by September 30, 2020. On January 6, 2021, the Company received a supplement to a September 2017 information request from DOEE and the National Park Service regarding its East Station property. We are not able to estimate the total amount of potential costs or timing associated with the District of Columbia’s environmental investigation on the Anacostia River at this time. While an allocation method has not been established, Washington Gas has accrued an amount for estimated study costs based on a potential range of estimates. Regulatory orders issued by the PSC of MD allow Washington Gas to recover the costs associated with the sites applicable to Maryland over the period ending in 2035. Regulatory orders issued by the PSC of DC allow Washington Gas a three-year recovery of prudently incurred environmental response costs and allow Washington Gas to defer additional costs incurred between rate cases. Regulatory orders from the SCC of VA have generally allowed the recovery of prudent environmental remediation costs to the extent they were included in the underlying financial data supporting an application for rate change. At March 31, 2021 and December 31, 2020, Washington Gas reported a regulatory asset of $7.2 million and $7.4 million, respectively, for the portion of environmental response costs that are expected to be recoverable in future rates.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVES Washington Gas enters into contracts that qualify as derivative instruments and are accounted for under ASC Topic 815. These derivative instruments are recorded at fair value on our balance sheets and Washington Gas does not currently designate any derivatives as hedges under ASC Topic 815. Washington Gas’ derivative instruments relate to: (i) Washington Gas’ asset optimization program; (ii) managing price risk associated with the purchase of gas to serve utility customers and (iii) managing interest rate risk. Asset Optimization. Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources during periods when these resources are not being used to physically serve utility customers. Specifically, Washington Gas utilizes its transportation capacity assets to benefit from favorable natural gas prices between different geographic locations and utilizes its storage capacity assets to benefit from favorable natural gas prices between different time periods. As part of this asset optimization program, Washington Gas enters into physical and financial derivative transactions in the form of forward, futures and option contracts with the primary objective of securing operating margins that Washington Gas will ultimately realize. The derivative transactions entered into under this program are subject to mark-to-market accounting treatment under ASC Topic 820. Regulatory sharing mechanisms provide for the annual realized profit from these transactions to be shared between Washington Gas’ shareholder and customers; therefore, changes in fair value are recorded through earnings, or as regulatory assets or liabilities to the extent that it is probable that realized gains and losses associated with these derivative transactions will be included in the rates charged to customers when they are realized. Unrealized gains and losses recorded to earnings may cause significant period-to-period volatility; this volatility does not change the operating margins that Washington Gas expects to ultimately realize from these transactions through the use of its storage and transportation capacity resources. Washington Gas has a collaborative arrangement with a third party to facilitate the asset optimization program. The collaborative arrangement allocates a tiered percentage of profits or losses to the third party as compensation for its participation. The costs recorded by Washington Gas related to the collaborative arrangement totaled $1.3 million and $1.0 million for the three months ended March 31, 2021 and 2020, respectively. These amounts were recorded in “Utility cost of gas” on Washington Gas’ statements of operations. Either party may terminate the collaborative arrangement through the delivery of a termination notice. In such an event, Washington Gas may make a payment upon termination. The following table presents the net margin recorded to “Utility cost of gas” after sharing and management fees associated with our asset optimization transactions. Net Margins for Asset Optimization (In millions) Three Months Ended March 31, 2021 2020 Realized gain $ 2.9 $ 2.3 Unrealized gain 5.3 6.1 Net margin gain $ 8.2 $ 8.4 Managing Price Risk. To manage price risk associated with acquiring natural gas supply for utility customers, Washington Gas enters into physical and financial derivative transactions in the form of forward, option and other contracts, as authorized by its regulators. Any gains and losses associated with these derivatives are recorded as regulatory liabilities or assets, respectively, to reflect the rate treatment for these economic hedging activities. Notional Summary The following table presents notional amounts of our outstanding derivatives at March 31, 2021 and December 31, 2020. Absolute Notional Amounts of Open Positions on Derivative Instruments March 31, 2021 December 31, 2020 Natural Gas (In millions of therms) Asset optimization & trading 10,353.0 10,471.0 Other risk-management activities 794.0 881.0 Location, Fair Value and Offsetting of Derivative Assets and Liabilities Recognized in the Balance Sheets The following table presents the balance sheet line items where derivatives are recognized. Washington Gas has elected to offset the fair value of recognized derivative instruments against the right to reclaim or the obligation to return collateral for derivative instruments executed under the same master netting arrangement in accordance with ASC Topic 815. All recognized derivative contracts and associated financial collateral subject to a master netting arrangement or similar that is eligible for offset under ASC Topic 815 have been presented net in the balance sheets. Balance Sheet Classification of Derivative Instruments (In millions) Gross amounts Gross amounts Netting of Net amounts March 31, 2021 Derivative assets (a) $ 25.8 $ (0.4) $ — $ 25.4 Derivative liabilities (b) (99.6) 0.4 — $ (99.2) Net derivative assets (liabilities) $ (73.8) $ — $ — $ (73.8) December 31, 2020 Derivative assets (a) $ 17.8 $ (1.5) $ — $ 16.3 Derivative liabilities (b) (98.8) 1.5 1.6 (95.7) Net derivative assets (liabilities) $ (81.0) $ — $ 1.6 $ (79.4) (a) Derivative assets at March 31, 2021 include $10.6 million recorded in "Current assets — Derivatives" and $14.8 million in" Deferred charges and other assets — Derivatives" on Washington Gas' balance sheets; Derivative assets at December 31, 2020 include $5.0 million recorded in "Current assets —Derivatives" and $11.3 million in" Deferred charges and other assets — Derivatives" on Washington Gas' condensed balance sheets. (b) Derivative liabilities at March 31, 2021 include $11.6 million recorded in "Current liabilities — Derivatives " and $87.6 million recorded in " Deferred credits — Derivatives" on Washington Gas' balance sheets; Derivative liabilities at December 31, 2020 include $7.1 million recorded in "Current liabilities — Derivatives " and $88.6 million recorded in " Deferred credits — Derivatives" on Washington Gas' condensed balance sheets. Gains and (Losses) on Derivatives The following tables present all gains and losses associated with derivative instruments for the three months ended March 31, 2021 and 2020. Gains and (Losses) on Derivative Instruments (In millions) Three Months Ended March 31, 2021 2020 Recorded to income-Utility cost of gas $ 0.7 $ 3.1 Recorded to regulatory assets-Gas costs (8.0) 8.9 Total $ (7.3) $ 12.0 Collateral Washington Gas utilizes standardized master netting agreements, which facilitate the netting of cash flows into a single net exposure for a given counterparty. As part of these master netting agreements, cash, letters of credit and parent company guarantees may be required to be posted or obtained from counterparties in order to mitigate credit risk related to both derivatives and non-derivative positions. Under Washington Gas’ offsetting policy, collateral balances are offset against the related counterparties’ derivative positions to the extent the application would not result in the over-collateralization of those derivative positions on the balance sheets. Any collateral posted that is not offset against derivative assets and liabilities is included in “Other prepayments” on the balance sheets. Collateral received and not offset against derivative assets and liabilities is included in “Customer deposits and advance payments” on the accompanying balance sheets. At March 31, 2021 and December 31, 2020, Washington Gas had $3.1 million and $2.8 million, respectively, in collateral deposits posted with counterparties that are not offset against derivative asset and liabilities. At March 31, 2021 and December 31, 2020, Washington Gas had $0.1 million and $0.2 million, respectively, cash collateral held representing an obligation, and are not offset against derivative asset and liabilities. Certain derivative instruments of Washington Gas contain contract provisions that require collateral to be posted if the credit rating of Washington Gas falls below certain levels or if counterparty exposure to Washington Gas exceeds a certain level (credit-related contingent features). At March 31, 2021 and December 31, 2020, Washington Gas w as not re quired to post collateral related to a derivative liability that contained a credit-related contingent feature. The following table shows the aggregate fair value of all derivative instruments with credit-related contingent features that are in a liability position, as well as the maximum amount of collateral that would be required if the most intrusive credit-risk-related contingent features underlying these agreements were triggered on March 31, 2021 and December 31, 2020, respectively. Potential Collateral Requirements for Derivative Liabilities (In millions) March 31, 2021 December 31, 2020 Derivative liabilities with credit-risk-contingent features $ 0.1 $ 0.7 Maximum potential collateral requirements $ 0.1 $ 0.6 We do not enter into derivative contracts for speculative purposes. Concentration of Credit Risk We are exposed to credit risk from derivative instruments with wholesale counterparties, which is represented by the fair value of these instruments at the reporting date. We actively monitor and work to minimize counterparty concentration risk through various practices. At March 31, 2021, three counterparties represented over 10% of Washington Gas’ credit exposure to wholesale derivative counterparties for a total credit risk of $32.6 million.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS We measure the fair value of our financial assets and liabilities using a combination of the income and market approaches in accordance with ASC Topic 820. These financial assets and liabilities primarily consist of derivatives recorded on our balance sheets under ASC Topic 815 and short-term investments, other long-term receivable, commercial paper and long-term debt outstanding required to be disclosed at fair value. Under ASC Topic 820, fair value is defined as the exit price, representing the amount that would be received in the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. To value our financial instruments, we use market data or assumptions that market participants would use, including assumptions about credit risk (both our own credit risk and the counterparty’s credit risk) and the risks inherent in the inputs to valuation. We enter into derivative contracts in the futures and over-the-counter (OTC) wholesale and retail markets. These markets are the principal markets for the respective wholesale and retail contracts. Our relevant market participants are our existing counterparties and others who have participated in energy transactions at our delivery points. These participants have access to the same market data as Washington Gas. Valuations are generally based on pricing service data or indicative broker quotes depending on the market location. We measure the net credit exposure at the counterparty level where the right to set-off exists. The net exposure is determined using the mark-to-market exposure adjusted for collateral, letters of credit and parent guarantees. We use published default rates from Standard & Poor’s Ratings Services and Moody’s Investors Service as inputs for determining credit adjustments. ASC Topic 820 establishes a fair value hierarchy that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The three levels of the fair value hierarchy under ASC Topic 820 are described below: Level 1. Level 1 of the fair value hierarchy consists of assets or liabilities that are valued using observable inputs based upon unadjusted quoted prices in active markets for identical assets or liabilities at the reporting date. Included in this category are cash equivalents and Rabbi trust investments in money market funds which are recorded on the balance sheets at fair value on a recurring basis. Level 2. Level 2 of the fair value hierarchy consists of assets or liabilities that are valued using directly or indirectly observable inputs either corroborated with market data or based on exchange traded market data. Level 2 includes fair values based on industry-standard valuation techniques that consider various assumptions: (i) quoted forward prices, including the use of mid-market pricing within a bid/ask spread; (ii) discount rates; (iii) implied volatility and (iv) other economic factors. Substantially all of these assumptions are observable throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the relevant market. Level 2 financial assets and liabilities included energy-related physical and financial derivative transactions such as forward, option and other contracts for deliveries at active market locations. Level 3. Level 3 of the fair value hierarchy consists of assets or liabilities that are valued using significant unobservable inputs at the reporting date. These unobservable assumptions reflect our assumptions about estimates that market participants would use in pricing the asset or liability, including natural gas basis prices and annualized volatilities of natural gas prices. A significant change to any one of these inputs in isolation could result in a significant upward or downward fluctuation in the fair value measurement. These inputs may be used with industry standard valuation methodologies that result in our best estimate of fair value for the assets or liabilities at the reporting date. Level 3 derivative assets and liabilities included: (i) physical contracts valued at illiquid market locations with no observable market data; (ii) long-dated positions where observable pricing is not available over the majority of the life of the contract; (iii) contracts valued using historical spot price volatility assumptions and (iv) valuations using indicative broker quotes for inactive market locations. Our level 2 and level 3 derivatives are recorded on the balance sheets at fair value on a recurring basis. Other financial instruments including commercial paper, unsecured notes, and other long-term receivables are recorded on the balance sheets at amortized cost. The fair value of the long-term receivable from one of our trading partners related to the Antero contract approximates its carrying value using Level 2 input to estimate the credit loss associated with the receivable. The carrying cost of our commercial paper approximates fair value using Level 2 inputs. The fair value of Washington Gas unsecured notes was estimated based on valuation techniques using indirectly observable inputs corroborated with market data and therefore is classified as Level 2. Summary of Carrying Amounts and Fair value of Financial Instruments The following table summarizes the carrying amounts and fair value of financial assets and liabilities. A financial instrument’s classification within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy. Fair Value Under the Fair Value Hierarchy (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At March 31, 2021 Financial assets Fair value through net income Cash equivalents (a) $ 0.2 $ 0.2 $ — $ — $ 0.2 Rabbi trust investments (b) 15.9 15.9 — — 15.9 Derivative asset - current 4.3 — 0.4 3.9 4.3 Derivative asset - deferred 6.6 — 1.2 5.4 6.6 Fair value through regulatory assets/liabilities Derivative asset - current 6.3 — 0.6 5.7 6.3 Derivative asset - deferred 8.2 — 1.9 6.3 8.2 Total Assets $ 41.5 $ 16.1 $ 4.1 $ 21.3 $ 41.5 Financial Liabilities Fair value through net income Derivative liabilities - current $ (2.6) $ — $ (0.5) $ (2.1) $ (2.6) Derivative liabilities - deferred (24.0) — — (24.0) (24.0) Fair value through regulatory assets/liabilities Derivative liabilities - current (9.0) — (0.6) (8.4) (9.0) Derivative liabilities - deferred (63.6) — — (63.6) (63.6) Amortized cost Commercial paper (d) (72.5) — (72.5) — (72.5) Unsecured notes (e) (1,446.8) — (1,613.5) — (1,613.5) Total Liabilities $ (1,618.5) $ — $ (1,687.1) $ (98.1) $ (1,785.2) (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At December 31, 2020 Financial assets Fair value through net income Cash equivalents (a) $ 3.2 $ 3.2 $ — $ — $ 3.2 Rabbi trust investments (b) 22.0 22.0 — — 22.0 Derivative asset - current 2.1 — 0.7 1.4 2.1 Derivative asset - deferred 4.5 — — 4.5 4.5 Fair value through regulatory assets/liabilities Derivative asset - current 2.9 — 0.9 2.0 2.9 Derivative asset - deferred 6.8 — — 6.8 6.8 Amortized cost Other long-term receivables (c) 1.4 — 1.4 — 1.4 Total Assets $ 42.9 $ 25.2 $ 3.0 $ 14.7 $ 42.9 Financial Liabilities Fair value through net income Derivative liabilities - current $ (0.4) $ — $ — $ (0.4) (0.4) Derivative liabilities - deferred (26.8) — — (26.8) (26.8) Fair value through regulatory assets/liabilities Derivative liabilities - current (6.7) — (0.3) (6.4) (6.7) Derivative liabilities - deferred (61.8) — (0.7) (61.1) (61.8) Amortized cost Commercial paper (d) (285.0) — (285.0) — (285.0) Unsecured notes (e) (1,446.9) — (1,779.8) — (1,779.8) Total Liabilities $ (1,827.6) $ — $ (2,065.8) $ (94.7) $ (2,160.5) (a) Cash equivalents represent the amounts invested in money market funds and were included in "Cash and cash equivalents" of the accompanying balance sheets. (b) Rabbi Trust investments are invested in money market funds. At March 31, 2021, carrying amount of $2.1 million and $13.8 million was included in "Current assets — Other" and "Deferred charges and other assets — Other" of the accompanying balance sheets, respectively; At December 31, 2020, carrying amount of $6.7 million and $15.3 million was included in "Current assets — Other" and "Deferred charges and other assets — Other", respectively. (c) Amount represents a long-term receivable from one of our trading partners related to the Antero contract at December 31, 2020. The receivable became current and netted against the payable to the trading partner in "Account payable and other accrued liabilities" on the accompanying balance sheets at March 31, 2021. (d) The balance at March 31, 2021 included $72.5 million located in “Long-term debt” on the accompanying balance sheets. The balance at December 31, 2020 included $185.0 million located in "Notes payable", and $100.0 million located in “Long-term debt” on the accompanying balance sheets. (e) Includes adjustments for current maturities and unamortized discounts, as applicable. The amount was included in "Long-term debt" on the accompanying balance sheets. Quantitative Information About Unobservable Inputs The following table includes quantitative information about the significant unobservable inputs used in the fair value measurement of our Level 3 financial instruments and the respective fair values of the net derivative asset and liability positions. Quantitative Information about Level 3 Fair Value Measurements (In millions) Net Fair Value Valuation Techniques Unobservable Inputs Weighted Average Range March 31, 2021 $(76.80) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) $(0.41) $(1.168)-$1.963 December 31, 2020 $(80.00) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) $(0.36) $(0.910)-$2.073 Reconciliation of Level 3 Assets and Liabilities The following table presents a reconciliation of changes in net fair value of Level 3 derivative instruments measured at fair value on a recurring basis. Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs Three Months Ended March 31, (In millions) 2021 2020 Balance at beginning of period $ (80.0) $ (84.8) Realized and unrealized gains (losses) Recorded to income 2.4 3.1 Recorded to regulatory assets — Gas costs (5.4) 9.1 Settlements 6.2 1.4 Balance at end of period $ (76.8) $ (71.2) Transfers between different levels of the fair value hierarchy may occur based on fluctuations in the valuation inputs and on the level of observable inputs used to value the instruments from period to period. Transfers out of Level 3 were due to valuations that experienced an increase in observable market inputs. Transfers into Level 3 were due to an increase in unobservable market inputs, primarily pricing points. All amounts recorded to income are from the utility cost of gas. The following table presents the unrealized gains (losses) attributable to Level 3 derivative instruments measured at fair value on a recurring basis. Unrealized Gains (Losses) Recorded for Level 3 Measurements Three Months Ended March 31, (In millions) 2021 2020 Recorded to income — Utility cost of gas $ 1.6 $ 2.3 Recorded to regulatory assets — Gas costs (6.3) 7.6 Total $ (4.7) $ 9.9

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS Corporate Service Allocation As a subsidiary of AltaGas, Washington Gas is charged a proportionate share of corporate governance and other shared services costs from AltaGas, primarily related to human resources, employee benefits, finance, legal, accounting, tax, information technology services, and office services. AltaGas charges Washington Gas for the total shared service costs at the lower of cost or market, and Washington Gas in turn allocates a portion of the costs to WGL’s other subsidiaries at the higher of cost or market. Washington Gas records a payable for the total shared service costs allocated to all of WGL's subsidiaries in "Payable to associated companies" and a receivable for the shared service costs allocated to WGL’s other subsidiaries excluding Washington Gas in “Receivables from associated companies” on its balance sheets. Additionally, Washington Gas received certain corporate services from SEMCO Energy, Inc., (SEMCO), a subsidiary of AltaGas. Washington Gas records in "Payable to associated companies" on its balance sheets for the services provided by SEMCO. The expenses associated with services provided by AltaGas and SEMCO are recorded to “Operation and maintenance” on Washington Gas' statements of operations. The net expenses of $5.0 million and $5.0 million were included in “Operation and maintenance” on the statements of operations for the three months ended March 31, 2021 and 2020, respectively, reflecting the corporate service cost allocated to Washington Gas. In addition, Washington Gas provides accounting, treasury, legal and other administrative and general support to WGL’s subsidiaries and various AltaGas U.S. entities, and files consolidated tax returns that include affiliated taxable transactions. Washington Gas bills affiliates to which it provides services in accordance with regulatory requirements for the actual cost of providing these services, which approximates their market value. To the extent such billings are outstanding, they are reflected in “Receivables from associated companies” on Washington Gas’ balance sheets. Washington Gas assigns or allocates these costs directly to its affiliates and, therefore, does not recognize revenues or expenses associated with providing these services. Washington Gas believes that allocations based on broad measures of business activity are appropriate for allocating expenses resulting from common services. Affiliate entities are allocated a portion of common services based on a formula driven by appropriate indicators of activity, as approved by management. Project Financing WGL Energy Systems, Inc. (WGL Energy Systems), an indirect, wholly owned subsidiary of WGL, obtains third-party project financing for energy management services projects with the federal government under Washington Gas’s area-wide contract. As work is performed, Washington Gas establishes a contract asset in “Receivables” representing the government’s obligation to remit principal and interest and records a “Payable to associated company” to WGL Energy Systems for the construction work performed for the same amount. At March 31, 2021, Washington Gas recorded $6.7 million of contract assets in “Receivables” and a $6.7 million payable to WGL Energy Systems in “Payables to associated companies,” respectively, for energy management services projects financed by WGL Energy Systems that were not complete. At December 31, 2020, Washington Gas recorded $16.1 million of contract assets in “Receivables” and a $16.1 million payable to WGL Energy Systems in “Payables to associated companies,” respectively, for energy management services projects financed by WGL Energy Systems that were not complete. Related Party Transactions with Hampshire Hampshire Gas Company (Hampshire), a wholly owned subsidiary of WGL, owns full and partial interests in underground natural gas storage facilities, including pipeline delivery facilities located in and around Hampshire County, West Virginia, and operates those facilities to serve Washington Gas, which purchases all of the storage services of Hampshire. Washington Gas includes the cost of these services in the bills sent to its customers and records the cost of the services in "Operation and maintenance" in its statements of operations. Hampshire operates under a “pass-through” cost of service-based tariff approved by the FERC and adjusts its billing rates to Washington Gas on a periodic basis to account for changes in its investment in utility plant and associated expenses. The arrangement between Hampshire and Washington Gas is classified as an operating lease. A right-of-use (ROU) asset and lease liability was not recognized upon the adoption of ASC 842 because all the costs associated with the arrangement are variable. Washington Gas recorded expenses related to the cost of services provided by Hampshire in "Operation and maintenance " on Washington Gas' statements of operations of $2.1 million and $2.0 million for three months ended March 31, 2021, and 2020, respectively. The outstanding balance not cleared between Washington Gas and Hampshire at the end of the reporting period was recorded in "Payable to associated companies" of Washington Gas' balance sheets. Related Party Income Taxes Washington Gas is included in the AltaGas Services (US) Inc.(ASUS) consolidated income tax returns. We have a tax sharing policy with ASUS, an indirect, wholly owned subsidiary of AltaGas, that allocates consolidated tax liabilities and benefits using a ratio determined by the separate taxable income for each member applied to the consolidated return tax liability of the group. State income tax returns are filed on a separate company basis in most states and on a unitary basis as required, where we or the consolidated ASUS group have operations and/or a requirement to file. At March 31, 2021 Washington Gas recorded a $0.6 million receivable in "Receivables from associated companies" and a $0.6 million payable in "Payables to associated companies" under the ASUS tax sharing policy on Washington Gas' balance sheets, respectively. At December 31, 2020, Washington Gas recorded a $112.2 million receivable in "Receivables from associated companies" and a $0.6 million payable in "Payables to associated companies" under the ASUS tax sharing policy on Washington Gas' balance sheets, respectively. Other Related Party Transactions In connection with billing for unregulated third-party marketers, including WGL Energy Services and with other miscellaneous billing processes, Washington Gas collects cash on behalf of affiliates and transfers the cash in a reasonable time period. Cash collected by Washington Gas on behalf of its affiliates but not yet transferred is recorded in “Payables to associated companies” on Washington Gas’ balance sheets. Washington Gas provides gas balancing services related to storage, injections, withdrawals and deliveries to all energy marketers participating in the sale of natural gas on an unregulated basis through the customer choice programs that operate in its service territory. These balancing services include the sale of natural gas supply commodities related to various peaking arrangements contractually supplied to Washington Gas and then partially allocated and assigned by Washington Gas to the energy marketers, including WGL Energy Services. Washington Gas records revenues in "Operating revenue" of its statements of operations for these balancing services pursuant to tariffs approved by the appropriate regulatory bodies. The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Gas Balancing Service Charges (In millions) Three Months Ended March 31, 2021 2020 Gas balancing service charge $ 7.7 $ 6.6 As a result of these balancing services, an imbalance is created for volumes of natural gas received by Washington Gas that are not equal to the volumes of natural gas delivered to customers of the energy marketers. Washington Gas recorded $1.4 million and $2.0 million receivable from WGL Energy Services at March 31, 2021 and December 31, 2020, respectively, related to an imbalance in gas volumes. The receivables were recorded in "Receivables" on Washington Gas' balance sheets.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income	ACCUMULATED OTHER COMPREHENSIVE INCOME The following table shows the changes in accumulated other comprehensive income (AOCI) by component for the reporting periods. Changes in Accumulated Other Comprehensive Income by Component Three Months Ended March 31, (In thousands) 2021 2020 Beginning Balance $ 1,577 $ 4,576 Amortization of prior service credit (a)(b) (81) (304) Amortization of actuarial loss (a)(b)(c) 34 781 Actuarial gain arising during the period (a) 1,436 1,910 Current-period other comprehensive income 1,389 2,387 Income tax expense related to pension and other post-retirement benefit plans retained in AOCI (c) 367 620 Ending Balance $ 2,599 $ 6,343 (a) The accumulated other comprehensive income components are included in the computation of net periodic benefit cost. (b) Amortization of prior service cost and amortization of actuarial loss represent the amounts reclassified out of AOCI to “Other income (expense)-net” of statements of operations for the reporting periods. (c) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the MRVA used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. Refer to Note 1 — Accounting Policies for further discussion.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2021
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION The following table details the changes in operating assets and liabilities from operating activities, cash payments that have been included in the determination of earnings and non-cash investing and financing activities. (In thousands) Three Months Ended March 31, 2021 2020 CHANGES IN OPERATING ASSETS AND LIABILITIES Receivables $ (14,583) $ 53,278 (Receivables from) Payables to associated companies — net 127,218 11,649 Gas costs and other regulatory assets/liabilities — net (5,648) (43,613) Storage gas 41,611 56,430 Prepaid taxes 5,712 3,711 Accounts payable and other accrued liabilities (36,860) (59,144) Customer deposits and advance payments (13,185) (6,949) Accrued taxes 31 5,499 Other current assets 5,756 10,273 Other current liabilities (365) (243) Deferred gas costs — net 33,063 24,874 Deferred assets — other 2,019 (1,014) Deferred liabilities — other (2,427) (1,463) Pension and other post-retirement benefits (5,613) (4,245) Changes in operating assets and liabilities $ 136,729 $ 49,043 SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION Income taxes paid (refunded) — net $ — $ (3,880) Interest paid including interest for finance leases $ 31,437 $ 30,965 Cash paid for amounts included in the measurement of operating lease liabilities $ 1,535 $ 1,490 SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES: Right-of-use assets obtained in exchange for new operating lease liabilities $ 1,788 $ — Right-of-use assets obtained in exchange for new finance lease liabilities $ 425 $ — Capital expenditure accruals included in accounts payable and other accrued liabilities $ 44,996 $ 45,817 The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within Washington Gas’ balance sheets that sums to the total of such amounts shown on the statements of cash flows. (In thousands) March 31, 2021 March 31, 2020 Cash and cash equivalents $ 11,056 $ 42,418 Restricted cash included in Current assets-Other 2,083 11,332 Restricted cash included in Deferred charges and other assets-Other 13,826 28,113 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 26,965 $ 81,863 Restricted cash included in "Current assets — Other" and "Deferred charges and other assets — Other" on the balance sheets represents amount of investment in rabbi trusts to fund deferred compensation, pension and other post-retirement benefits for certain management personnel and directors. The funds in the rabbi trusts can only be used to pay for plan participant benefits and other plan expenses such as investment fees or trustee fees. The funds are invested in money market funds at the end of March 31, 2021 and 2020. Refer to Note 8 — Pension and Other Post-Retirement Benefit Plans for further discussion of rabbi trusts.

Accounting Policies (Policies)

Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Washington Gas is an indirect, wholly owned subsidiary of, among other entities, AltaGas and WGL. Wrangler SPE LLC (Wrangler), a bankruptcy remote, special purpose entity, directly owns the common stock of Washington Gas. Wrangler was formed for the purpose of “ring fencing” Washington Gas, that is removing Washington Gas from the bankruptcy estate of AltaGas and its affiliates in the event that any parent or affiliate entity becomes the subject of bankruptcy or insolvency proceedings. Wrangler is the wholly owned subsidiary of WGL and AltaGas. The condensed financial statements of Washington Gas have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Therefore, certain financial information and note disclosures accompanying annual financial statements prepared in accordance with generally accepted accounting principles in the United States of America (GAAP) are omitted in this interim report. The interim condensed financial statements and accompanying notes should be read in conjunction with the Financial Statements on Form 10-K for the year ended December 31, 2020. Due to the seasonal nature of our business, the results of operations for the periods presented in this report are not necessarily indicative of actual results for the full years ending December 31, 2021 and 2020.
New Accounting Pronouncements	The following table represents accounting standards adopted by Washington Gas during the three months ended March 31, 2021. ACCOUNTING STANDARDS ADOPTED IN CALENDAR YEAR 2021 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2019-12, Income Taxes (Topic 740) Simplifying the Accounting for Income Taxes As part of FASB's Simplification Initiative, this standard amends ASC Topic 740 by removing certain exceptions to the general principles and clarifying and amending other current guidance. Early adoption is permitted. January 1, 2021 The adoption of this standard did not have a material effect on our financial statements. ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting, including other subsequent ASUs further amending and clarifying the guidance. This standard provides optional expedients and exceptions to ease the potential accounting burden associated with transitioning away from reference rates that are expected to be discontinued. The amendments may be elected prospectively to contract modifications and hedging relationships existing on or after the date of adoption and through December 31, 2022. January 1, 2021 Currently, our credit facilities and carrying charges in certain commodity sale arrangements, reference LIBOR. The discontinuation of LIBOR will require these arrangements to be modified to an alternative interest rate. The majority of our credit facilities include fallback provisions that contemplate the replacement of LIBOR. The Company has made a policy election to adopt the optional expedients related to contract modifications related to its debt and certain other arrangements and will apply the relief on a prospective basis as modifications are made. The Company continues to monitor the activities of regulators and financial institutions to transition to an alternative reference rate, and also continues to review additional arrangements for references to LIBOR. Accordingly, the Company may make additional optional elections in the future. ASU 2020-10, Codification Improvements The amendments in this ASU provide clarification and improve the codification in recently issued accounting standards. January 1, 2021 The adoption of this standard did not have a material effect on our financial statements.
Revenue from Contract with Customers	Washington Gas sells natural gas and distribution services to residential, commercial, industrial and governmental customers through regulated tariff rates approved by regulatory commissions in the jurisdictions where it operates. Customers are billed monthly based on regular meter readings. Customer billings are based on two main components: (i) a fixed service fee and (ii) a variable fee based on usage. For customers who choose to purchase their natural gas from Washington Gas, the bill will include a usage based charge for the cost of the commodity. Revenue is recognized over time as natural gas is delivered or as service is performed. Since meter readings are performed on a cycle basis, Washington Gas recognizes accrued revenue for any services rendered to its customers but not billed at month-end. The tariff sales are generally considered daily or “at-will” contracts as customers may cancel their service at any time (subject to notification requirements in the tariff), and revenue generally represents the amount Washington Gas is entitled to invoice. There are certain contracts that have terms of one year or longer. For these contracts, revenue is recognized based on the amount Washington Gas is entitled to bill the customer. Customers have the choice to purchase natural gas from competitive service providers. Washington Gas charges the competitive service providers balancing fees to manage the natural gas transportation imbalances. Where regulations require, Washington Gas issues customers a consolidated bill to include the natural gas supplied by the competitive service providers and distribution of natural gas. Washington Gas recognizes revenue only for distribution services that it has provided to the customer, and the balancing fees for the services provided to the competitive service provider.
Short-Term Debt	Washington Gas satisfies the short-term financing requirements through the sale of commercial paper, or through bank borrowings. Due to the seasonal nature of our operations, short-term financing requirements can vary significantly during the year. Revolving credit agreements are maintained to support outstanding commercial paper and to permit short-term borrowing flexibility. The policy of Washington Gas is to maintain bank credit facilities in amounts equal to or greater than the expected maximum commercial paper position.
Derivatives	Washington Gas enters into contracts that qualify as derivative instruments and are accounted for under ASC Topic 815. These derivative instruments are recorded at fair value on our balance sheets and Washington Gas does not currently designate any derivatives as hedges under ASC Topic 815. Washington Gas’ derivative instruments relate to: (i) Washington Gas’ asset optimization program; (ii) managing price risk associated with the purchase of gas to serve utility customers and (iii) managing interest rate risk. Asset Optimization. Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources during periods when these resources are not being used to physically serve utility customers. Specifically, Washington Gas utilizes its transportation capacity assets to benefit from favorable natural gas prices between different geographic locations and utilizes its storage capacity assets to benefit from favorable natural gas prices between different time periods. As part of this asset optimization program, Washington Gas enters into physical and financial derivative transactions in the form of forward, futures and option contracts with the primary objective of securing operating margins that Washington Gas will ultimately realize. The derivative transactions entered into under this program are subject to mark-to-market accounting treatment under ASC Topic 820. Regulatory sharing mechanisms provide for the annual realized profit from these transactions to be shared between Washington Gas’ shareholder and customers; therefore, changes in fair value are recorded through earnings, or as regulatory assets or liabilities to the extent that it is probable that realized gains and losses associated with these derivative transactions will be included in the rates charged to customers when they are realized. Unrealized gains and losses recorded to earnings may cause significant period-to-period volatility; this volatility does not change the operating margins that Washington Gas expects to ultimately realize from these transactions through the use of its storage and transportation capacity resources. Washington Gas has a collaborative arrangement with a third party to facilitate the asset optimization program. The collaborative arrangement allocates a tiered percentage of profits or losses to the third party as compensation for its participation. The costs recorded by Washington Gas related to the collaborative arrangement totaled $1.3 million and $1.0 million for the three months ended March 31, 2021 and 2020, respectively. These amounts were recorded in “Utility cost of gas” on Washington Gas’ statements of operations. Either party may terminate the collaborative arrangement through the delivery of a termination notice. In such an event, Washington Gas may make a payment upon termination. The following table presents the net margin recorded to “Utility cost of gas” after sharing and management fees associated with our asset optimization transactions. Net Margins for Asset Optimization (In millions) Three Months Ended March 31, 2021 2020 Realized gain $ 2.9 $ 2.3 Unrealized gain 5.3 6.1 Net margin gain $ 8.2 $ 8.4
Managing Price Risk	Managing Price Risk. To manage price risk associated with acquiring natural gas supply for utility customers, Washington Gas enters into physical and financial derivative transactions in the form of forward, option and other contracts, as authorized by its regulators. Any gains and losses associated with these derivatives are recorded as regulatory liabilities or assets, respectively, to reflect the rate treatment for these economic hedging activities.
Derivatives, Offsetting	We are exposed to credit risk from derivative instruments with wholesale counterparties, which is represented by the fair value of these instruments at the reporting date. We actively monitor and work to minimize counterparty concentration risk through various practices.
Fair Value Measurements	We measure the fair value of our financial assets and liabilities using a combination of the income and market approaches in accordance with ASC Topic 820. These financial assets and liabilities primarily consist of derivatives recorded on our balance sheets under ASC Topic 815 and short-term investments, other long-term receivable, commercial paper and long-term debt outstanding required to be disclosed at fair value. Under ASC Topic 820, fair value is defined as the exit price, representing the amount that would be received in the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. To value our financial instruments, we use market data or assumptions that market participants would use, including assumptions about credit risk (both our own credit risk and the counterparty’s credit risk) and the risks inherent in the inputs to valuation. We enter into derivative contracts in the futures and over-the-counter (OTC) wholesale and retail markets. These markets are the principal markets for the respective wholesale and retail contracts. Our relevant market participants are our existing counterparties and others who have participated in energy transactions at our delivery points. These participants have access to the same market data as Washington Gas. Valuations are generally based on pricing service data or indicative broker quotes depending on the market location. We measure the net credit exposure at the counterparty level where the right to set-off exists. The net exposure is determined using the mark-to-market exposure adjusted for collateral, letters of credit and parent guarantees. We use published default rates from Standard & Poor’s Ratings Services and Moody’s Investors Service as inputs for determining credit adjustments. ASC Topic 820 establishes a fair value hierarchy that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The three levels of the fair value hierarchy under ASC Topic 820 are described below: Level 1. Level 1 of the fair value hierarchy consists of assets or liabilities that are valued using observable inputs based upon unadjusted quoted prices in active markets for identical assets or liabilities at the reporting date. Included in this category are cash equivalents and Rabbi trust investments in money market funds which are recorded on the balance sheets at fair value on a recurring basis. Level 2. Level 2 of the fair value hierarchy consists of assets or liabilities that are valued using directly or indirectly observable inputs either corroborated with market data or based on exchange traded market data. Level 2 includes fair values based on industry-standard valuation techniques that consider various assumptions: (i) quoted forward prices, including the use of mid-market pricing within a bid/ask spread; (ii) discount rates; (iii) implied volatility and (iv) other economic factors. Substantially all of these assumptions are observable throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the relevant market. Level 2 financial assets and liabilities included energy-related physical and financial derivative transactions such as forward, option and other contracts for deliveries at active market locations. Level 3. Level 3 of the fair value hierarchy consists of assets or liabilities that are valued using significant unobservable inputs at the reporting date. These unobservable assumptions reflect our assumptions about estimates that market participants would use in pricing the asset or liability, including natural gas basis prices and annualized volatilities of natural gas prices. A significant change to any one of these inputs in isolation could result in a significant upward or downward fluctuation in the fair value measurement. These inputs may be used with industry standard valuation methodologies that result in our best estimate of fair value for the assets or liabilities at the reporting date. Level 3 derivative assets and liabilities included: (i) physical contracts valued at illiquid market locations with no observable market data; (ii) long-dated positions where observable pricing is not available over the majority of the life of the contract; (iii) contracts valued using historical spot price volatility assumptions and (iv) valuations using indicative broker quotes for inactive market locations. Our level 2 and level 3 derivatives are recorded on the balance sheets at fair value on a recurring basis. Other financial instruments including commercial paper, unsecured notes, and other long-term receivables are recorded on the balance sheets at amortized cost. The fair value of the long-term receivable from one of our trading partners related to the Antero contract approximates its carrying value using Level 2 input to estimate the credit loss associated with the receivable. The carrying cost of our commercial paper approximates fair value using Level 2 inputs. The fair value of Washington Gas unsecured notes was estimated based on valuation techniques using indirectly observable inputs corroborated with market data and therefore is classified as Level 2.

Accounting Policies (Tables)

Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Accounting standards adopted in the current fiscal year	The following tables summarize the effect of the change in accounting principle on the primary financial statement line items on our condensed statements of operations, condensed statements of comprehensive income, and condensed statements of cash flows. The following Notes have been impacted by the change: Note 7 — Components of Total Equity , Note 8 — Pension and Other Post — Retirement Benefit Plans, and Note 13 — Accumulated Other Comprehensive Income . Three Months Ended March 31, 2020 (In thousands) As Previously Reported Adjustment As Adjusted Condensed Statements of Operations Other income (expense) — net $ 3,070 $ 2,262 $ 5,332 Income tax expense $ 31,459 $ 587 $ 32,046 Net income $ 126,084 $ 1,675 $ 127,759 Condensed Statements of Comprehensive Income Other comprehensive income $ 1,941 $ (174) $ 1,767 Comprehensive income $ 128,025 $ 1,501 $ 129,526 Condensed Statements of Cash Flows Net income $ 126,084 $ 1,675 $ 127,759 ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES Accrued/deferred pension and other post-retirement benefit cost (benefit) $ 465 $ (2,262) $ (1,797) Deferred income taxes — net $ 31,609 $ 587 $ 32,196 The following table represents accounting standards adopted by Washington Gas during the three months ended March 31, 2021. ACCOUNTING STANDARDS ADOPTED IN CALENDAR YEAR 2021 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2019-12, Income Taxes (Topic 740) Simplifying the Accounting for Income Taxes As part of FASB's Simplification Initiative, this standard amends ASC Topic 740 by removing certain exceptions to the general principles and clarifying and amending other current guidance. Early adoption is permitted. January 1, 2021 The adoption of this standard did not have a material effect on our financial statements. ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting, including other subsequent ASUs further amending and clarifying the guidance. This standard provides optional expedients and exceptions to ease the potential accounting burden associated with transitioning away from reference rates that are expected to be discontinued. The amendments may be elected prospectively to contract modifications and hedging relationships existing on or after the date of adoption and through December 31, 2022. January 1, 2021 Currently, our credit facilities and carrying charges in certain commodity sale arrangements, reference LIBOR. The discontinuation of LIBOR will require these arrangements to be modified to an alternative interest rate. The majority of our credit facilities include fallback provisions that contemplate the replacement of LIBOR. The Company has made a policy election to adopt the optional expedients related to contract modifications related to its debt and certain other arrangements and will apply the relief on a prospective basis as modifications are made. The Company continues to monitor the activities of regulators and financial institutions to transition to an alternative reference rate, and also continues to review additional arrangements for references to LIBOR. Accordingly, the Company may make additional optional elections in the future. ASU 2020-10, Codification Improvements The amendments in this ASU provide clarification and improve the codification in recently issued accounting standards. January 1, 2021 The adoption of this standard did not have a material effect on our financial statements.

Credit Losses (Tables)

Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2021
Credit Loss [Abstract]
Asset Optimization, Allowance for Credit Loss	The following table presents the activity of allowance for doubtful accounts by types for the reporting periods. Three Months Ended Three Months Ended (In millions) Account Receivables and Unbilled Revenue Asset Optimization Account Receivables and Unbilled Revenue Asset Optimization Balance, beginning of period $ 27.3 $ 0.1 $ 18.7 $ — Provision 7.5 (0.1) 5.9 — Write offs (2.8) — (7.5) — Recoveries 0.4 — 0.3 — Adjustment upon adoption of ASC 326 — — 1.4 0.1 Balance, end of period $ 32.4 $ — $ 18.8 $ 0.1
Account Receivables and Unbilled Revenue, Allowance for Credit Loss	The following table presents the activity of allowance for doubtful accounts by types for the reporting periods. Three Months Ended Three Months Ended (In millions) Account Receivables and Unbilled Revenue Asset Optimization Account Receivables and Unbilled Revenue Asset Optimization Balance, beginning of period $ 27.3 $ 0.1 $ 18.7 $ — Provision 7.5 (0.1) 5.9 — Write offs (2.8) — (7.5) — Recoveries 0.4 — 0.3 — Adjustment upon adoption of ASC 326 — — 1.4 0.1 Balance, end of period $ 32.4 $ — $ 18.8 $ 0.1

Revenue from Contracts With C_2

Revenue from Contracts With Customers (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table disaggregates revenue by type of service for the periods. Disaggregated Revenue by Type of Service Three Months Ended March 31, (In millions) 2021 2020 Revenue from contracts with customers Gas and transportation sales Gas sold and delivered $ 442.6 $ 346.3 Gas delivered for others 102.9 97.6 Other 12.8 13.7 Other revenues 0.9 0.7 Total revenue from contracts with customers $ 559.2 $ 458.3 Other sources of revenue Revenue from alternative revenue programs (a) $ 21.6 $ 40.6 Other (b) 1.7 2.8 Total revenue from other sources $ 23.3 $ 43.4 Total Operating Revenue $ 582.5 $ 501.7 (a) Washington Gas has determined that its Revenue Normalization Adjustment (RNA), Weather Normalization Adjustment (WNA), and Conservation and Ratemaking Efficiency (CARE) Ratemaking Adjustment (CRA) billing adjustment mechanisms and accelerated pipe replacement programs are alternative revenue programs and accounted for under ASC Topic 980. (b) The amount includes late fees billed. The decreases from prior periods were primarily caused by not billing of late payment fees due to COVID-19 as required by regulatory orders.
Contract Assets from Contracts with Customers	The following table shows the beginning and ending balances of contract assets from contracts with customers for the reporting periods, which were included within "Receivables" on Washington Gas' condensed balance sheets. (In millions) 2021 2020 Contract assets at January 1 $ 16.1 $ 44.2 Contract assets at March 31 $ 6.7 $ 46.1 Increase (decrease) in contract assets (a) $ (9.4) $ 1.9 ( a) Decrease in 2021 reflected projects accepted by federal government offset to the contract asset was a reduction to "Payable to associated companies".

Accounts Payable and Other Ac_2

Accounts Payable and Other Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable and Other Accrued Liabilities	The table below provides details for the amounts included in “Accounts payable and other accrued liabilities” on the balance sheets. (In millions) March 31, 2021 December 31, 2020 Accounts payable—trade $ 168.7 $ 201.2 Employee benefits and payroll accruals 10.2 22.3 Wages payable 20.8 19.5 Accrued interest 3.4 18.4 Other accrued liabilities (a) 20.1 31.1 Total $ 223.2 $ 292.5 (a) Amount at December 31, 2020 included $12.5 million liability associated with the Antero judgment which was paid in February 2021.

Short-Term Debt (Tables)

Short-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Short-term Debt [Abstract]
Committed Credit Available	The following is a summary of committed credit available at March 31, 2021 and December 31, 2020. Committed Credit Available (In millions) March 31, 2021 December 31, 2020 Committed credit agreements Unsecured revolving credit facility, expires July 19, 2024 (a) $450.0 $450.0 Less: Commercial Paper outstanding (b) (72.5) (285.0) Net committed credit available $377.5 $165.0 Weighted average interest rate 0.23% 0.31% (a) Washington Gas has the right to request extensions with the bank group 's approval. Washington Gas’ revolving credit facility permits it to borrow an additional $100.0 million, with the bank groups' approval, for a total potential maximum borrowing of $550.0 million. (b) The amount represents principal amount of commercial paper.

Long Term Debt (Tables)

Long Term Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table shows the long-term debt outstanding at March 31, 2021 and December 31, 2020. Long Term Debt Outstanding (In millions) March 31, 2021 December 31, 2020 Washington Gas Unsecured Notes (a) $ 1,446.0 $ 1,446.0 Commercial Paper 72.5 100.0 Total Principal Amounts of Long-Term Debt $ 1,518.5 $ 1,546.0 Unamortized premium (discount) 12.3 12.5 Unamortized debt expense (11.5) (11.6) Non-current finance lease liability 0.7 0.3 Total Carrying Amount of Long-Term Debt $ 1,520.0 $ 1,547.2 Weighted average interest rate (b) 4.46 % 4.46 % (a) Includes MTNs and private placement notes. The amount represents face value of Washington Gas' unsecured notes. (b) Weighted average interest rate is for the Washington Gas unsecured notes.

Components of Total Equity (Tab

Components of Total Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Schedule of Stockholders Equity	Common Stock Paid-In Capital Retained Earnings (b) Accumulated Other Comprehensive Income, Net of Taxes (b) (In thousands, except shares) Shares Amount Total (b) Three Months Ended March 31, 2021 Balance at December 31, 2020 46,479,536 $ 46,479 $ 1,204,273 $ 603,596 $ 1,577 $ 1,855,925 Net income — — — 133,614 — 133,614 Other comprehensive income — — — — 1,022 1,022 Capital contribution from parent — — — — — — Common stock dividends declared — — — (25,000) — (25,000) Balance at March 31, 2021 46,479,536 $ 46,479 $ 1,204,273 $ 712,210 $ 2,599 $ 1,965,561 Three Months Ended March 31, 2020 Balance at December 31, 2019 46,479,536 $ 46,479 $ 979,273 $ 548,264 $ 4,576 $ 1,578,592 Net income — — — 127,759 — 127,759 Other comprehensive income — — — — 1,767 1,767 Capital contribution from parent — — 125,000 — — 125,000 ASU 2016-13 implementation (a) — — — (1,543) — (1,543) Common stock dividends declared — — — (25,000) — (25,000) Balance at March 31, 2020 46,479,536 $ 46,479 $ 1,104,273 $ 649,480 $ 6,343 $ 1,806,575 (a) Due to implementation of ASU 2016-13 Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, see Note 2 — Credit Losses for further information. (b) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the MRVA used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. Refer to Note 1 — Accounting Policies for further discussion.

Pension and Other Post-Retire_2

Pension and Other Post-Retirement Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Costs (Income)	The following table shows the components of the net periodic benefit costs (income) recognized in our financial statements. Components of Net Periodic Benefit Costs (Income) (b) Three Months Ended March 31, 2021 2020 (a) (In millions) Pension Benefits Health and Life Benefits Pension Health and Life Benefits Service cost $ 3.1 $ 1.6 $ 3.2 $ 1.3 Interest cost 7.6 2.0 8.9 2.3 Expected return on plan assets (10.7) (5.7) (10.8) (5.9) Recognized prior service cost (credit) 0.1 (3.4) 0.1 (3.4) Recognized actuarial loss (gain) 0.3 (1.2) 2.4 (0.5) Settlement charge 1.0 — 1.1 — Net periodic benefit cost (income) 1.4 (6.7) 4.9 (6.2) Allocation to affiliates — 0.2 (0.3) 0.4 Adjusted net periodic benefit cost (income) 1.4 (6.5) 4.6 (5.8) Amount allocated to construction projects (0.6) (0.3) (0.4) (0.2) Amount charged (credited) to expense $ 0.8 $ (6.8) $ 4.2 $ (6.0) (a) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the MRVA used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. Refer to Note 1 — Accounting Policies for further discussion. (b) The other components of net benefit cost are presented separately from service cost and recorded in “Other income (expense)-net” on the accompanying statements of operations .

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gains and (Losses) on Derivative Instruments	The following table presents the net margin recorded to “Utility cost of gas” after sharing and management fees associated with our asset optimization transactions. Net Margins for Asset Optimization (In millions) Three Months Ended March 31, 2021 2020 Realized gain $ 2.9 $ 2.3 Unrealized gain 5.3 6.1 Net margin gain $ 8.2 $ 8.4 The following tables present all gains and losses associated with derivative instruments for the three months ended March 31, 2021 and 2020. Gains and (Losses) on Derivative Instruments (In millions) Three Months Ended March 31, 2021 2020 Recorded to income-Utility cost of gas $ 0.7 $ 3.1 Recorded to regulatory assets-Gas costs (8.0) 8.9 Total $ (7.3) $ 12.0
Absolute Notional Amounts of Open Positions on Derivative Instruments	The following table presents notional amounts of our outstanding derivatives at March 31, 2021 and December 31, 2020. Absolute Notional Amounts of Open Positions on Derivative Instruments March 31, 2021 December 31, 2020 Natural Gas (In millions of therms) Asset optimization & trading 10,353.0 10,471.0 Other risk-management activities 794.0 881.0
Balance Sheet Classification of Derivative Instruments	The following table presents the balance sheet line items where derivatives are recognized. Washington Gas has elected to offset the fair value of recognized derivative instruments against the right to reclaim or the obligation to return collateral for derivative instruments executed under the same master netting arrangement in accordance with ASC Topic 815. All recognized derivative contracts and associated financial collateral subject to a master netting arrangement or similar that is eligible for offset under ASC Topic 815 have been presented net in the balance sheets. Balance Sheet Classification of Derivative Instruments (In millions) Gross amounts Gross amounts Netting of Net amounts March 31, 2021 Derivative assets (a) $ 25.8 $ (0.4) $ — $ 25.4 Derivative liabilities (b) (99.6) 0.4 — $ (99.2) Net derivative assets (liabilities) $ (73.8) $ — $ — $ (73.8) December 31, 2020 Derivative assets (a) $ 17.8 $ (1.5) $ — $ 16.3 Derivative liabilities (b) (98.8) 1.5 1.6 (95.7) Net derivative assets (liabilities) $ (81.0) $ — $ 1.6 $ (79.4) (a) Derivative assets at March 31, 2021 include $10.6 million recorded in "Current assets — Derivatives" and $14.8 million in" Deferred charges and other assets — Derivatives" on Washington Gas' balance sheets; Derivative assets at December 31, 2020 include $5.0 million recorded in "Current assets —Derivatives" and $11.3 million in" Deferred charges and other assets — Derivatives" on Washington Gas' condensed balance sheets. (b) Derivative liabilities at March 31, 2021 include $11.6 million recorded in "Current liabilities — Derivatives " and $87.6 million recorded in " Deferred credits — Derivatives" on Washington Gas' balance sheets; Derivative liabilities at December 31, 2020 include $7.1 million recorded in "Current liabilities — Derivatives " and $88.6 million recorded in " Deferred credits — Derivatives" on Washington Gas' condensed balance sheets.
Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features	The following table shows the aggregate fair value of all derivative instruments with credit-related contingent features that are in a liability position, as well as the maximum amount of collateral that would be required if the most intrusive credit-risk-related contingent features underlying these agreements were triggered on March 31, 2021 and December 31, 2020, respectively. Potential Collateral Requirements for Derivative Liabilities (In millions) March 31, 2021 December 31, 2020 Derivative liabilities with credit-risk-contingent features $ 0.1 $ 0.7 Maximum potential collateral requirements $ 0.1 $ 0.6

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements Under the Fair Value Hierarchy	The following table summarizes the carrying amounts and fair value of financial assets and liabilities. A financial instrument’s classification within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy. Fair Value Under the Fair Value Hierarchy (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At March 31, 2021 Financial assets Fair value through net income Cash equivalents (a) $ 0.2 $ 0.2 $ — $ — $ 0.2 Rabbi trust investments (b) 15.9 15.9 — — 15.9 Derivative asset - current 4.3 — 0.4 3.9 4.3 Derivative asset - deferred 6.6 — 1.2 5.4 6.6 Fair value through regulatory assets/liabilities Derivative asset - current 6.3 — 0.6 5.7 6.3 Derivative asset - deferred 8.2 — 1.9 6.3 8.2 Total Assets $ 41.5 $ 16.1 $ 4.1 $ 21.3 $ 41.5 Financial Liabilities Fair value through net income Derivative liabilities - current $ (2.6) $ — $ (0.5) $ (2.1) $ (2.6) Derivative liabilities - deferred (24.0) — — (24.0) (24.0) Fair value through regulatory assets/liabilities Derivative liabilities - current (9.0) — (0.6) (8.4) (9.0) Derivative liabilities - deferred (63.6) — — (63.6) (63.6) Amortized cost Commercial paper (d) (72.5) — (72.5) — (72.5) Unsecured notes (e) (1,446.8) — (1,613.5) — (1,613.5) Total Liabilities $ (1,618.5) $ — $ (1,687.1) $ (98.1) $ (1,785.2) (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At December 31, 2020 Financial assets Fair value through net income Cash equivalents (a) $ 3.2 $ 3.2 $ — $ — $ 3.2 Rabbi trust investments (b) 22.0 22.0 — — 22.0 Derivative asset - current 2.1 — 0.7 1.4 2.1 Derivative asset - deferred 4.5 — — 4.5 4.5 Fair value through regulatory assets/liabilities Derivative asset - current 2.9 — 0.9 2.0 2.9 Derivative asset - deferred 6.8 — — 6.8 6.8 Amortized cost Other long-term receivables (c) 1.4 — 1.4 — 1.4 Total Assets $ 42.9 $ 25.2 $ 3.0 $ 14.7 $ 42.9 Financial Liabilities Fair value through net income Derivative liabilities - current $ (0.4) $ — $ — $ (0.4) (0.4) Derivative liabilities - deferred (26.8) — — (26.8) (26.8) Fair value through regulatory assets/liabilities Derivative liabilities - current (6.7) — (0.3) (6.4) (6.7) Derivative liabilities - deferred (61.8) — (0.7) (61.1) (61.8) Amortized cost Commercial paper (d) (285.0) — (285.0) — (285.0) Unsecured notes (e) (1,446.9) — (1,779.8) — (1,779.8) Total Liabilities $ (1,827.6) $ — $ (2,065.8) $ (94.7) $ (2,160.5) (a) Cash equivalents represent the amounts invested in money market funds and were included in "Cash and cash equivalents" of the accompanying balance sheets. (b) Rabbi Trust investments are invested in money market funds. At March 31, 2021, carrying amount of $2.1 million and $13.8 million was included in "Current assets — Other" and "Deferred charges and other assets — Other" of the accompanying balance sheets, respectively; At December 31, 2020, carrying amount of $6.7 million and $15.3 million was included in "Current assets — Other" and "Deferred charges and other assets — Other", respectively. (c) Amount represents a long-term receivable from one of our trading partners related to the Antero contract at December 31, 2020. The receivable became current and netted against the payable to the trading partner in "Account payable and other accrued liabilities" on the accompanying balance sheets at March 31, 2021. (d) The balance at March 31, 2021 included $72.5 million located in “Long-term debt” on the accompanying balance sheets. The balance at December 31, 2020 included $185.0 million located in "Notes payable", and $100.0 million located in “Long-term debt” on the accompanying balance sheets. (e) Includes adjustments for current maturities and unamortized discounts, as applicable. The amount was included in "Long-term debt" on the accompanying balance sheets.
Quantitative Information about Level 3 Fair Value Measurements	The following table includes quantitative information about the significant unobservable inputs used in the fair value measurement of our Level 3 financial instruments and the respective fair values of the net derivative asset and liability positions. Quantitative Information about Level 3 Fair Value Measurements (In millions) Net Fair Value Valuation Techniques Unobservable Inputs Weighted Average Range March 31, 2021 $(76.80) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) $(0.41) $(1.168)-$1.963 December 31, 2020 $(80.00) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) $(0.36) $(0.910)-$2.073
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs	The following table presents a reconciliation of changes in net fair value of Level 3 derivative instruments measured at fair value on a recurring basis. Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs Three Months Ended March 31, (In millions) 2021 2020 Balance at beginning of period $ (80.0) $ (84.8) Realized and unrealized gains (losses) Recorded to income 2.4 3.1 Recorded to regulatory assets — Gas costs (5.4) 9.1 Settlements 6.2 1.4 Balance at end of period $ (76.8) $ (71.2)
Unrealized Gains (Losses) Recorded for Level 3 Measurements	The following table presents the unrealized gains (losses) attributable to Level 3 derivative instruments measured at fair value on a recurring basis. Unrealized Gains (Losses) Recorded for Level 3 Measurements Three Months Ended March 31, (In millions) 2021 2020 Recorded to income — Utility cost of gas $ 1.6 $ 2.3 Recorded to regulatory assets — Gas costs (6.3) 7.6 Total $ (4.7) $ 9.9

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Gas Balancing Service Charges	The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Gas Balancing Service Charges (In millions) Three Months Ended March 31, 2021 2020 Gas balancing service charge $ 7.7 $ 6.6

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income	The following table shows the changes in accumulated other comprehensive income (AOCI) by component for the reporting periods. Changes in Accumulated Other Comprehensive Income by Component Three Months Ended March 31, (In thousands) 2021 2020 Beginning Balance $ 1,577 $ 4,576 Amortization of prior service credit (a)(b) (81) (304) Amortization of actuarial loss (a)(b)(c) 34 781 Actuarial gain arising during the period (a) 1,436 1,910 Current-period other comprehensive income 1,389 2,387 Income tax expense related to pension and other post-retirement benefit plans retained in AOCI (c) 367 620 Ending Balance $ 2,599 $ 6,343 (a) The accumulated other comprehensive income components are included in the computation of net periodic benefit cost. (b) Amortization of prior service cost and amortization of actuarial loss represent the amounts reclassified out of AOCI to “Other income (expense)-net” of statements of operations for the reporting periods. (c) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the MRVA used in the determination of net periodic pension and other post-retirement benefit plan costs. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. Refer to Note 1 — Accounting Policies for further discussion.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2021
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	The following table details the changes in operating assets and liabilities from operating activities, cash payments that have been included in the determination of earnings and non-cash investing and financing activities. (In thousands) Three Months Ended March 31, 2021 2020 CHANGES IN OPERATING ASSETS AND LIABILITIES Receivables $ (14,583) $ 53,278 (Receivables from) Payables to associated companies — net 127,218 11,649 Gas costs and other regulatory assets/liabilities — net (5,648) (43,613) Storage gas 41,611 56,430 Prepaid taxes 5,712 3,711 Accounts payable and other accrued liabilities (36,860) (59,144) Customer deposits and advance payments (13,185) (6,949) Accrued taxes 31 5,499 Other current assets 5,756 10,273 Other current liabilities (365) (243) Deferred gas costs — net 33,063 24,874 Deferred assets — other 2,019 (1,014) Deferred liabilities — other (2,427) (1,463) Pension and other post-retirement benefits (5,613) (4,245) Changes in operating assets and liabilities $ 136,729 $ 49,043 SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION Income taxes paid (refunded) — net $ — $ (3,880) Interest paid including interest for finance leases $ 31,437 $ 30,965 Cash paid for amounts included in the measurement of operating lease liabilities $ 1,535 $ 1,490 SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES: Right-of-use assets obtained in exchange for new operating lease liabilities $ 1,788 $ — Right-of-use assets obtained in exchange for new finance lease liabilities $ 425 $ — Capital expenditure accruals included in accounts payable and other accrued liabilities $ 44,996 $ 45,817
Reconciliation of cash, cash equivalents and restricted cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within Washington Gas’ balance sheets that sums to the total of such amounts shown on the statements of cash flows. (In thousands) March 31, 2021 March 31, 2020 Cash and cash equivalents $ 11,056 $ 42,418 Restricted cash included in Current assets-Other 2,083 11,332 Restricted cash included in Deferred charges and other assets-Other 13,826 28,113 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 26,965 $ 81,863

Accounting Policies - Change in

Accounting Policies - Change in Accounting Policy (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income (expense) — net	$ 9,583	$ 5,332
Income tax expense	34,397	32,046
Net income (loss)	133,614	127,759
Other comprehensive income	1,022	1,767
Comprehensive income (loss)	$ 134,636	129,526
Accrued/deferred pension and other post-retirement benefit cost (benefit)		(1,797)
Deferred income taxes — net		32,196
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income (expense) — net		3,070
Income tax expense		31,459
Net income (loss)		126,084
Other comprehensive income		1,941
Comprehensive income (loss)		128,025
Accrued/deferred pension and other post-retirement benefit cost (benefit)		465
Deferred income taxes — net		31,609
Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income (expense) — net		2,262
Income tax expense		587
Net income (loss)		1,675
Other comprehensive income		(174)
Comprehensive income (loss)		1,501
Accrued/deferred pension and other post-retirement benefit cost (benefit)		(2,262)
Deferred income taxes — net		$ 587

Credit Losses - Narrative (Deta

Credit Losses - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2020	Mar. 31, 2021	Jan. 01, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	$ 27,283	$ 32,401
Relief funds	$ 7,700
Unused funds		5,400
Recorded to regulatory asset due to COVID-19		$ 6,300
Cumulative effect of adoption | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses			$ 1,500
Decrease in retained earnings			$ 1,500

Credit Losses - Rollforward of

Credit Losses - Rollforward of Allowance Accounts (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019
Account Receivables and Unbilled Revenue
Provision	$ 7,345	$ 5,874
Accounting standards update	Accounting Standards Update 2016-13	Accounting Standards Update 2016-13	Accounting Standards Update 2016-13
Account Receivables and Unbilled Revenue
Account Receivables and Unbilled Revenue
Balance, beginning of period	$ 27,300	$ 18,700
Provision	7,500	5,900
Write offs	(2,800)	(7,500)
Recoveries	400	300
Balance, end of period	32,400	18,800	$ 18,700
Account Receivables and Unbilled Revenue | Cumulative effect of adoption
Account Receivables and Unbilled Revenue
Balance, beginning of period	0	1,400
Balance, end of period			1,400
Asset Optimization
Account Receivables and Unbilled Revenue
Balance, beginning of period	100	0
Provision	(100)	0
Write offs	0	0
Recoveries	0	0
Balance, end of period	0	100	0
Asset Optimization | Cumulative effect of adoption
Account Receivables and Unbilled Revenue
Balance, beginning of period	$ 0	$ 100
Balance, end of period			$ 100

Revenue from Contracts With C_3

Revenue from Contracts With Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 559,200	$ 458,300
Revenue from alternative revenue programs	21,600	40,600
Other	1,700	2,800
Total revenue from other sources	23,300	43,400
Total Operating Revenue	582,496	501,735
Gas and transportation sales | Gas sold and delivered
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	442,600	346,300
Gas and transportation sales | Gas delivered for others
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	102,900	97,600
Gas and transportation sales | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,800	13,700
Other revenues
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 900	$ 700

Revenue From Contracts With C_4

Revenue From Contracts With Customers - Contract Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Unbilled revenues	$ 86.8		$ 112.7
Contract assets at January 1	16.1	$ 44.2
Contract assets at March 31	6.7	46.1
Increase (decrease) in contract assets	$ (9.4)	$ 1.9

Accounts Payable and Other Ac_3

Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts Payable and Accrued Liabilities [Abstract]
Accounts payable—trade	$ 168.7	$ 201.2
Employee benefits and payroll accruals	10.2	22.3
Wages payable	20.8	19.5
Accrued interest	3.4	18.4
Other accrued liabilities	20.1	31.1
Total	$ 223.2	292.5
Antero contract
Loss Contingencies [Line Items]
Loss contingency accrual		$ 12.5

Short-Term Debt - Commitment Cr

Short-Term Debt - Commitment Credit Available (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Less: Commercial Paper outstanding		$ (285,000,000)
Credit facility
Short-term Debt [Line Items]
Unsecured revolving credit facility	$ 450,000,000	450,000,000
Less: Commercial Paper outstanding	(72,500,000)	(285,000,000)
Net committed credit available	$ 377,500,000	$ 165,000,000
Weighted average interest rate	0.23%	0.31%
Revolving credit facility additional borrowings	$ 100,000,000
Revolving credit facility maximum borrowing capacity	$ 550,000,000

Short-Term Debt - Additional In

Short-Term Debt - Additional Information (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Commercial paper		$ 285,000,000
Carrying Amount
Short-term Debt [Line Items]
Commercial paper	$ 72,500,000
Long-term debt
Short-term Debt [Line Items]
Commercial paper	100,000,000	100,000,000
Note payable and project financing
Short-term Debt [Line Items]
Commercial paper		185,000,000
Credit facility
Short-term Debt [Line Items]
Outstanding bank loans	0	0
Commercial paper	$ 72,500,000	$ 285,000,000

Long Term Debt (Details)

Long Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Long Term Debt [LIne Items]
Total Principal Amounts of Long-Term Debt	$ 1,518.5	$ 1,546
Unamortized premium (discount)	12.3	12.5
Unamortized debt expense	(11.5)	(11.6)
Non-current finance lease liability	0.7	0.3
Total Carrying Amount of Long-Term Debt	$ 1,520	$ 1,547.2
Weighted average interest rate	4.46%	4.46%
Unsecured Notes
Long Term Debt [LIne Items]
Total Principal Amounts of Long-Term Debt	$ 1,446	$ 1,446
Commercial Paper
Long Term Debt [LIne Items]
Total Principal Amounts of Long-Term Debt	$ 72.5	$ 100

Components of Total Equity - (D

Components of Total Equity - (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,855,925	$ 1,578,592
Net income (loss)	133,614	127,759
Other comprehensive income	1,022	1,767
Capital contribution from parent	0	125,000
Dividends Abstract
Common stock dividends declared	(25,000)	(25,000)
Ending Balance	$ 1,965,561	$ 1,806,575	$ 1,578,592
Accounting standards update	Accounting Standards Update 2016-13	Accounting Standards Update 2016-13	Accounting Standards Update 2016-13
Cumulative effect of adoption
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		$ (1,543)
Dividends Abstract
Ending Balance			$ (1,543)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	46,479,536	46,479,536
Beginning Balance	$ 46,479	$ 46,479
Dividends Abstract
Ending Balance (in shares)	46,479,536	46,479,536	46,479,536
Ending Balance	$ 46,479	$ 46,479	$ 46,479
Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,204,273	979,273
Capital contribution from parent	0	125,000
Dividends Abstract
Ending Balance	1,204,273	1,104,273	979,273
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	603,596	548,264
Net income (loss)	133,614	127,759
Dividends Abstract
Common stock dividends declared	(25,000)	(25,000)
Ending Balance	712,210	649,480	548,264
Retained Earnings | Cumulative effect of adoption
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		(1,543)
Dividends Abstract
Ending Balance			(1,543)
Accumulated Other Comprehensive Income, Net of Taxes
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,577	4,576
Other comprehensive income	1,022	1,767
Dividends Abstract
Ending Balance	$ 2,599	$ 6,343	$ 4,576

Pension and Other Post-retire_3

Pension and Other Post-retirement Benefit Plans - Components of Net Periodic Benefit Cost Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3.1	$ 3.2
Interest cost	7.6	8.9
Expected return on plan assets	(10.7)	(10.8)
Recognized prior service cost (credit)	0.1	0.1
Recognized actuarial loss (gain)	0.3	2.4
Settlement charge	1	1.1
Net periodic benefit cost (income)	1.4	4.9
Allocation to affiliates	0	(0.3)
Adjusted net periodic benefit cost (income)	1.4	4.6
Amount allocated to construction projects	(0.6)	(0.4)
Amount charged (credited) to expense	0.8	4.2
Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.6	1.3
Interest cost	2	2.3
Expected return on plan assets	(5.7)	(5.9)
Recognized prior service cost (credit)	(3.4)	(3.4)
Recognized actuarial loss (gain)	(1.2)	(0.5)
Settlement charge	0	0
Net periodic benefit cost (income)	(6.7)	(6.2)
Allocation to affiliates	0.2	0.4
Adjusted net periodic benefit cost (income)	(6.5)	(5.8)
Amount allocated to construction projects	(0.3)	(0.2)
Amount charged (credited) to expense	$ (6.8)	$ (6)

Pension and Other Post-Retire_4

Pension and Other Post-Retirement Benefit Plans - Narrative (Details) - Rabbi Trusts - DB SERP - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan assets	$ 12.7	$ 18.8
Other assets, current
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan assets	2.1	6.7
Other noncurrent assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan assets	$ 10.6	$ 12.1

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Commitments and Contingencies [Line Items]
Operation and maintenance expenses	$ 99,583	$ 102,678
Derivative asset - deferred	97,468		$ 99,793
Environmental response costs
Commitments and Contingencies [Line Items]
Derivative asset - deferred	7,200		7,400
Environmental response costs | Reserve for Environmental Costs
Commitments and Contingencies [Line Items]
Accrual for environmental loss contingencies	10,200		10,300
Estimated maximum liability	30,600		30,600
Environmental response costs | Reserve for Environmental Costs | Anacosta River Study
Commitments and Contingencies [Line Items]
Estimated maximum liability	19,100
Environmental response costs | Reserve for Environmental Costs | East Station Property
Commitments and Contingencies [Line Items]
Estimated maximum liability	8,000
Merger agreement, circumstance 2
Commitments and Contingencies [Line Items]
Other commitments payable	$ 9,400
Merger agreement, circumstance 2 | Future hiring
Commitments and Contingencies [Line Items]
Operation and maintenance expenses			$ 2,400
Regulatory commitments, term			5 years
Merger agreement, circumstance 2 | Extend natural gas service
Commitments and Contingencies [Line Items]
Operation and maintenance expenses			$ 70,000
Regulatory commitments, term			10 years
Merger agreement, circumstance 2 | Future leak mitigation
Commitments and Contingencies [Line Items]
Operation and maintenance expenses			$ 8,000
Regulatory commitments, term			3 years

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)counterparty	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Collaborative arrangement expenses	$ 1.3	$ 1
Right to reclaim cash	3.1		$ 2.8
Derivative, collateral, obligation to return cash	$ 0.1		$ 0.2
Number of counterparties | counterparty	3
Concentration risk credit risk financial instrument exposure	$ 32.6

Derivatives - Net Margins for A

Derivatives - Net Margins for Asset Optimization (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Realized gain	$ 2.9	$ 2.3
Unrealized gain	5.3	6.1
Net margin gain	$ 8.2	$ 8.4

Derivatives - Open Positions on

Derivatives - Open Positions on Derivative Instruments (Details) - BTU BTU in Millions	Mar. 31, 2021	Dec. 31, 2020
Asset optimization & trading
Derivative [Line Items]
Natural gas derivative transaction, volume	10,353	10,471
Other risk-management activities
Derivative [Line Items]
Natural gas derivative transaction, volume	794	881

Derivatives - Balance Sheet Cla

Derivatives - Balance Sheet Classification of Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross amounts of recognized assets/(liabilities)	$ 25.8	$ 17.8
Gross amounts offset in balance sheet	(0.4)	(1.5)
Netting of collateral	0	0
Net amounts presented on balance sheet	25.4	16.3
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross amounts of recognized assets/(liabilities)	(99.6)	(98.8)
Gross amounts offset in balance sheet	0.4	1.5
Netting of collateral	0	1.6
Net amounts presented on balance sheet	(99.2)	(95.7)
Total, gross amounts of recognized assets/(liabilities)	(73.8)	(81)
Total, gross amounts offset in balance sheet	0	0
Total, netting of collateral	0	1.6
Total	(73.8)	(79.4)
Derivative liabilities	99.2	95.7
Current assets—Derivatives
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	10.6	5
Deferred charges and other assets—Derivatives
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	14.8	11.3
Current liabilities—Derivatives
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	(11.6)	(7.1)
Derivative liabilities	11.6	7.1
Deferred credits—Derivatives
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	(87.6)	(88.6)
Derivative liabilities	$ 87.6	$ 88.6

Derivatives - Gains and Losses

Derivatives - Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Gains and (Losses) on Derivative Instruments
Total	$ (7.3)	$ 12
Recorded to income-Utility cost of gas
Gains and (Losses) on Derivative Instruments
Recorded to income	0.7	3.1
Recorded to regulatory assets-Gas costs
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets	$ (8)	$ 8.9

Derivatives - Credit Risk Conti

Derivatives - Credit Risk Contingent Features (Details) - Credit Risk Contract - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative liabilities with credit-risk-contingent features	$ 0.1	$ 0.7
Maximum potential collateral requirements	$ 0.1	$ 0.6

Fair Value Measurements - Under

Fair Value Measurements - Under the Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Financial assets
Cash equivalents	$ 200	$ 3,200
Rabbi trust investments	15,900	22,000
Derivative asset - current	10,605	5,049
Derivative asset - deferred	14,788	11,263
Other long-term receivables		1,400
Total Assets	41,500	42,900
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(11,641)	(7,053)
Fair value through net income, Derivative liabilities - deferred	(87,624)	(88,559)
Commercial paper		(285,000)
Unsecured debt	(1,613,500)	(1,779,800)
Total Liabilities	(1,785,200)	(2,160,500)
Restricted cash, current	2,083		$ 11,332
Restricted cash, noncurrent	13,826		$ 28,113
Long-term debt	1,520,000	1,547,200
Commercial Paper
Financial Liabilities
Commercial paper	(72,500)	(285,000)
Long-term debt	72,500	100,000
Level 1
Financial assets
Cash equivalents	200	3,200
Rabbi trust investments	15,900	22,000
Other long-term receivables		0
Total Assets	16,100	25,200
Financial Liabilities
Unsecured debt	0	0
Total Liabilities	0	0
Level 1 | Commercial Paper
Financial Liabilities
Commercial paper	0	0
Level 2
Financial assets
Cash equivalents	0	0
Rabbi trust investments	0	0
Other long-term receivables		1,400
Total Assets	4,100	3,000
Financial Liabilities
Unsecured debt	(1,613,500)	(1,779,800)
Total Liabilities	(1,687,100)	(2,065,800)
Level 2 | Commercial Paper
Financial Liabilities
Commercial paper	(72,500)	(285,000)
Level 3
Financial assets
Cash equivalents	0	0
Rabbi trust investments	0	0
Other long-term receivables		0
Total Assets	21,300	14,700
Financial Liabilities
Unsecured debt	0	0
Total Liabilities	(98,100)	(94,700)
Level 3 | Commercial Paper
Financial Liabilities
Commercial paper	0	0
Carrying Amount
Financial assets
Cash equivalents	200	3,200
Rabbi trust investments	15,900	22,000
Other long-term receivables		1,400
Total Assets	41,500	42,900
Financial Liabilities
Commercial paper	(72,500)
Unsecured debt	(1,446,800)	(1,446,900)
Total Liabilities	(1,618,500)	(1,827,600)
Carrying Amount | Commercial Paper
Financial Liabilities
Commercial paper	(72,500)	(285,000)
Derivative assets
Financial assets
Derivative asset - current	4,300	2,100
Derivative asset - deferred	6,600	4,500
Derivative assets | Level 1
Financial assets
Derivative asset - current	0	0
Derivative asset - deferred	0	0
Derivative assets | Level 2
Financial assets
Derivative asset - current	400	700
Derivative asset - deferred	1,200	0
Derivative assets | Level 3
Financial assets
Derivative asset - current	3,900	1,400
Derivative asset - deferred	5,400	4,500
Derivative assets | Carrying Amount
Financial assets
Derivative asset - current	4,300	2,100
Derivative asset - deferred	6,600	4,500
Regulatory assets
Financial assets
Derivative asset - current	6,300	2,900
Derivative asset - deferred	8,200	6,800
Regulatory assets | Level 1
Financial assets
Derivative asset - current	0	0
Derivative asset - deferred	0	0
Regulatory assets | Level 2
Financial assets
Derivative asset - current	600	900
Derivative asset - deferred	1,900	0
Regulatory assets | Level 3
Financial assets
Derivative asset - current	5,700	2,000
Derivative asset - deferred	6,300	6,800
Regulatory assets | Carrying Amount
Financial assets
Derivative asset - current	6,300	2,900
Derivative asset - deferred	8,200	6,800
Derivative liabilities
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(2,600)	(400)
Fair value through net income, Derivative liabilities - deferred	(24,000)	(26,800)
Derivative liabilities | Level 1
Financial Liabilities
Fair value through net income, Derivative liabilities - current	0	0
Fair value through net income, Derivative liabilities - deferred	0	0
Derivative liabilities | Level 2
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(500)	0
Fair value through net income, Derivative liabilities - deferred	0	0
Derivative liabilities | Level 3
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(2,100)	(400)
Fair value through net income, Derivative liabilities - deferred	(24,000)	(26,800)
Derivative liabilities | Carrying Amount
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(2,600)	(400)
Fair value through net income, Derivative liabilities - deferred	(24,000)	(26,800)
Regulatory liabilities
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(9,000)
Fair value through net income, Derivative liabilities - deferred	(63,600)
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(6,700)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(61,800)
Regulatory liabilities | Level 1
Financial Liabilities
Fair value through net income, Derivative liabilities - current	0
Fair value through net income, Derivative liabilities - deferred	0
Fair value through regulatory assets/liabilities, Derivative liabilities - current		0
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		0
Regulatory liabilities | Level 2
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(600)
Fair value through net income, Derivative liabilities - deferred	0
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(300)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(700)
Regulatory liabilities | Level 3
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(8,400)
Fair value through net income, Derivative liabilities - deferred	(63,600)
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(6,400)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(61,100)
Regulatory liabilities | Carrying Amount
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(9,000)
Fair value through net income, Derivative liabilities - deferred	(63,600)
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(6,700)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(61,800)
Other assets, current
Financial Liabilities
Restricted cash, current	2,100	6,700
Deferred charges and other assets—Derivatives
Financial Liabilities
Restricted cash, noncurrent	$ 13,800	15,300
Note payable and project financing
Financial Liabilities
Commercial paper		$ (185,000)

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative information (Details) - Natural Gas Related Derivatives $ in Millions	Mar. 31, 2021USD ($)$ / dekatherm	Dec. 31, 2020USD ($)$ / dekatherm	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Fair Value | $	$ (76.8)	$ (80)	$ (71.2)	$ (84.8)
Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Fair Value | $	$ (76.8)	$ (80)
Discounted Cash Flow | Weighted Average | Natural Gas Basis Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input price (in dollars per share)	(0.41)	(0.36)
Discounted Cash Flow | Maximum | Natural Gas Basis Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input price (in dollars per share)	1.963	2.073
Discounted Cash Flow | Minimum | Natural Gas Basis Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Input price (in dollars per share)	(1.168)	(0.910)

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation with Level 3 Inputs (Details) - Natural Gas Related Derivatives - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs
Beginning of period	$ (80)	$ (84.8)
Recorded to income	2.4	3.1
Recorded to regulatory assets — Gas costs	(5.4)	9.1
Settlements	6.2	1.4
End of period	$ (76.8)	$ (71.2)

Fair Value Measurements - Unrea

Fair Value Measurements - Unrealized Gains and Losses Recorded for Level 3 Measurements (Details) - Natural Gas Related Derivatives - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets	$ (5.4)	$ 9.1
Total	(4.7)	9.9
Recorded to income-Utility cost of gas
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	1.6	2.3
Regulatory asset-gas costs member
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets	$ (6.3)	$ 7.6

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Operation and maintenance	$ 99,583	$ 102,678
Contract asset	6,700	46,100	$ 16,100	$ 44,200
Payables to associated companies	32,870		29,526
Receivables from associated companies	600		112,200
Payables to associated companies	600		600
Receivables from associated companies	4,243		128,254
Hampshire Gas Company
Related Party Transaction [Line Items]
Operation and maintenance	2,100	2,000
WGL Energy Systems | Energy management services projects not complete
Related Party Transaction [Line Items]
Payables to associated companies	6,700		16,100
Shared services | Parent Company
Related Party Transaction [Line Items]
Operation and maintenance	5,000	5,000
WGL Energy Services
Related Party Transaction [Line Items]
Payables to associated companies	1,400
Gas balancing service charge	7,700	$ 6,600
Receivables from associated companies			2,000
Related party purchased receivables	$ 8,400		$ 6,900

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI, Net of Tax [Roll Forward]
Beginning Balance	$ 1,855,925	$ 1,578,592
Current-period other comprehensive income	1,389	2,387
Income tax expense related to pension and other post-retirement benefit plans retained in AOCI	367	620
Ending Balance	1,965,561	1,806,575
Accumulated other comprehensive income (loss)
AOCI, Net of Tax [Roll Forward]
Beginning Balance	1,577	4,576
Ending Balance	2,599	6,343
Amortization of prior service cost
AOCI, Net of Tax [Roll Forward]
Reclassification	(81)	(304)
Amortization of actuarial gain (loss)
AOCI, Net of Tax [Roll Forward]
Reclassification	34	781
Actuarial gain arising during the period	$ 1,436	$ 1,910

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
CHANGES IN OPERATING ASSETS AND LIABILITIES
Receivables	$ (14,583)	$ 53,278
(Receivables from) Payables to associated companies — net	127,218	11,649
Gas costs and other regulatory assets/liabilities — net	(5,648)	(43,613)
Storage gas	41,611	56,430
Prepaid taxes	5,712	3,711
Accounts payable and other accrued liabilities	(36,860)	(59,144)
Customer deposits and advance payments	(13,185)	(6,949)
Accrued taxes	31	5,499
Other current assets	5,756	10,273
Other current liabilities	(365)	(243)
Deferred gas costs — net	33,063	24,874
Deferred assets — other	2,019	(1,014)
Deferred liabilities — other	(2,427)	(1,463)
Pension and other post-retirement benefits	(5,613)	(4,245)
Changes in operating assets and liabilities	136,729	49,043
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid (refunded) — net	0	(3,880)
Interest paid including interest for finance leases	31,437	30,965
Cash paid for amounts included in the measurement of operating lease liabilities	1,535	1,490
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Right-of-use assets obtained in exchange for new operating lease liabilities	1,788	0
Right-of-use assets obtained in exchange for new finance lease liabilities	425	0
Capital expenditure accruals included in accounts payable and other accrued liabilities	44,996	45,817
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	11,056	42,418	$ 1
Restricted cash included in Current assets-Other	2,083	11,332
Restricted cash included in Deferred charges and other assets-Other	13,826	28,113
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 26,965	$ 81,863	$ 21,962	$ 61,148