Washington Gas Light (WGLCP) 10-Q 6 Nov 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	0-49807
Entity Registrant Name	WASHINGTON GAS LIGHT CO
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	53-0162882
Entity Address, Address Line One	1000 Maine Ave., S.W.
Entity Address, City or Town	Washington
Entity Address, State or Province	DC
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	2020
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment
At original cost	$ 6,237,537	$ 5,962,866
Accumulated depreciation and amortization	(1,656,788)	(1,579,718)
Net property, plant and equipment	4,580,749	4,383,148
Current Assets
Cash and cash equivalents	1,214	17,069
Receivables (net of allowance for doubtful accounts of $26,517 and $18,708, respectively)	210,649	400,891
Gas costs and other regulatory assets	18,643	9,894
Materials and supplies—principally at average cost	20,682	20,184
Storage gas	72,077	87,977
Prepaid taxes	30,479	34,576
Other prepayments	18,176	33,867
Receivables from associated companies	8,920	12,421
Derivatives	4,665	6,553
Other	7,666	19,619
Total current assets	393,171	643,051
Deferred Charges and Other Assets
Gas costs	69,076	98,717
Pension and other post-retirement benefits	39,966	44,078
Other	99,267	84,886
Prepaid post-retirement benefits	372,307	366,508
Right of use asset	38,963	40,004
Derivatives	9,113	10,370
Other	27,805	30,620
Total deferred charges and other assets	656,497	675,183
Total Assets	5,630,417	5,701,382
Capitalization
Common shareholder’s equity	1,756,332	1,578,592
Long-term debt	1,431,390	1,430,949
Total capitalization	3,187,722	3,009,541
Current Liabilities
Notes payable	169,959	299,483
Accounts payable and other accrued liabilities	216,958	267,408
Customer deposits and advance payments	38,267	40,052
Gas costs and other regulatory liabilities	31,761	105,399
Accrued taxes	28,281	23,781
Payables to associated companies	63,176	57,923
Operating lease liability	5,846	5,850
Derivatives	9,622	4,069
Other	34,196	30,032
Total current liabilities	598,066	833,997
Deferred Credits
Deferred income taxes	518,208	464,717
Accrued pensions and benefits	116,299	115,837
Asset retirement obligations	213,265	206,820
Regulatory liabilities
Accrued asset removal costs	242,921	254,429
Other post-retirement benefits	184,370	195,670
Excess deferred taxes and other	389,972	404,700
Operating lease liability	52,087	53,642
Derivatives	76,407	97,695
Other	51,100	64,334
Total deferred credits	1,844,629	1,857,844
Commitments and Contingencies (Note 11)
Total Capitalization and Liabilities	$ 5,630,417	$ 5,701,382

Condensed Balance Sheets (Una_2

Condensed Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for credit losses	$ 26,517	$ 18,708

Condensed Statements of Operati

Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
OPERATING REVENUES	$ 143,383	$ 122,305	$ 856,284	$ 914,442
OPERATING EXPENSES
Utility cost of gas	20,846	33,433	221,301	331,285
Operation and maintenance	94,175	101,195	291,885	300,433
Depreciation and amortization	36,298	34,383	108,485	106,623
General taxes and other assessments	27,992	26,344	110,006	106,709
Total Operating Expenses	179,311	195,355	731,677	845,050
OPERATING INCOME (LOSS)	(35,928)	(73,050)	124,607	69,392
Other income (expense) — net	4,070	2,619	16,419	4,556
Interest expense	16,088	15,575	49,011	45,092
INCOME (LOSS) BEFORE INCOME TAXES	(47,946)	(86,006)	92,015	28,856
INCOME TAX EXPENSE (BENEFIT)	(11,324)	(19,530)	15,477	4,280
NET INCOME (LOSS)	(36,622)	(66,476)	76,538	24,576
Dividends on preferred stock	0	0	0	660
NET INCOME (LOSS) APPLICABLE TO COMMON STOCK	$ (36,622)	$ (66,476)	$ 76,538	$ 23,916

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ (36,622)	$ (66,476)	$ 76,538	$ 24,576
Pension and other post-retirement benefit plans
Change in prior service cost	(292)	(163)	(924)	(486)
Change in actuarial net gain	1,713	442	4,628	2,596
Total pension and other post-retirement benefit plans	1,421	279	3,704	2,110
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME	366	(700)	959	572
OTHER COMPREHENSIVE INCOME	1,055	979	2,745	1,538
COMPREHENSIVE INCOME (LOSS)	$ (35,567)	$ (65,497)	$ 79,283	$ 26,114

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
OPERATING ACTIVITIES
Net income	$ 76,538	$ 24,576
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and amortization	108,485	106,623
Amortization of:
Other regulatory assets and liabilities — net	6,044	5,583
Debt related costs	1,072	1,128
Deferred income taxes — net	15,908	6,375
Accrued/deferred pension and other post-retirement benefit cost (benefit)	(6,758)	1,793
Compensation expense related to stock-based awards	2,156	2,275
Provision for doubtful accounts	11,101	10,615
Unrealized (gain) loss on derivative contracts	(5,501)	(128)
Amortization of investment tax credits	(431)	(494)
Other non-cash charges (credits) — net	364	1,226
Changes in operating assets and liabilities (Note 16)	53,708	94,572
Net Cash Provided by Operating Activities	262,686	254,144
FINANCING ACTIVITIES
Capital contribution from parent	175,000	0
Long-term debt issued	0	298,482
Debt issuance costs	(10)	(2,756)
Notes payable issued (retired) — net	(129,524)	(179,000)
Dividends on common stock and preferred stock	(75,000)	(75,227)
Net Cash Provided by (Used in) Financing Activities	(29,534)	41,499
INVESTING ACTIVITIES
Capital expenditures	(265,060)	(318,895)
Net Cash Used in Investing Activities	(265,060)	(318,895)
INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(31,908)	(23,252)
Cash, Cash Equivalents, and Restricted Cash at Beginning of the Period	61,148	71,423
Cash, Cash equivalents and Restricted Cash at End of the Period	$ 29,240	$ 48,171

Accounting Policies

Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Accounting Policies	ACCOUNTING POLICIES Basis of Presentation Following a 2018 merger agreement, Washington Gas became an indirect, majority owned subsidiary of, among other entities, AltaGas and WGL. In connection with the Merger, WGL formed a wholly owned subsidiary, Wrangler SPE LLC (Wrangler SPE), a bankruptcy remote, special purpose entity to own the common stock of Washington Gas. In addition, WGL owns all of the shares of common stock of certain affiliated non-utility subsidiaries. On December 20, 2019, Washington Gas redeemed all the outstanding shares of its preferred stock, after which, Washington Gas became an indirect, wholly owned subsidiary of AltaGas and WGL. 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, 2019. 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, 2020 and 2019. 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 year ended December 31, 2019. 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. The change uses the fair value approach for the fixed income investments and related derivatives, which represent a separate asset class of the plan assets, compared to the prior method that utilized a calculated value for all investments where gains and losses arising from changes in fair value were deferred and amortized into the calculation of the MRVA over a period of five years. The MRVA is used in the calculation of the expected return on assets and the recognized actuarial gain or loss components of net periodic benefit cost. The gains and losses for other plan assets will continue to be deferred and amortized into the MRVA over a five-year period. We believe that using the fair value approach for the fixed income investments and related derivatives in our plan assets is preferable because the Company will immediately recognize the gains and losses of the fixed income investments and derivatives in MRVA rather than deferring them over a five-year period, which results in a better matching of the change in fixed income investments and the related pension obligations. We have retrospectively applied this change in accounting principle to all applicable prior period financial information presented herein as required. The change in accounting principle increased retained earnings $9.4 million and decreased accumulated other comprehensive income (loss), net of taxes, $0.4 million, with a net increase of $9.0 million in common shareholder’s equity at January 1, 2019. The following tables summarize the effect of the change in accounting principle on the primary financial statement line items on our condensed balance sheets, 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 8 — Components of Total Equity , Note 10 — Pension and Other Post — Retirement Benefit Plans, and Note 15 — Accumulated Other Comprehensive Income (Loss) . September 30, 2020 December 31, 2019 (In thousands) Without Change Adjustment As Reported (with change) As Previously Reported Adjustment As Adjusted Condensed Balance Sheets Regulatory assets — Pension and other post-retirement benefits $ 31,337 $ 8,629 $ 39,966 $ 39,435 $ 4,643 $ 44,078 Common shareholder’s equity $ 1,745,434 $ 10,898 $ 1,756,332 $ 1,572,196 $ 6,396 $ 1,578,592 Regulatory liabilities — Other post-retirement benefits $ 190,460 $ (6,090) $ 184,370 $ 199,665 $ (3,995) $ 195,670 Deferred income taxes $ 514,387 $ 3,821 $ 518,208 $ 462,475 $ 2,242 $ 464,717 Components of Total Equity Retained earnings (a) $ 536,505 $ 11,754 $ 548,259 $ 541,535 $ 6,729 $ 548,264 Accumulated other comprehensive income (loss), net of taxes (a) $ 8,177 $ (856) $ 7,321 $ 4,909 $ (333) $ 4,576 (a) Retained earnings and Accumulated other comprehensive income (loss), net of taxes, are reported in Note 8 — Components of Total Equity. Three Months Ended Nine Months Ended (In thousands) Without Change Adjustment As Reported (with change) Without Change Adjustment As Reported (with change) Condensed Statements of Operations Other income (expense) — net $ 1,808 $ 2,262 $ 4,070 $ 9,632 $ 6,787 $ 16,419 Income tax expense (benefit) $ (11,911) $ 587 $ (11,324) $ 13,715 $ 1,762 $ 15,477 Net income (loss) $ (38,297) $ 1,675 $ (36,622) $ 71,513 $ 5,025 $ 76,538 Condensed Statements of Comprehensive Income Other comprehensive income (loss), net of taxes $ 1,229 $ (174) $ 1,055 $ 3,268 $ (523) $ 2,745 Comprehensive income (loss) $ (37,068) $ 1,501 $ (35,567) $ 74,781 $ 4,502 $ 79,283 Three Months Ended Nine Months Ended (In thousands) As Previously Reported Adjustment As Adjusted As Previously Reported Adjustment As Adjusted Condensed Statements of Operations Other income (expense) — net $ 3,533 $ (914) $ 2,619 $ 7,298 $ (2,742) $ 4,556 Income tax expense (benefit) $ (19,293) $ (237) $ (19,530) $ 4,992 $ (712) $ 4,280 Net income (loss) $ (65,799) $ (677) $ (66,476) $ 26,606 $ (2,030) $ 24,576 Condensed Statements of Comprehensive Income Other comprehensive income (loss), net of taxes $ 942 $ 37 $ 979 $ 1,428 $ 110 $ 1,538 Comprehensive income (loss) $ (64,857) $ (640) $ (65,497) $ 28,034 $ (1,920) $ 26,114 Nine Months Ended Nine Months Ended (In thousands) Without Change Adjustment As Reported (with change) As Previously Reported Adjustment As Adjusted Condensed Statements of Cash Flows Net income $ 71,513 $ 5,025 $ 76,538 $ 26,606 $ (2,030) $ 24,576 ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES Accrued/deferred pension and other post-retirement benefit cost (benefit) $ 29 $ (6,787) $ (6,758) $ (949) $ 2,742 $ 1,793 Deferred income taxes — net $ 14,146 $ 1,762 $ 15,908 $ 7,087 $ (712) $ 6,375 Accounting Standards Adopted in the Calendar Year and Other Newly Issued Accounting Standards The following tables represent accounting standards adopted by Washington Gas during the nine months ended September 30, 2020, and other newly issued accounting standards that will be adopted by Washington Gas in the future. ACCOUNTING STANDARDS ADOPTED IN CALENDAR YEAR 2020 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, including other subsequent ASUs further amending and clarifying the guidance. For credit losses on financial instruments measured at amortized cost, this standard changes the current incurred loss impairment methodology to an expected loss methodology and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. In addition, entities may make a one-time irrevocable election on certain eligible financial instruments to elect fair value treatment on an instrument-by-instrument basis. January 1, 2020 Cash equivalents, accounts receivable, unbilled revenue, and contract assets are within the scope of the new standard. Upon adoption, we recorded an increase to our allowance for doubtful accounts and a reduction to retained earnings of $1.5 million. See Note 2 - Credit Losses for further information and the new required disclosures. ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement This update modifies the disclosure requirements on fair value measurements. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Topic 808 does not provide comprehensive recognition or measurement guidance for collaborative arrangements. This update clarifies the interaction between Topic 606, Revenue from Contracts with Customers and Topic 808. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2019-01, Leases (Topic 842) Codification Improvements This update addresses the determination of the fair value of the underlying asset by lessors that are not manufacturers or dealers, provides guidance for the presentation of the statement of cash flows for sales-type and direct financing leases, and clarifies transition disclosures related to the adoption of ASC 842. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2019-04, Codification Improvements to Topic 326, Financial The amendments in this ASU provide clarification and improve the codification in recently issued accounting standards. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2020-03, Codification Improvements to Financial Instruments This Update makes technical corrections and minor improvements to the guidance on financial instruments. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required date of adoption Effect on the financial statements or other significant matters ASU 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans This standard modifies the disclosure requirements related to defined benefit pension and other postretirement plans. Early adoption is permitted. December 31, 2020 It is not expected that the adoption of this standard will have a material effect on our financial statements. 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 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting 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 made and to hedging relationships existing as of or entered into on or after the date of adoption and through December 31, 2022. December 31, 2022 We have not yet elected to adopt this ASU as of September 30, 2020 and are assessing the impact the adoption of this standard will have on our financial statements.

Credit Losses

Credit Losses	9 Months Ended
	Sep. 30, 2020
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. The CECL model requires the expected credit losses to consider past events, including historical experience, current conditions and reasonable and supportable forecasts. When measuring credit losses, financial assets with similar risk characteristics should be pooled, and credit losses should be recognized over the contractual term of the financial asset. In addition, entities may make a one-time irrevocable election on certain eligible financial instruments to elect fair-value treatment on an instrument-by-instrument basis. Our assessment concluded that our cash equivalents, accounts receivables, unbilled revenue, contract assets, and a long term receivable from one of 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. Prior periods presented for comparative purposes are not adjusted. Upon implementation of ASU 2016-13 Utility 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 14 — Related Party Transactions for further information. Washington Gas Asset Optimization : The Utility 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 credits, 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 the Utility 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. Washington Gas also has a long-term receivable from a trading partner totaling $1.4 million in “Deferred charges and other assets — Other”, of which no portion of the balance is past due. The trading partner was evaluated and assigned an internal credit rating in accordance with our credit policy. An allowance for doubtful accounts is recorded based on historical default rates published by external credit rating agencies and a rate commensurate with the period in which the receivable is expected to be collected. Estimated credit loss reserve was recorded as a reduction to “Deferred charges and other assets — Other”. COVID-19 : On March 11, 2020, the World Health Organization declared the outbreak of a strain of novel coronavirus disease, COVID-19, a global pandemic. Governments in affected areas in which we operate have imposed a number of measures designed to contain the outbreak, including business closures, travel restrictions, quarantines and cancellations of gatherings and events. These measures have resulted in widespread challenges to businesses and the job market. The increased unemployment rates could impact the ability of the Company’s customers to pay for services. As a result of regulatory orders, we have temporarily suspended customer disconnections for non-payment, temporarily suspended collection activities and temporarily waived assessing and billing late payment fees. 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 Public Service Commission of Maryland (PSC of MD) and the 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. For the three and nine months ended September 30, 2020, Washington Gas has recorded total $4.7 million and $7.7 million in deferrals of incremental bad debt expense to COVID-19 regulatory assets across all three jurisdictions, respectively. As of September 30, 2020, 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 in 2020, economic conditions, receivables aging, and considerations of past economic downturns, the actions the company is taking to assist customers with past due balances, and the corresponding allowance for credit losses and customer account write-offs. Based on this evaluation, we have concluded that the allowance for credit losses as of September 30, 2020 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 Nine Months Ended (In millions) Account Receivables and Unbilled Revenue Asset Optimization Account Receivables and Unbilled Revenue Asset Optimization Balance, beginning of period $ 23.2 $ 0.1 $ 18.7 $ — Provision 1.3 — 11.1 — Recorded to regulatory asset due to COVID-19 4.7 — 7.7 — Write offs (3.0) — (13.8) — Recoveries 0.3 — 1.4 — Adjustment upon adoption of ASC 326 — — 1.4 0.1 Balance, end of period $ 26.5 $ 0.1 $ 26.5 $ 0.1

Revenue from Contracts With Cus

Revenue from Contracts With Customers	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	REVENUE FROM CONTRACTS WITH CUSTOMERS The Company recognizes revenue from contracts with customers to depict the transfer of goods or services to customers at an amount it expects to be entitled to 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 Nine Months Ended (In millions) 2020 2019 2020 2019 Revenue from contracts with customers Gas and transportation sales Gas sold and delivered $ 91.2 $ 70.7 $ 592.8 $ 665.1 Gas delivered for others 39.5 33.4 186.5 186.8 Other 3.6 10.9 23.6 34.4 Other revenues 1.3 1.4 2.1 4.2 Total revenue from contracts with customers $ 135.6 $ 116.4 $ 805.0 $ 890.5 Other sources of revenue Revenue from alternative revenue programs (a) $ 7.6 $ 3.6 $ 47.7 $ 14.9 Leasing revenue 0.2 0.2 0.5 0.5 Other (b) — 2.1 3.1 8.5 Total revenue from other sources $ 7.8 $ 5.9 $ 51.3 $ 23.9 Total Operating Revenue $ 143.4 $ 122.3 $ 856.3 $ 914.4 (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 $28.5 million and $116.3 million are included within "Receivables" on Washington Gas' balance sheets at September 30, 2020 and December 31, 2019, 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. Washington Gas did not have any contract liabilities at September 30, 2020 and 2019. 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 opening and closing balances of contract assets from contracts with customers for the reporting periods, which were included within "Receivables" on Washington Gas' balance sheets. (In millions) 2020 2019 (a) Contract assets at January 1 $ 44.2 $ 85.3 Contract assets at September 30 $ 51.8 $ 40.5 Increase (decrease) in contract assets $ 7.6 $ (44.8) ( a) Decrease in contract asset in 2019 was due to the sale of the contract asset. Refer to "Project financing" in Note 14 — Related party transactions for detail discussion.

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	LEASES Washington Gas has operating leases as a lessee for our corporate headquarters and other offices, communication tower space, and certain office equipment. The Company also has lessor leases for land, office space and communication tower space that are classified as operating leases. Washington Gas has elected not to separate the lease and non-lease components for its building leases. The leases generally have options to terminate the leases with notice prior to the end of the lease term based on the contract terms. The lease agreements do not contain material residual value guarantees. For information on the lease income recognized during the period, see the Disaggregated Revenue by Type of Service table in Note 3 — Revenue from Contracts with Customers.
Leases	LEASES Washington Gas has operating leases as a lessee for our corporate headquarters and other offices, communication tower space, and certain office equipment. The Company also has lessor leases for land, office space and communication tower space that are classified as operating leases. Washington Gas has elected not to separate the lease and non-lease components for its building leases. The leases generally have options to terminate the leases with notice prior to the end of the lease term based on the contract terms. The lease agreements do not contain material residual value guarantees. For information on the lease income recognized during the period, see the Disaggregated Revenue by Type of Service table in Note 3 — Revenue from Contracts with Customers.

Accounts Payable and Other Accr

Accounts Payable and Other Accrued Liabilities	9 Months Ended
	Sep. 30, 2020
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) September 30, 2020 December 31, 2019 Accounts payable—trade $ 135.3 $ 154.3 Employee benefits and payroll accruals 20.9 39.3 Wages payable 25.6 22.2 Accrued interest 3.2 17.3 Other accrued liabilities (a) 32.0 34.4 Total $ 217.0 $ 267.5 (a) Amount includes $12.3 million and $11.7 million estimated liability associated with the Antero judgment at September 30, 2020 and December 31, 2019, respectively. Refer to Note 11 — Commitments and Contingencies for further information.

Short-Term Debt

Short-Term Debt	9 Months Ended
	Sep. 30, 2020
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 September 30, 2020 and December 31, 2019. (In millions) September 30, 2020 December 31, 2019 Committed credit agreements Unsecured revolving credit facility, expires July 19, 2024 (a) $450.0 $450.0 Less: Commercial Paper outstanding (b) (270.0) (400.0) Net committed credit available $180.0 $50.0 Weighted average interest rate 0.27% 2.04% (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 September 30, 2020 and December 31, 2019, there were no outstanding bank loans from Washington Gas’ revolving credit facilities. Commercial Paper The total commercial paper carrying value was $270.0 million and $399.5 million at September 30, 2020 and December 31, 2019, respectively. At both September 30, 2020 and December 31, 2019, Washington Gas classified $100.0 million of our commercial paper balance as "Long-term debt" on Washington Gas' balance sheets due to its ability and intent to refinance these balances on a long-term basis. Accordingly, $170.0 million and $299.5 million of commercial paper remained in “Notes payable” at September 30, 2020 and December 31, 2019, respectively.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2020
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 September 30, 2020 and December 31, 2019. Long Term Debt Outstanding (In millions) September 30, 2020 December 31, 2019 Washington Gas Unsecured Notes (a) $ 1,346.0 $ 1,346.0 Commercial Paper 100.0 100.0 Total Principal Amounts of Long-Term Debt $ 1,446.0 $ 1,446.0 Unamortized discount (4.2) (4.3) Unamortized debt expense (10.4) (10.8) Less—current maturities — — Total Long-Term Debt $ 1,431.4 $ 1,430.9 Weighted average interest rate (b) 4.52 % 4.52 % (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. The following table shows the issuances of Washington Gas' unsecured notes for the three and nine months ended September 30, 2019. There was no retirement of long-term debt for the three and nine months ended September 30, 2019. There were no issuances or retirements of long-term debt for the three and nine months ended September 30, 2020. Washington Gas' Unsecured Notes Issuances (In millions) Principal (a) Interest Rate (b) Effective Cost (b) Nominal Maturity Date Three and Nine Months Ended September 30, 2019 Issuances: 09/13/2019 $ 300.00 3.65 % 3.72 % 9/15/2049 (a) Represents face amount of notes. (b) Represents the interest rate and effective cost at the trade date of the debt.

Components of Total Equity

Components of Total Equity	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Components of Total Equity	COMPONENTS OF TOTAL EQUITY Common Stock Paid-In Capital Retained Earnings (b) Accumulated Other Comprehensive Income/(Loss), Net of Taxes (b) (In thousands, except shares) Shares Amount Total (b) Three Months Ended September 30, 2020 Balance at June 30, 2020 46,479,536 $ 46,479 $ 1,104,273 $ 609,881 $ 6,266 $ 1,766,899 Net income (loss) — — — (36,622) — (36,622) Other comprehensive income — — — — 1,055 1,055 Capital contribution from parent — — 50,000 — — 50,000 Dividends declared: Common stock — — — (25,000) — (25,000) Balance at September 30, 2020 46,479,536 $ 46,479 $ 1,154,273 $ 548,259 $ 7,321 $ 1,756,332 Three Months Ended September 30, 2019 Balance at June 30, 2019 46,479,536 $ 46,479 $ 979,273 $ 593,276 $ (6,547) $ 1,612,481 Net income (loss) — — — (66,476) — (66,476) Other comprehensive income — — — — 979 979 Dividends declared: — Common stock — — — — — — Preferred stock — — — — — — Balance at September 30, 2019 46,479,536 $ 46,479 $ 979,273 $ 526,800 $ (5,568) $ 1,546,984 Nine Months Ended September 30, 2020 Balance at December 31, 2019 46,479,536 $ 46,479 $ 979,273 $ 548,264 $ 4,576 1,578,592 Net income — — — 76,538 — 76,538 Other comprehensive income — — — — 2,745 2,745 Capital contribution from parent — — 175,000 — — 175,000 ASU 2016-13 implementation (a) — — — (1,543) — (1,543) Dividends declared: Common stock — — — (75,000) — (75,000) Balance at September 30, 2020 46,479,536 $ 46,479 $ 1,154,273 $ 548,259 $ 7,321 $ 1,756,332 Nine Months Ended September 30, 2019 Balance at December 31, 2018 46,479,536 $ 46,479 $ 979,273 $ 552,884 $ (7,106) $ 1,571,530 Net income — — — 24,576 — 24,576 Other comprehensive income — — — — 1,538 1,538 Dividends declared: Common stock — — — (50,000) — (50,000) Preferred stock — — — (660) — (660) Balance at September 30, 2019 46,479,536 $ 46,479 $ 979,273 $ 526,800 $ (5,568) $ 1,546,984 (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 market-related value of assets 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.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES WGL and its wholly owned subsidiaries, including Washington Gas, are 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 September 30, 2020 and December 31, 2019, Washington Gas recorded a $5.5 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. The Coronavirus Aid, Relief and Economic Security Act ("CARES Act") was signed into law on March 27, 2020. The CARES Act includes various income and payroll tax provisions. Washington Gas will benefit from certain provisions such as the deferral of payment of applicable payroll taxes. As of September 30, 2020, we have determined that there is no material impact to our financial statements. However, we continue to assess and quantify the impact of the legislation to our financial statements.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefit Plans	9 Months Ended
	Sep. 30, 2020
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) Three Months Ended September 30, 2020 2019 (c) (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 3.1 $ 1.3 $ 3.0 $ 1.3 Interest cost 8.9 2.3 10.2 3.0 Expected return on plan assets (10.6) (5.9) (10.5) (6.1) Recognized prior service cost (credit) 0.1 (3.4) 0.1 (3.9) Recognized actuarial loss (gain) 1.8 (0.5) 1.9 — Settlement charge 2.4 — — — Net periodic benefit cost (income) 5.7 (6.2) 4.7 (5.7) Allocation to affiliates (0.4) 0.5 (0.4) 0.5 Adjusted net periodic benefit cost (income) 5.3 (5.7) 4.3 (5.2) Amount allocated to construction projects (0.5) (0.2) (0.4) (0.2) Amount charged (credited) to expense $ 4.8 $ (5.9) $ 3.9 $ (5.4) Nine Months Ended September 30, 2020 2019 (c) (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 9.4 $ 4.0 $ 9.1 $ 3.8 Interest cost 26.6 6.9 30.7 9.0 Expected return on plan assets (31.9) (17.7) (31.4) (18.2) Recognized prior service cost (credit) 0.2 (10.2) 0.3 (11.7) Recognized actuarial loss (gain) 5.7 (1.5) 5.9 — Settlement charge (a) 3.6 — 4.3 — Net periodic benefit cost (income) 13.6 (18.5) 18.9 (17.1) Allocation to affiliates (1.2) 1.6 (1.3) 1.8 Adjusted net periodic benefit cost (income) 12.4 (16.9) 17.6 (15.3) Amount allocated to construction projects (1.6) (0.7) (1.2) (0.6) Amount deferred as regulatory asset (liability)-net allocations (b) — — 0.7 — Amount charged (credited) to expense $ 10.8 $ (17.6) $ 17.1 $ (15.9) (a) Amounts relate to partial settlement charges associated with lump sum payments from the Washington Gas’ defined benefit supplemental executive retirement plan (DB SERP). (b) Amount represents the amortization of previously unrecovered costs of the applicable pension benefits or the health and life benefits as approved in the District of Columbia through 2019. (c) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the market-related value of assets 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.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
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. Refer to Note 13- Commitments and Contingencies to the Financial Statements in Form 10-K for the calendar year ended December 31, 2019 for future payments. There were no significant changes to contractual obligations that are out of the normal course of business during the nine months ended September 30, 2020. Merger Commitments In connection with the Merger, Washington Gas and AltaGas have made commitments related to the terms of settlement agreement with PSC of DC and the conditions of approval from PSC of MD and SCC of VA. As of September 30, 2020, the remaining unpaid liability for previously expensed merger commitments was $15.9 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. 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. Antero Contract In June 2019, a jury trial was held in the County Court for Denver, Colorado to consider a contractual dispute relating to gas pricing between Washington Gas and its affiliate WGL Midstream and Antero Resources Corporation (Antero). Following the trial, the jury returned a verdict in favor of Antero for $95.9 million, of which $11.2 million was against Washington Gas, and $84.7 million against WGL Midstream. Following the official entry of the judgment, the Company filed an appeal on August 16, 2019. Arguments on the appeal occurred on November 4, 2020. As a result of this verdict, it was determined that a loss contingency is probable and Washington Gas recorded an estimated liability and recognized a loss in June 2019. In addition, Washington Gas recorded a receivable from our trading partner, and a receivable related to sharing with our customers as the contract relates to asset optimization. Washington Gas has been accruing interest expense on a monthly basis associated with the liability since June 2019. At September 30, 2020, the estimated liability with court fees and accrued interest was $12.3 million recorded in “Accounts payable and accrued liabilities” on Washington Gas' balance sheets. The net receivable from our trading partner was $1.3 million in “Deferred charges and other assets-Other”, and sharing with customers was $5.0 million in “Regulatory assets - Gas costs” on the balance sheets. For the nine months ended September 30, 2020 the interest expense associated with the legal liability was immaterial. For the nine months ending September 30, 2019, the net pre-tax loss recorded as a result of the verdict was $3.0 million in “Utility cost of gas” on Washington Gas’ statements of operations. 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. Maryland Show-Cause Order . On April 23, 2019, the National Transportation and Safety Board (NTSB) held a hearing during which it found, among other things, that the probable cause of the August 10, 2016, explosion and fire at an apartment complex on Arliss Street in Silver Spring, Maryland “was the failure of an indoor mercury service regulator with an unconnected vent line that allowed natural gas into the meter room where it accumulated and ignited from an unknown ignition source. Contributing to the accident was the location of the mercury service regulators where leak detection by odor was not readily available.” Washington Gas disagrees with the NTSB’s probable cause findings. Following this hearing, on June 10, 2019, the NTSB issued an accident report. Following the NTSB hearing, on September 5, 2019, the PSC of MD ordered the Company, within 30 days, to (i) provide a detailed response to the NTSB’s probable cause findings, and (ii) provide evidence regarding the status of a 2003 mercury regulator replacement program, and if the program was not completed, to show cause why the Commission should not impose a civil penalty on the Company. The Company timely responded to the PSC of MD’s Show-Cause Order, providing a detailed response to the NTSB’s probable cause findings, providing evidence regarding the status of its 2003 mercury regulator replacement program and demonstrating cause why the PSC of MD should not impose a civil penalty on the Company. Following the Company’s response, certain intervenors filed written comments and a public hearing was held on the matter, with some intervenors and members of the public advocating for penalties against the Company. The Company filed its rejoinder comments and the Show-Cause Order is working its way through the regulatory proceeding process with the PSC of MD. An evidentiary hearing was conducted on September 24 – 25, 2020. Initial briefs were filed on October 28, 2020 and reply briefs will be filed on November 13, 2020. Management believes that the likelihood of a civil penalty is probable and has accrued $330,000 to reflect the minimum liability as a result of delinquent mercury regulator replacement status reporting. Though the Company is unable to estimate the maximum possible penalty, other parties have recommended penalties ranging from $620,500 (PSC of MD Staff, which argued the Company should pay a minimum penalty for failing to provide annual reports detailing progress in replacing the mercury regulators) to $123.3 million (Office of People's Counsel, which argued the Company should absorb all costs of removal and relocation of mercury service regulators and pay a fine of $25,000 per day for each day mercury service regulators remain on the Company’s system). 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 September 30, 2020 and December 31, 2019, Washington Gas reported a liability of $10.4 million and $10.7 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 September 30, 2020 and December 31, 2019, Washington Gas estimated the maximum liability associated with all of its sites to be approximately $30.7 million. 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 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 is scheduled to submit a Remedial Investigative Report by December 29, 2020. 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. 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 September 30, 2020 and December 31, 2019, Washington Gas reported a regulatory asset of $6.8 million and $7.0 million, respectively, for the portion of environmental response costs that are expected to be recoverable in future rates.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2020
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 $2.4 million and $2.5 million for the three months ended September 30, 2020 and 2019, respectively, and $5.8 million and $3.8 million for the nine months ended September 30, 2020 and 2019, 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. All physically and financially settled contracts under our asset optimization program are reported on a net basis in the statements of operations in “Utility cost of gas”. Total net margins recorded to “Utility cost of gas” after sharing and management fees associated with all asset optimization transactions for the three months ended September 30, 2020 was a net gain of $5.1 million including an unrealized loss of $1.3 million. During the three months ended September 30, 2019, we recorded a net loss of $1.2 million including an unrealized loss of $6.5 million . During the nine months ended September 30, 2020, we recorded a net gain of $19.7 million including an unrealized gain of $5.5 million. During the nine months ended September 30, 2019, we recorded a net gain of $8.3 million including an unrealized gain of $0.1 million and the $3.0 million loss related to the Antero Contract. Refer to Note 11 - Commitments and Contingencies for further discussion of the Antero Contract. 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 September 30, 2020 and December 31, 2019. Absolute Notional Amounts of Open Positions on Derivative Instruments September 30, 2020 December 31, 2019 Natural Gas (In millions of therms) Asset optimization & trading 10,726.0 11,671.0 Other risk-management activities 915.0 976.0 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 September 30, 2020 Derivative assets (a) $ 20.2 $ (6.4) $ — $ 13.8 Derivative liabilities (b) (92.4) 6.4 — $ (86.0) Net derivative assets (liabilities) $ (72.2) $ — $ — $ (72.2) December 31, 2019 Derivative assets (a) $ 13.0 $ 4.0 $ — $ 17.0 Derivative liabilities (b) (104.0) (4.0) 6.2 (101.8) Net derivative assets (liabilities) $ (91.0) $ — $ 6.2 $ (84.8) (a) Derivative assets at September 30, 2020 include $4.7 million recorded in "Current assets — Derivatives" and $9.1 million in" Deferred charges and other assets — Derivatives" on Washington Gas' balance sheets; Derivative assets at December 31, 2019 include $6.6 million recorded in "Current assets —Derivatives" and $10.4 million in" Deferred charges and other assets — Derivatives" on Washington Gas' balance sheets. (b) Derivative liabilities at September 30, 2020 include $9.6 million recorded in "Current liabilities — Derivatives " and $76.4 million recorded in " Deferred credits — Derivatives" on Washington Gas' balance sheets; Derivative liabilities at December 31, 2019 include $4.1 million recorded in "Current liabilities — Derivatives " and $97.7 million recorded in " Deferred credits — Derivatives" on Washington Gas' balance sheets. Gains and (Losses) on Derivatives The following tables present all gains and losses associated with derivative instruments for the three and nine months ended September 30, 2020 and 2019. Gains and (Losses) on Derivative Instruments (In millions) Three Months Ended Nine Months Ended 2020 2019 2020 2019 Recorded to income-Utility cost of gas $ (0.3) $ (5.8) $ 6.2 $ (0.1) Recorded to regulatory assets-Gas costs (7.1) (9.6) 9.8 4.8 Total $ (7.4) $ (15.4) $ 16.0 $ 4.7 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 September 30, 2020 and December 31, 2019, Washington Gas had $1.0 million and $5.2 million, respectively, in collateral deposits posted with counterparties that are not offset against derivative asset and liabilities. At September 30, 2020 and December 31, 2019, Washington Gas had $0.1 million and $0.1 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 September 30, 2020 and December 31, 2019, Washington Gas was not required 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 September 30, 2020 and December 31, 2019, respectively. Potential Collateral Requirements for Derivative Liabilities (In millions) September 30, 2020 December 31, 2019 Derivative liabilities with credit-risk-contingent features $ 0.2 $ 0.4 Maximum potential collateral requirements $ 0.2 $ 0.4 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 September 30, 2020, one counterparty represented over 10% of Washington Gas’ credit exposure to wholesale derivative counterparties for a total credit risk of $15.1 million.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
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. (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At September 30, 2020 Financial assets Fair value through net income Cash equivalents (a) $ 0.8 $ 0.8 $ — $ — $ 0.8 Rabbi trust investments (b) 28.0 28.0 — — 28.0 Derivative asset - current 1.9 — 0.2 1.7 1.9 Derivative asset - deferred 3.7 — — 3.7 3.7 Fair value through regulatory assets/liabilities Derivative asset - current 2.8 — 0.4 2.4 2.8 Derivative asset - deferred 5.4 — — 5.4 5.4 Amortized cost Other long-term receivables (c) 1.3 — 1.3 — 1.3 Total Assets $ 43.9 $ 28.8 $ 1.9 $ 13.2 $ 43.9 Financial Liabilities Fair value through net income Derivative liabilities - current $ (2.4) $ — $ (0.2) $ (2.2) $ (2.4) Derivative liabilities - deferred (22.8) — — (22.8) (22.8) Fair value through regulatory assets/liabilities Derivative liabilities - current (7.2) — (0.4) (6.8) (7.2) Derivative liabilities - deferred (53.6) — — (53.6) (53.6) Amortized cost Commercial paper (d) (270.0) — (270.0) — (270.0) Unsecured notes (e) (1,331.4) — (1,605.0) — (1,605.0) Total Liabilities $ (1,687.4) $ — $ (1,875.6) $ (85.4) $ (1,961.0) (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At December 31, 2019 Financial assets Fair value through net income Cash equivalents (a) $ 11.0 $ 11.0 $ — $ — $ 11.0 Rabbi trust investments (b) 44.1 44.1 — — 44.1 Derivative asset - current 2.6 — 0.1 2.5 2.6 Derivative asset - deferred 4.1 — 0.2 3.9 4.1 Fair value through regulatory assets/liabilities Derivative asset - current 4.0 — — 4.0 4.0 Derivative asset - deferred 6.3 — 0.3 6.0 6.3 Amortized cost Other long-term receivables (c) 1.3 — 1.3 — 1.3 Total Assets $ 73.4 $ 55.1 $ 1.9 $ 16.4 $ 73.4 Financial Liabilities Fair value through net income Derivative liabilities - current $ (0.7) $ — $ — $ (0.7) (0.7) Derivative liabilities - deferred (28.4) — — (28.4) (28.4) Fair value through regulatory assets/liabilities Derivative liabilities - current (3.4) — (0.6) (2.8) (3.4) Derivative liabilities - deferred (69.3) — — (69.3) (69.3) Amortized cost Commercial paper (d) (399.5) — (399.5) — (399.5) Unsecured notes (e) (1,330.9) — (1,480.8) — (1,480.8) Total Liabilities $ (1,832.2) $ — $ (1,880.9) $ (101.2) $ (1,982.1) (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 September 30, 2020, carrying amount of $7.5 million and $20.5 million was included in "Current assets — Other" and "Deferred charges and other assets — Other" of the accompanying balance sheets, respectively; At December 31, 2019, carrying amount of $19.5 million and $24.6 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 discussed in Note 11 — Commitments and Contingencies. The carrying amount represents the long-term receivable net of allowance for doubtful accounts. (d) The balance at September 30, 2020 includes $170.0 million located in "Notes payable", and $100.0 million located in “Long-term debt” on the accompanying balance sheets. The balance at December 31, 2019 includes $299.5 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 (a) Range September 30, 2020 ($72.2) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($0.34) ($1.105)-$2.068 December 31, 2019 ($84.8) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) n/a ($0.905)-$2.523 (a) ASU 2018-13 has been applied prospectively, beginning with the interim period ending March 31, 2020. The average level 3 price was weighted by transaction volume. 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 Nine Months Ended (In millions) 2020 2019 2020 2019 Balance at beginning of period $ (65.8) $ (86.9) $ (84.8) $ (106.6) Realized and unrealized gains (losses) Recorded to income (0.2) (6.2) 5.2 (1.4) Recorded to regulatory assets — Gas costs (6.4) (10.1) 9.0 4.3 Transfers into Level 3 — (2.9) — (6.7) Transfers out of Level 3 — 2.9 — 7.9 Settlements 0.2 (3.1) (1.6) (3.8) Balance at end of period $ (72.2) $ (106.3) $ (72.2) $ (106.3) 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 Nine Months Ended (In millions) 2020 2019 2020 2019 Recorded to income — Utility cost of gas $ 0.2 $ (5.9) $ 8.6 $ 1.6 Recorded to regulatory assets — Gas costs (4.4) (10.2) 14.5 7.9 Total $ (4.2) $ (16.1) $ 23.1 $ 9.5

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
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 of the total shared service costs allocated to all of WGL's subsidiaries in "Payable to associated companies" and a receivable of the shared service costs allocated to WGL’s other subsidiaries in “Receivables from associated companies” on the balance sheets. Additionally, effective upon the approval by the SCC of Virginia in March 2020, Washington Gas began receiving 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 $5.3 million and $15.4 million were included in “Operation and maintenance” on the statements of operations for the three and nine months ended September 30, 2020, respectively, reflecting the corporate service cost allocated to Washington Gas. The net expenses of $5.0 million and $12.5 million were included in “Operation and maintenance” on the statements of operations for the three and nine months ended September 30, 2019, 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 September 30, 2020, Washington Gas recorded $51.8 million of contract assets in “Receivables” and a $51.8 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, 2019, Washington Gas recorded $44.2 million of contract assets in “Receivables” and a $44.2 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. In October 2018, WGL Energy Systems repaid $53.0 million historically drawn by Washington Gas from a third-party lender for Washington Gas' area-wide contract that the lender demanded repayment for due to delays in achieving final acceptance from the federal government agency customer. The $53.0 million was included in "Payables to associated companies" on Washington Gas' balance sheets at December 31, 2018. In February 2019, WGL sold the contract asset, and accordingly, Washington Gas reversed the associated amount in “Payables to associated companies” and “Receivables” on its balance sheets during the three months ended March 31. 2019. 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 $2.3 million and $6.4 million for three and nine months ended September 30, 2020, and $1.5 million and $5.5 million for the three and nine months ended September 30, 2019, 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. Other Related Party Transactions In connection with billing for unregulated third-party marketers, including WGL Energy Services, Inc., (WGL Energy Services), an indirect, wholly-owned subsidiary of WGL, 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. Washington Gas - Gas Balancing Service Charges Three Months Ended Nine Months Ended (In millions) 2020 2019 2020 2019 Gas balancing service charge $ 2.7 $ 2.9 $ 12.4 $ 14.9 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 $0.2 million and $2.1 million payable to WGL Energy Services at September 30, 2020 and December 31, 2019, respectively, related to an imbalance in gas volumes. The payables were recorded in "Accounts payable and other accrued liabilities" on Washington Gas' balance sheets.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table shows the changes in accumulated other comprehensive income (loss) (AOCI) by component for the reporting periods. Changes in Accumulated Other Comprehensive Income (Loss) by Component Three Months Ended Nine Months Ended (In thousands) 2020 2019 (c) 2020 2019 (c) Beginning Balance $ 6,266 $ (6,547) $ 4,576 $ (7,106) Amortization of prior service credit (a)(b) (292) (163) (924) (486) Amortization of actuarial loss (a)(b) 427 442 1,432 1,346 Actuarial gain (loss) arising during the period (a) 1,286 — 3,196 1,250 Current-period other comprehensive income 1,421 279 3,704 2,110 Income tax expense related to pension and other post-retirement benefit plans retained in AOCI 366 (700) 959 572 Ending Balance $ 7,321 $ (5,568) $ 7,321 $ (5,568) (a) The accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. (b) Amortization of prior service cost and amortization of actuarial gain (loss) represent the amounts reclassified out of AOCI to “Other income (expense)” 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 market-related value of assets 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	9 Months Ended
	Sep. 30, 2020
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. Nine Months Ended September 30, (In thousands) 2020 2019 CHANGES IN OPERATING ASSETS AND LIABILITIES Receivables $ 177,598 $ 174,986 (Receivables from) Payables to associated companies — net 8,754 6,402 Gas costs and other regulatory assets/liabilities — net (82,387) (8,253) Storage gas 15,900 11,479 Prepaid taxes 4,097 (3,791) Accounts payable and other accrued liabilities (67,114) (109,287) Customer deposits and advance payments (1,785) (11,511) Accrued taxes 4,500 6,830 Other current assets 20,226 5,077 Other current liabilities 4,163 (240) Deferred gas costs — net 16,360 49,379 Deferred assets — other (19,523) 11,807 Deferred liabilities — other (14,929) (26,879) Pension and other post-retirement benefits (12,152) (11,427) Changes in operating assets and liabilities $ 53,708 $ 94,572 SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION Income taxes paid (refunded) — net (2,880) 5,253 Interest paid 62,169 54,238 SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES: Extinguishment of project debt financing activities — net — (15,460) Capital expenditure accruals included in accounts payable and other accrued liabilities $ 52,643 $ 39,976 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) September 30, 2020 September 30, 2019 Cash and cash equivalents $ 1,214 $ 1 Restricted cash included in Current assets-Other 7,507 4,225 Restricted cash included in Deferred charges and other assets-Other 20,519 43,945 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 29,240 $ 48,171 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 September 30, 2020 and 2019. Refer to Note 10 — Pension and Other Post-Retirement Benefit Plans for further discussion of rabbi trusts.

Accounting Policies (Policies)

Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Consolidation	Following a 2018 merger agreement, Washington Gas became an indirect, majority owned subsidiary of, among other entities, AltaGas and WGL. In connection with the Merger, WGL formed a wholly owned subsidiary, Wrangler SPE LLC (Wrangler SPE), a bankruptcy remote, special purpose entity to own the common stock of Washington Gas. In addition, WGL owns all of the shares of common stock of certain affiliated non-utility subsidiaries. On December 20, 2019, Washington Gas redeemed all the outstanding shares of its preferred stock, after which, Washington Gas became an indirect, wholly owned subsidiary of AltaGas and WGL.
New Accounting Pronouncements	The following tables represent accounting standards adopted by Washington Gas during the nine months ended September 30, 2020, and other newly issued accounting standards that will be adopted by Washington Gas in the future. ACCOUNTING STANDARDS ADOPTED IN CALENDAR YEAR 2020 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, including other subsequent ASUs further amending and clarifying the guidance. For credit losses on financial instruments measured at amortized cost, this standard changes the current incurred loss impairment methodology to an expected loss methodology and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. In addition, entities may make a one-time irrevocable election on certain eligible financial instruments to elect fair value treatment on an instrument-by-instrument basis. January 1, 2020 Cash equivalents, accounts receivable, unbilled revenue, and contract assets are within the scope of the new standard. Upon adoption, we recorded an increase to our allowance for doubtful accounts and a reduction to retained earnings of $1.5 million. See Note 2 - Credit Losses for further information and the new required disclosures. ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement This update modifies the disclosure requirements on fair value measurements. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Topic 808 does not provide comprehensive recognition or measurement guidance for collaborative arrangements. This update clarifies the interaction between Topic 606, Revenue from Contracts with Customers and Topic 808. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2019-01, Leases (Topic 842) Codification Improvements This update addresses the determination of the fair value of the underlying asset by lessors that are not manufacturers or dealers, provides guidance for the presentation of the statement of cash flows for sales-type and direct financing leases, and clarifies transition disclosures related to the adoption of ASC 842. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2019-04, Codification Improvements to Topic 326, Financial The amendments in this ASU provide clarification and improve the codification in recently issued accounting standards. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2020-03, Codification Improvements to Financial Instruments This Update makes technical corrections and minor improvements to the guidance on financial instruments. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required date of adoption Effect on the financial statements or other significant matters ASU 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans This standard modifies the disclosure requirements related to defined benefit pension and other postretirement plans. Early adoption is permitted. December 31, 2020 It is not expected that the adoption of this standard will have a material effect on our financial statements. 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 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting 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 made and to hedging relationships existing as of or entered into on or after the date of adoption and through December 31, 2022. December 31, 2022 We have not yet elected to adopt this ASU as of September 30, 2020 and are assessing the impact the adoption of this standard will have on our financial statements.
Revenue from Contract with Customers	The Company recognizes revenue from contracts with customers to depict the transfer of goods or services to customers at an amount it expects to be entitled to 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.
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.
Income Taxes	WGL and its wholly owned subsidiaries, including Washington Gas, are 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.
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 $2.4 million and $2.5 million for the three months ended September 30, 2020 and 2019, respectively, and $5.8 million and $3.8 million for the nine months ended September 30, 2020 and 2019, 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.
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.

Accounting Policies (Tables)

Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
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 balance sheets, 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 8 — Components of Total Equity , Note 10 — Pension and Other Post — Retirement Benefit Plans, and Note 15 — Accumulated Other Comprehensive Income (Loss) . September 30, 2020 December 31, 2019 (In thousands) Without Change Adjustment As Reported (with change) As Previously Reported Adjustment As Adjusted Condensed Balance Sheets Regulatory assets — Pension and other post-retirement benefits $ 31,337 $ 8,629 $ 39,966 $ 39,435 $ 4,643 $ 44,078 Common shareholder’s equity $ 1,745,434 $ 10,898 $ 1,756,332 $ 1,572,196 $ 6,396 $ 1,578,592 Regulatory liabilities — Other post-retirement benefits $ 190,460 $ (6,090) $ 184,370 $ 199,665 $ (3,995) $ 195,670 Deferred income taxes $ 514,387 $ 3,821 $ 518,208 $ 462,475 $ 2,242 $ 464,717 Components of Total Equity Retained earnings (a) $ 536,505 $ 11,754 $ 548,259 $ 541,535 $ 6,729 $ 548,264 Accumulated other comprehensive income (loss), net of taxes (a) $ 8,177 $ (856) $ 7,321 $ 4,909 $ (333) $ 4,576 (a) Retained earnings and Accumulated other comprehensive income (loss), net of taxes, are reported in Note 8 — Components of Total Equity. Three Months Ended Nine Months Ended (In thousands) Without Change Adjustment As Reported (with change) Without Change Adjustment As Reported (with change) Condensed Statements of Operations Other income (expense) — net $ 1,808 $ 2,262 $ 4,070 $ 9,632 $ 6,787 $ 16,419 Income tax expense (benefit) $ (11,911) $ 587 $ (11,324) $ 13,715 $ 1,762 $ 15,477 Net income (loss) $ (38,297) $ 1,675 $ (36,622) $ 71,513 $ 5,025 $ 76,538 Condensed Statements of Comprehensive Income Other comprehensive income (loss), net of taxes $ 1,229 $ (174) $ 1,055 $ 3,268 $ (523) $ 2,745 Comprehensive income (loss) $ (37,068) $ 1,501 $ (35,567) $ 74,781 $ 4,502 $ 79,283 Three Months Ended Nine Months Ended (In thousands) As Previously Reported Adjustment As Adjusted As Previously Reported Adjustment As Adjusted Condensed Statements of Operations Other income (expense) — net $ 3,533 $ (914) $ 2,619 $ 7,298 $ (2,742) $ 4,556 Income tax expense (benefit) $ (19,293) $ (237) $ (19,530) $ 4,992 $ (712) $ 4,280 Net income (loss) $ (65,799) $ (677) $ (66,476) $ 26,606 $ (2,030) $ 24,576 Condensed Statements of Comprehensive Income Other comprehensive income (loss), net of taxes $ 942 $ 37 $ 979 $ 1,428 $ 110 $ 1,538 Comprehensive income (loss) $ (64,857) $ (640) $ (65,497) $ 28,034 $ (1,920) $ 26,114 Nine Months Ended Nine Months Ended (In thousands) Without Change Adjustment As Reported (with change) As Previously Reported Adjustment As Adjusted Condensed Statements of Cash Flows Net income $ 71,513 $ 5,025 $ 76,538 $ 26,606 $ (2,030) $ 24,576 ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES Accrued/deferred pension and other post-retirement benefit cost (benefit) $ 29 $ (6,787) $ (6,758) $ (949) $ 2,742 $ 1,793 Deferred income taxes — net $ 14,146 $ 1,762 $ 15,908 $ 7,087 $ (712) $ 6,375 The following tables represent accounting standards adopted by Washington Gas during the nine months ended September 30, 2020, and other newly issued accounting standards that will be adopted by Washington Gas in the future. ACCOUNTING STANDARDS ADOPTED IN CALENDAR YEAR 2020 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, including other subsequent ASUs further amending and clarifying the guidance. For credit losses on financial instruments measured at amortized cost, this standard changes the current incurred loss impairment methodology to an expected loss methodology and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. In addition, entities may make a one-time irrevocable election on certain eligible financial instruments to elect fair value treatment on an instrument-by-instrument basis. January 1, 2020 Cash equivalents, accounts receivable, unbilled revenue, and contract assets are within the scope of the new standard. Upon adoption, we recorded an increase to our allowance for doubtful accounts and a reduction to retained earnings of $1.5 million. See Note 2 - Credit Losses for further information and the new required disclosures. ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement This update modifies the disclosure requirements on fair value measurements. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 Topic 808 does not provide comprehensive recognition or measurement guidance for collaborative arrangements. This update clarifies the interaction between Topic 606, Revenue from Contracts with Customers and Topic 808. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2019-01, Leases (Topic 842) Codification Improvements This update addresses the determination of the fair value of the underlying asset by lessors that are not manufacturers or dealers, provides guidance for the presentation of the statement of cash flows for sales-type and direct financing leases, and clarifies transition disclosures related to the adoption of ASC 842. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2019-04, Codification Improvements to Topic 326, Financial The amendments in this ASU provide clarification and improve the codification in recently issued accounting standards. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. ASU 2020-03, Codification Improvements to Financial Instruments This Update makes technical corrections and minor improvements to the guidance on financial instruments. January 1, 2020 The adoption of this standard did not have a material effect on our financial statements. OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required date of adoption Effect on the financial statements or other significant matters ASU 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans This standard modifies the disclosure requirements related to defined benefit pension and other postretirement plans. Early adoption is permitted. December 31, 2020 It is not expected that the adoption of this standard will have a material effect on our financial statements. 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 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2020-04, Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting 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 made and to hedging relationships existing as of or entered into on or after the date of adoption and through December 31, 2022. December 31, 2022 We have not yet elected to adopt this ASU as of September 30, 2020 and are assessing the impact the adoption of this standard will have on our financial statements.

Credit Losses (Tables)

Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2020
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 Nine Months Ended (In millions) Account Receivables and Unbilled Revenue Asset Optimization Account Receivables and Unbilled Revenue Asset Optimization Balance, beginning of period $ 23.2 $ 0.1 $ 18.7 $ — Provision 1.3 — 11.1 — Recorded to regulatory asset due to COVID-19 4.7 — 7.7 — Write offs (3.0) — (13.8) — Recoveries 0.3 — 1.4 — Adjustment upon adoption of ASC 326 — — 1.4 0.1 Balance, end of period $ 26.5 $ 0.1 $ 26.5 $ 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 Nine Months Ended (In millions) Account Receivables and Unbilled Revenue Asset Optimization Account Receivables and Unbilled Revenue Asset Optimization Balance, beginning of period $ 23.2 $ 0.1 $ 18.7 $ — Provision 1.3 — 11.1 — Recorded to regulatory asset due to COVID-19 4.7 — 7.7 — Write offs (3.0) — (13.8) — Recoveries 0.3 — 1.4 — Adjustment upon adoption of ASC 326 — — 1.4 0.1 Balance, end of period $ 26.5 $ 0.1 $ 26.5 $ 0.1

Revenue from Contracts With C_2

Revenue from Contracts With Customers (Tables)	9 Months Ended
	Sep. 30, 2020
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 Nine Months Ended (In millions) 2020 2019 2020 2019 Revenue from contracts with customers Gas and transportation sales Gas sold and delivered $ 91.2 $ 70.7 $ 592.8 $ 665.1 Gas delivered for others 39.5 33.4 186.5 186.8 Other 3.6 10.9 23.6 34.4 Other revenues 1.3 1.4 2.1 4.2 Total revenue from contracts with customers $ 135.6 $ 116.4 $ 805.0 $ 890.5 Other sources of revenue Revenue from alternative revenue programs (a) $ 7.6 $ 3.6 $ 47.7 $ 14.9 Leasing revenue 0.2 0.2 0.5 0.5 Other (b) — 2.1 3.1 8.5 Total revenue from other sources $ 7.8 $ 5.9 $ 51.3 $ 23.9 Total Operating Revenue $ 143.4 $ 122.3 $ 856.3 $ 914.4 (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 opening and closing balances of contract assets from contracts with customers for the reporting periods, which were included within "Receivables" on Washington Gas' balance sheets. (In millions) 2020 2019 (a) Contract assets at January 1 $ 44.2 $ 85.3 Contract assets at September 30 $ 51.8 $ 40.5 Increase (decrease) in contract assets $ 7.6 $ (44.8) ( a) Decrease in contract asset in 2019 was due to the sale of the contract asset. Refer to "Project financing" in Note 14 — Related party transactions for detail discussion.

Accounts Payable and Other Ac_2

Accounts Payable and Other Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
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) September 30, 2020 December 31, 2019 Accounts payable—trade $ 135.3 $ 154.3 Employee benefits and payroll accruals 20.9 39.3 Wages payable 25.6 22.2 Accrued interest 3.2 17.3 Other accrued liabilities (a) 32.0 34.4 Total $ 217.0 $ 267.5 (a) Amount includes $12.3 million and $11.7 million estimated liability associated with the Antero judgment at September 30, 2020 and December 31, 2019, respectively. Refer to Note 11 — Commitments and Contingencies for further information.

Short-Term Debt (Tables)

Short-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2020
Short-term Debt [Abstract]
Committed Credit Available	The following is a summary of committed credit available at September 30, 2020 and December 31, 2019. (In millions) September 30, 2020 December 31, 2019 Committed credit agreements Unsecured revolving credit facility, expires July 19, 2024 (a) $450.0 $450.0 Less: Commercial Paper outstanding (b) (270.0) (400.0) Net committed credit available $180.0 $50.0 Weighted average interest rate 0.27% 2.04% (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)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table shows the long-term debt outstanding at September 30, 2020 and December 31, 2019. Long Term Debt Outstanding (In millions) September 30, 2020 December 31, 2019 Washington Gas Unsecured Notes (a) $ 1,346.0 $ 1,346.0 Commercial Paper 100.0 100.0 Total Principal Amounts of Long-Term Debt $ 1,446.0 $ 1,446.0 Unamortized discount (4.2) (4.3) Unamortized debt expense (10.4) (10.8) Less—current maturities — — Total Long-Term Debt $ 1,431.4 $ 1,430.9 Weighted average interest rate (b) 4.52 % 4.52 % (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. The following table shows the issuances of Washington Gas' unsecured notes for the three and nine months ended September 30, 2019. There was no retirement of long-term debt for the three and nine months ended September 30, 2019. There were no issuances or retirements of long-term debt for the three and nine months ended September 30, 2020. Washington Gas' Unsecured Notes Issuances (In millions) Principal (a) Interest Rate (b) Effective Cost (b) Nominal Maturity Date Three and Nine Months Ended September 30, 2019 Issuances: 09/13/2019 $ 300.00 3.65 % 3.72 % 9/15/2049 (a) Represents face amount of notes. (b) Represents the interest rate and effective cost at the trade date of the debt.

Components of Total Equity (Tab

Components of Total Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Schedule of Stockholders Equity	Common Stock Paid-In Capital Retained Earnings (b) Accumulated Other Comprehensive Income/(Loss), Net of Taxes (b) (In thousands, except shares) Shares Amount Total (b) Three Months Ended September 30, 2020 Balance at June 30, 2020 46,479,536 $ 46,479 $ 1,104,273 $ 609,881 $ 6,266 $ 1,766,899 Net income (loss) — — — (36,622) — (36,622) Other comprehensive income — — — — 1,055 1,055 Capital contribution from parent — — 50,000 — — 50,000 Dividends declared: Common stock — — — (25,000) — (25,000) Balance at September 30, 2020 46,479,536 $ 46,479 $ 1,154,273 $ 548,259 $ 7,321 $ 1,756,332 Three Months Ended September 30, 2019 Balance at June 30, 2019 46,479,536 $ 46,479 $ 979,273 $ 593,276 $ (6,547) $ 1,612,481 Net income (loss) — — — (66,476) — (66,476) Other comprehensive income — — — — 979 979 Dividends declared: — Common stock — — — — — — Preferred stock — — — — — — Balance at September 30, 2019 46,479,536 $ 46,479 $ 979,273 $ 526,800 $ (5,568) $ 1,546,984 Nine Months Ended September 30, 2020 Balance at December 31, 2019 46,479,536 $ 46,479 $ 979,273 $ 548,264 $ 4,576 1,578,592 Net income — — — 76,538 — 76,538 Other comprehensive income — — — — 2,745 2,745 Capital contribution from parent — — 175,000 — — 175,000 ASU 2016-13 implementation (a) — — — (1,543) — (1,543) Dividends declared: Common stock — — — (75,000) — (75,000) Balance at September 30, 2020 46,479,536 $ 46,479 $ 1,154,273 $ 548,259 $ 7,321 $ 1,756,332 Nine Months Ended September 30, 2019 Balance at December 31, 2018 46,479,536 $ 46,479 $ 979,273 $ 552,884 $ (7,106) $ 1,571,530 Net income — — — 24,576 — 24,576 Other comprehensive income — — — — 1,538 1,538 Dividends declared: Common stock — — — (50,000) — (50,000) Preferred stock — — — (660) — (660) Balance at September 30, 2019 46,479,536 $ 46,479 $ 979,273 $ 526,800 $ (5,568) $ 1,546,984 (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 market-related value of assets 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)	9 Months Ended
	Sep. 30, 2020
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) Three Months Ended September 30, 2020 2019 (c) (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 3.1 $ 1.3 $ 3.0 $ 1.3 Interest cost 8.9 2.3 10.2 3.0 Expected return on plan assets (10.6) (5.9) (10.5) (6.1) Recognized prior service cost (credit) 0.1 (3.4) 0.1 (3.9) Recognized actuarial loss (gain) 1.8 (0.5) 1.9 — Settlement charge 2.4 — — — Net periodic benefit cost (income) 5.7 (6.2) 4.7 (5.7) Allocation to affiliates (0.4) 0.5 (0.4) 0.5 Adjusted net periodic benefit cost (income) 5.3 (5.7) 4.3 (5.2) Amount allocated to construction projects (0.5) (0.2) (0.4) (0.2) Amount charged (credited) to expense $ 4.8 $ (5.9) $ 3.9 $ (5.4) Nine Months Ended September 30, 2020 2019 (c) (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 9.4 $ 4.0 $ 9.1 $ 3.8 Interest cost 26.6 6.9 30.7 9.0 Expected return on plan assets (31.9) (17.7) (31.4) (18.2) Recognized prior service cost (credit) 0.2 (10.2) 0.3 (11.7) Recognized actuarial loss (gain) 5.7 (1.5) 5.9 — Settlement charge (a) 3.6 — 4.3 — Net periodic benefit cost (income) 13.6 (18.5) 18.9 (17.1) Allocation to affiliates (1.2) 1.6 (1.3) 1.8 Adjusted net periodic benefit cost (income) 12.4 (16.9) 17.6 (15.3) Amount allocated to construction projects (1.6) (0.7) (1.2) (0.6) Amount deferred as regulatory asset (liability)-net allocations (b) — — 0.7 — Amount charged (credited) to expense $ 10.8 $ (17.6) $ 17.1 $ (15.9) (a) Amounts relate to partial settlement charges associated with lump sum payments from the Washington Gas’ defined benefit supplemental executive retirement plan (DB SERP). (b) Amount represents the amortization of previously unrecovered costs of the applicable pension benefits or the health and life benefits as approved in the District of Columbia through 2019. (c) In the third quarter of 2020, Washington Gas made a voluntary change in accounting principle for calculating the market-related value of assets 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.

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Absolute Notional Amounts of Open Positions on Derivative Instruments	The following table presents notional amounts of our outstanding derivatives September 30, 2020 and December 31, 2019. Absolute Notional Amounts of Open Positions on Derivative Instruments September 30, 2020 December 31, 2019 Natural Gas (In millions of therms) Asset optimization & trading 10,726.0 11,671.0 Other risk-management activities 915.0 976.0
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 September 30, 2020 Derivative assets (a) $ 20.2 $ (6.4) $ — $ 13.8 Derivative liabilities (b) (92.4) 6.4 — $ (86.0) Net derivative assets (liabilities) $ (72.2) $ — $ — $ (72.2) December 31, 2019 Derivative assets (a) $ 13.0 $ 4.0 $ — $ 17.0 Derivative liabilities (b) (104.0) (4.0) 6.2 (101.8) Net derivative assets (liabilities) $ (91.0) $ — $ 6.2 $ (84.8) (a) Derivative assets at September 30, 2020 include $4.7 million recorded in "Current assets — Derivatives" and $9.1 million in" Deferred charges and other assets — Derivatives" on Washington Gas' balance sheets; Derivative assets at December 31, 2019 include $6.6 million recorded in "Current assets —Derivatives" and $10.4 million in" Deferred charges and other assets — Derivatives" on Washington Gas' balance sheets. (b) Derivative liabilities at September 30, 2020 include $9.6 million recorded in "Current liabilities — Derivatives " and $76.4 million recorded in " Deferred credits — Derivatives" on Washington Gas' balance sheets; Derivative liabilities at December 31, 2019 include $4.1 million recorded in "Current liabilities — Derivatives " and $97.7 million recorded in " Deferred credits — Derivatives" on Washington Gas' balance sheets.
Gains and (Losses) on Derivative Instruments	The following tables present all gains and losses associated with derivative instruments for the three and nine months ended September 30, 2020 and 2019. Gains and (Losses) on Derivative Instruments (In millions) Three Months Ended Nine Months Ended 2020 2019 2020 2019 Recorded to income-Utility cost of gas $ (0.3) $ (5.8) $ 6.2 $ (0.1) Recorded to regulatory assets-Gas costs (7.1) (9.6) 9.8 4.8 Total $ (7.4) $ (15.4) $ 16.0 $ 4.7
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 September 30, 2020 and December 31, 2019, respectively. Potential Collateral Requirements for Derivative Liabilities (In millions) September 30, 2020 December 31, 2019 Derivative liabilities with credit-risk-contingent features $ 0.2 $ 0.4 Maximum potential collateral requirements $ 0.2 $ 0.4

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
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. (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At September 30, 2020 Financial assets Fair value through net income Cash equivalents (a) $ 0.8 $ 0.8 $ — $ — $ 0.8 Rabbi trust investments (b) 28.0 28.0 — — 28.0 Derivative asset - current 1.9 — 0.2 1.7 1.9 Derivative asset - deferred 3.7 — — 3.7 3.7 Fair value through regulatory assets/liabilities Derivative asset - current 2.8 — 0.4 2.4 2.8 Derivative asset - deferred 5.4 — — 5.4 5.4 Amortized cost Other long-term receivables (c) 1.3 — 1.3 — 1.3 Total Assets $ 43.9 $ 28.8 $ 1.9 $ 13.2 $ 43.9 Financial Liabilities Fair value through net income Derivative liabilities - current $ (2.4) $ — $ (0.2) $ (2.2) $ (2.4) Derivative liabilities - deferred (22.8) — — (22.8) (22.8) Fair value through regulatory assets/liabilities Derivative liabilities - current (7.2) — (0.4) (6.8) (7.2) Derivative liabilities - deferred (53.6) — — (53.6) (53.6) Amortized cost Commercial paper (d) (270.0) — (270.0) — (270.0) Unsecured notes (e) (1,331.4) — (1,605.0) — (1,605.0) Total Liabilities $ (1,687.4) $ — $ (1,875.6) $ (85.4) $ (1,961.0) (In millions) Carrying Amount Level 1 Level 2 Level 3 Total At December 31, 2019 Financial assets Fair value through net income Cash equivalents (a) $ 11.0 $ 11.0 $ — $ — $ 11.0 Rabbi trust investments (b) 44.1 44.1 — — 44.1 Derivative asset - current 2.6 — 0.1 2.5 2.6 Derivative asset - deferred 4.1 — 0.2 3.9 4.1 Fair value through regulatory assets/liabilities Derivative asset - current 4.0 — — 4.0 4.0 Derivative asset - deferred 6.3 — 0.3 6.0 6.3 Amortized cost Other long-term receivables (c) 1.3 — 1.3 — 1.3 Total Assets $ 73.4 $ 55.1 $ 1.9 $ 16.4 $ 73.4 Financial Liabilities Fair value through net income Derivative liabilities - current $ (0.7) $ — $ — $ (0.7) (0.7) Derivative liabilities - deferred (28.4) — — (28.4) (28.4) Fair value through regulatory assets/liabilities Derivative liabilities - current (3.4) — (0.6) (2.8) (3.4) Derivative liabilities - deferred (69.3) — — (69.3) (69.3) Amortized cost Commercial paper (d) (399.5) — (399.5) — (399.5) Unsecured notes (e) (1,330.9) — (1,480.8) — (1,480.8) Total Liabilities $ (1,832.2) $ — $ (1,880.9) $ (101.2) $ (1,982.1) (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 September 30, 2020, carrying amount of $7.5 million and $20.5 million was included in "Current assets — Other" and "Deferred charges and other assets — Other" of the accompanying balance sheets, respectively; At December 31, 2019, carrying amount of $19.5 million and $24.6 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 discussed in Note 11 — Commitments and Contingencies. The carrying amount represents the long-term receivable net of allowance for doubtful accounts. (d) The balance at September 30, 2020 includes $170.0 million located in "Notes payable", and $100.0 million located in “Long-term debt” on the accompanying balance sheets. The balance at December 31, 2019 includes $299.5 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 (a) Range September 30, 2020 ($72.2) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($0.34) ($1.105)-$2.068 December 31, 2019 ($84.8) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) n/a ($0.905)-$2.523 (a) ASU 2018-13 has been applied prospectively, beginning with the interim period ending March 31, 2020. The average level 3 price was weighted by transaction volume.
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 Nine Months Ended (In millions) 2020 2019 2020 2019 Balance at beginning of period $ (65.8) $ (86.9) $ (84.8) $ (106.6) Realized and unrealized gains (losses) Recorded to income (0.2) (6.2) 5.2 (1.4) Recorded to regulatory assets — Gas costs (6.4) (10.1) 9.0 4.3 Transfers into Level 3 — (2.9) — (6.7) Transfers out of Level 3 — 2.9 — 7.9 Settlements 0.2 (3.1) (1.6) (3.8) Balance at end of period $ (72.2) $ (106.3) $ (72.2) $ (106.3)
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 Nine Months Ended (In millions) 2020 2019 2020 2019 Recorded to income — Utility cost of gas $ 0.2 $ (5.9) $ 8.6 $ 1.6 Recorded to regulatory assets — Gas costs (4.4) (10.2) 14.5 7.9 Total $ (4.2) $ (16.1) $ 23.1 $ 9.5

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Gas Balancing Service Charges	The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Washington Gas - Gas Balancing Service Charges Three Months Ended Nine Months Ended (In millions) 2020 2019 2020 2019 Gas balancing service charge $ 2.7 $ 2.9 $ 12.4 $ 14.9

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table shows the changes in accumulated other comprehensive income (loss) (AOCI) by component for the reporting periods. Changes in Accumulated Other Comprehensive Income (Loss) by Component Three Months Ended Nine Months Ended (In thousands) 2020 2019 (c) 2020 2019 (c) Beginning Balance $ 6,266 $ (6,547) $ 4,576 $ (7,106) Amortization of prior service credit (a)(b) (292) (163) (924) (486) Amortization of actuarial loss (a)(b) 427 442 1,432 1,346 Actuarial gain (loss) arising during the period (a) 1,286 — 3,196 1,250 Current-period other comprehensive income 1,421 279 3,704 2,110 Income tax expense related to pension and other post-retirement benefit plans retained in AOCI 366 (700) 959 572 Ending Balance $ 7,321 $ (5,568) $ 7,321 $ (5,568) (a) The accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. (b) Amortization of prior service cost and amortization of actuarial gain (loss) represent the amounts reclassified out of AOCI to “Other income (expense)” 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 market-related value of assets 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)	9 Months Ended
	Sep. 30, 2020
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. Nine Months Ended September 30, (In thousands) 2020 2019 CHANGES IN OPERATING ASSETS AND LIABILITIES Receivables $ 177,598 $ 174,986 (Receivables from) Payables to associated companies — net 8,754 6,402 Gas costs and other regulatory assets/liabilities — net (82,387) (8,253) Storage gas 15,900 11,479 Prepaid taxes 4,097 (3,791) Accounts payable and other accrued liabilities (67,114) (109,287) Customer deposits and advance payments (1,785) (11,511) Accrued taxes 4,500 6,830 Other current assets 20,226 5,077 Other current liabilities 4,163 (240) Deferred gas costs — net 16,360 49,379 Deferred assets — other (19,523) 11,807 Deferred liabilities — other (14,929) (26,879) Pension and other post-retirement benefits (12,152) (11,427) Changes in operating assets and liabilities $ 53,708 $ 94,572 SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION Income taxes paid (refunded) — net (2,880) 5,253 Interest paid 62,169 54,238 SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES: Extinguishment of project debt financing activities — net — (15,460) Capital expenditure accruals included in accounts payable and other accrued liabilities $ 52,643 $ 39,976
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) September 30, 2020 September 30, 2019 Cash and cash equivalents $ 1,214 $ 1 Restricted cash included in Current assets-Other 7,507 4,225 Restricted cash included in Deferred charges and other assets-Other 20,519 43,945 Total cash, cash equivalents and restricted cash shown in the statements of cash flows $ 29,240 $ 48,171

Accounting Policies - (Details)

Accounting Policies - (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended	15 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2019	Jun. 30, 2020	Jan. 01, 2020	Sep. 30, 2019	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 548,259	$ 548,259	$ 548,264	$ 548,264
Accumulated other comprehensive income (loss)	7,321	7,321	4,576	4,576
Common shareholder’s equity	1,756,332	1,756,332	1,578,592	1,578,592	$ 1,766,899		$ 1,546,984	$ 1,612,481		$ 1,571,530
Allowance for credit losses	$ 26,517	$ 26,517	$ 18,708	$ 18,708
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Revision of Prior Period, Change in Accounting Principle, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 11,754	$ 11,754	$ 6,729	$ 6,729					$ 9,400
Accumulated other comprehensive income (loss)	(856)	(856)	(333)	(333)					400
Common shareholder’s equity	$ 10,898	$ 10,898	6,396	6,396					$ 9,000
Cumulative effect of adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Common shareholder’s equity			$ (1,543)	$ (1,543)
Allowance for credit losses						$ 1,500

Accounting Policies - Change in

Accounting Policies - Change in Accounting Policy (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Pension and other post retirement benefits	$ 39,966		$ 39,966			$ 44,078
Common shareholder’s equity	1,756,332	$ 1,546,984	1,756,332	$ 1,546,984	$ 1,766,899	1,578,592	$ 1,612,481		$ 1,571,530
Regulatory liabilities — Other post-retirement benefits	184,370		184,370			195,670
Deferred income taxes	518,208		518,208			464,717
Retained earnings	548,259		548,259			548,264
Accumulated other comprehensive income (loss), net of taxes	7,321		7,321			4,576
Other Nonoperating Income (Expense)	4,070	2,619	16,419	4,556
Income tax expense (benefit)	(11,324)	(19,530)	15,477	4,280
Net income (loss)	(36,622)	(66,476)	76,538	24,576
Other comprehensive income (loss), net of tax	1,055	979	2,745	1,538
Comprehensive income (loss)	(35,567)	(65,497)	79,283	26,114
Accrued/deferred pension and other post-retirement benefit cost (benefit)			(6,758)	1,793
Deferred income taxes — net			15,908	6,375
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Pension and other post retirement benefits	31,337		31,337			39,435
Common shareholder’s equity	1,745,434		1,745,434			1,572,196
Regulatory liabilities — Other post-retirement benefits	190,460		190,460			199,665
Deferred income taxes	514,387		514,387			462,475
Retained earnings	536,505		536,505			541,535
Accumulated other comprehensive income (loss), net of taxes	8,177		8,177			4,909
Other Nonoperating Income (Expense)	1,808	3,533	9,632	7,298
Income tax expense (benefit)	(11,911)	(19,293)	13,715	4,992
Net income (loss)	(38,297)	(65,799)	71,513	26,606
Other comprehensive income (loss), net of tax	1,229	942	3,268	1,428
Comprehensive income (loss)	(37,068)	(64,857)	74,781	28,034
Accrued/deferred pension and other post-retirement benefit cost (benefit)			29	(949)
Deferred income taxes — net			14,146	7,087
Revision of Prior Period, Change in Accounting Principle, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Pension and other post retirement benefits	8,629		8,629			4,643
Common shareholder’s equity	10,898		10,898			6,396		$ 9,000
Regulatory liabilities — Other post-retirement benefits	(6,090)		(6,090)			(3,995)
Deferred income taxes	3,821		3,821			2,242
Retained earnings	11,754		11,754			6,729		9,400
Accumulated other comprehensive income (loss), net of taxes	(856)		(856)			$ (333)		$ 400
Other Nonoperating Income (Expense)	2,262	(914)	6,787	(2,742)
Income tax expense (benefit)	587	(237)	1,762	(712)
Net income (loss)	1,675	(677)	5,025	(2,030)
Other comprehensive income (loss), net of tax	(174)	37	(523)	110
Comprehensive income (loss)	$ 1,501	$ (640)	4,502	(1,920)
Accrued/deferred pension and other post-retirement benefit cost (benefit)			(6,787)	2,742
Deferred income taxes — net			$ 1,762	$ (712)

Credit Losses - Narrative (Deta

Credit Losses - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended	15 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2019	Jun. 30, 2020	Jan. 01, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Allowance for credit losses	$ 26,517	$ 26,517	$ 18,708	$ 18,708
Long term receivable from trading partner	$ 26,500	$ 26,500	18,700	18,700	$ 23,200
Cumulative effect of adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses						$ 1,500
Credit loss reserve for long term trading receivable						(100)
Long term receivable from trading partner			$ 1,400	$ 1,400	$ 0	$ 1,400

Credit Losses - Rollforward of

Credit Losses - Rollforward of Allowance Accounts (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended	15 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2019
Account Receivables and Unbilled Revenue
Balance, beginning of period	$ 23,200	$ 18,700
Provision	1,300	11,101	$ 10,615
Recorded to regulatory asset due to COVID-19	4,700	7,700
Write offs	(3,000)	(13,800)
Recoveries	300	1,400
Balance, end of period	$ 26,500	$ 26,500		$ 18,700	$ 18,700
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Cumulative effect of adoption
Account Receivables and Unbilled Revenue
Balance, beginning of period	$ 0	$ 1,400
Balance, end of period				$ 1,400	$ 1,400
Asset Optimization
Account Receivables and Unbilled Revenue
Balance, beginning of period	100	0
Provision	0	0
Write offs	0	0
Recoveries	0	0
Balance, end of period	100	100		0	0
Asset Optimization | Cumulative effect of adoption
Account Receivables and Unbilled Revenue
Balance, beginning of period	$ 0	$ 100
Balance, end of period				$ 100	$ 100

Revenue from Contracts With C_3

Revenue from Contracts With Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 135,600	$ 116,400	$ 805,000	$ 890,500
Revenue from alternative revenue programs	7,600	3,600	47,700	14,900
Leasing revenue	200	200	500	500
Other	0	2,100	3,100	8,500
Other sources of revenue	7,800	5,900	51,300	23,900
Total Operating Revenue	143,383	122,305	856,284	914,442
Gas and transportation sales | Gas sold and delivered
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	91,200	70,700	592,800	665,100
Gas and transportation sales | Gas delivered for others
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	39,500	33,400	186,500	186,800
Gas and transportation sales | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,600	10,900	23,600	34,400
Other revenues
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,300	$ 1,400	$ 2,100	$ 4,200

Revenue From Contracts With C_4

Revenue From Contracts With Customers - Contract Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Unbilled revenues	$ 28.5		$ 116.3
Contract assets at January 1	44.2	$ 85.3
Contract assets at September 30	51.8	40.5
Increase (decrease) in contract assets	$ 7.6	$ (44.8)

Accounts Payable and Other Ac_3

Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Accounts Payable and Accrued Liabilities [Abstract]
Accounts payable—trade	$ 135.3	$ 154.3
Employee benefits and payroll accruals	20.9	39.3
Wages payable	25.6	22.2
Accrued interest	3.2	17.3
Other accrued liabilities	32	34.4
Total	217	267.5
Antero contract
Loss Contingencies [Line Items]
Loss contingency accrual	$ 12.3	$ 11.7

Short-Term Debt - Commitment Cr

Short-Term Debt - Commitment Credit Available (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Less: Commercial Paper outstanding	$ (270,000,000)	$ (399,500,000)
Credit facility
Short-term Debt [Line Items]
Unsecured revolving credit facility	450,000,000	450,000,000
Less: Commercial Paper outstanding	(270,000,000)	(400,000,000)
Net committed credit available	$ 180,000,000	$ 50,000,000
Weighted average interest rate	0.27%	2.04%
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 ($)	Sep. 30, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Commercial paper	$ 270,000,000	$ 399,500,000
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	170,000,000	299,500,000
Credit facility
Short-term Debt [Line Items]
Outstanding bank loans	0	0
Commercial paper	$ 270,000,000	$ 400,000,000

Long Term Debt (Details)

Long Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Long Term Debt [LIne Items]
Long-term debt	$ 1,446,000	$ 1,446,000
Unamortized discount	(4,200)	(4,300)
Unamortized debt expense	(10,400)	(10,800)
Less—current maturities	0	0
Total Long-Term Debt	$ 1,431,390	$ 1,430,949
Weighted average interest rate	4.52%	4.52%
Unsecured Notes
Long Term Debt [LIne Items]
Long-term debt	$ 1,346,000	$ 1,346,000
Commercial Paper
Long Term Debt [LIne Items]
Long-term debt	$ 100,000	$ 100,000

Long-Term Debt (Schedule of Deb

Long-Term Debt (Schedule of Debt Issuance) (Details)	Sep. 13, 2019USD ($)
Debt Disclosure [Abstract]
Principal	$ 300,000,000
Interest rate	3.65%
Effective cost	3.72%

Components of Total Equity - (D

Components of Total Equity - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended	15 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,766,899	$ 1,612,481	$ 1,578,592	$ 1,571,530	$ 1,571,530
NET INCOME (LOSS)	(36,622)	(66,476)	76,538	24,576
Other comprehensive income	1,055	979	2,745	1,538
Capital contribution from parent	50,000		175,000
Dividends Abstract
Common Stock	(25,000)	0	(75,000)	(50,000)
Preferred Stock		0		(660)
Ending Balance	$ 1,756,332	$ 1,546,984	$ 1,756,332	$ 1,546,984	$ 1,578,592	$ 1,578,592
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Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	46,479,536	46,479,536	46,479,536	46,479,536	46,479,536
Beginning Balance	$ 46,479	$ 46,479	$ 46,479	$ 46,479	$ 46,479
Dividends Abstract
Ending Balance (in shares)	46,479,536	46,479,536	46,479,536	46,479,536	46,479,536	46,479,536
Ending Balance	$ 46,479	$ 46,479	$ 46,479	$ 46,479	$ 46,479	$ 46,479
Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,104,273	979,273	979,273	979,273	979,273
Capital contribution from parent	50,000		175,000
Dividends Abstract
Ending Balance	1,154,273	979,273	1,154,273	979,273	979,273	979,273
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	609,881	593,276	548,264	552,884	552,884
NET INCOME (LOSS)	(36,622)	(66,476)	76,538	24,576
Dividends Abstract
Common Stock	(25,000)		(75,000)	(50,000)
Preferred Stock				(660)
Ending Balance	548,259	526,800	548,259	526,800	548,264	548,264
Accumulated Other Comprehensive Income/(Loss), Net of Taxes
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	6,266	(6,547)	4,576	(7,106)	(7,106)
Other comprehensive income	1,055	979	2,745	1,538
Dividends Abstract
Ending Balance	$ 7,321	$ (5,568)	7,321	$ (5,568)	4,576	4,576
Cumulative effect of adoption
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(1,543)
Dividends Abstract
Ending Balance					(1,543)	(1,543)
Cumulative effect of adoption | Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ (1,543)
Dividends Abstract
Ending Balance					$ (1,543)	$ (1,543)

Income Taxes - (Details)

Income Taxes - (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Receivables from associated companies	$ 5.5	$ 5.5
Payables to associated companies	$ 0.6	$ 0.6

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		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3.1	$ 3	$ 9.4	$ 9.1
Interest cost	8.9	10.2	26.6	30.7
Expected return on plan assets	(10.6)	(10.5)	(31.9)	(31.4)
Recognized prior service cost (credit)	0.1	0.1	0.2	0.3
Recognized actuarial loss (gain)	1.8	1.9	5.7	5.9
Settlement charge	2.4	0	3.6	4.3
Net periodic benefit cost (income)	5.7	4.7	13.6	18.9
Allocation to affiliates	(0.4)	(0.4)	(1.2)	(1.3)
Adjusted net periodic benefit cost (income)	5.3	4.3	12.4	17.6
Amount allocated to construction projects	(0.5)	(0.4)	(1.6)	(1.2)
Amount deferred as regulatory asset (liability)-net allocations			0	0.7
Amount charged (credited) to expense	4.8	3.9	10.8	17.1
Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.3	1.3	4	3.8
Interest cost	2.3	3	6.9	9
Expected return on plan assets	(5.9)	(6.1)	(17.7)	(18.2)
Recognized prior service cost (credit)	(3.4)	(3.9)	(10.2)	(11.7)
Recognized actuarial loss (gain)	(0.5)	0	(1.5)	0
Settlement charge	0	0	0	0
Net periodic benefit cost (income)	(6.2)	(5.7)	(18.5)	(17.1)
Allocation to affiliates	0.5	0.5	1.6	1.8
Adjusted net periodic benefit cost (income)	(5.7)	(5.2)	(16.9)	(15.3)
Amount allocated to construction projects	(0.2)	(0.2)	(0.7)	(0.6)
Amount deferred as regulatory asset (liability)-net allocations			0	0
Amount charged (credited) to expense	$ (5.9)	$ (5.4)	$ (17.6)	$ (15.9)

Pension and Other Post-Retire_4

Pension and Other Post-Retirement Benefit Plans - Narrative (Details) - Rabbi Trusts - DB SERP - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan assets	$ 24.8	$ 40
Other assets, current
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan assets	7.5	19.5
Other noncurrent assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan assets	$ 17.3	$ 20.5

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Commitments and Contingencies [Line Items]
Operation and maintenance expenses		$ 94,175,000	$ 101,195,000	$ 291,885,000	$ 300,433,000
Deferred gas cost		69,076,000		69,076,000		$ 98,717,000
Accrued minimum liability expected amount		330,000		330,000
Statutory amount available for dividend payments with regulatory approval		25,000		25,000
Derivative asset - deferred		99,267,000		99,267,000		84,886,000
Environmental response costs
Commitments and Contingencies [Line Items]
Derivative asset - deferred		6,800,000		6,800,000		7,000,000
Environmental response costs | Reserve for Environmental Costs
Commitments and Contingencies [Line Items]
Accrual for environmental loss contingencies		10,400,000		10,400,000		10,700,000
Estimated maximum liability				30,700,000		30,700,000
Antero contract
Commitments and Contingencies [Line Items]
Loss contingency, damages awarded, value	$ 95,900,000
Loss contingency accrual		12,300,000		12,300,000		$ 11,700,000
Antero contract | Washington gas
Commitments and Contingencies [Line Items]
Loss contingency, damages awarded, value	11,200,000
Loss contingency accrual		12,300,000		12,300,000
Loss contingency, receivable		1,300,000		1,300,000
Deferred gas cost		5,000,000		5,000,000
Net pre tax loss					$ 3,000,000
Antero contract | WGL midstream
Commitments and Contingencies [Line Items]
Loss contingency, damages awarded, value	$ 84,700,000
Minimum | Virginia
Commitments and Contingencies [Line Items]
Estimate of possible loss		620,500		620,500
Maximum | Virginia
Commitments and Contingencies [Line Items]
Estimate of possible loss		123,300,000		123,300,000
Merger agreement, circumstance 2
Commitments and Contingencies [Line Items]
Other commitments payable		$ 15,900,000		15,900,000
Merger agreement, circumstance 2 | Future hiring
Commitments and Contingencies [Line Items]
Operation and maintenance expenses				$ 2,400,000
Regulatory commitments, term				5 years
Merger agreement, circumstance 2 | Extend natural gas service
Commitments and Contingencies [Line Items]
Operation and maintenance expenses				$ 70,000,000
Regulatory commitments, term				10 years
Merger agreement, circumstance 2 | Future leak mitigation
Commitments and Contingencies [Line Items]
Operation and maintenance expenses				$ 8,000,000
Regulatory commitments, term				3 years

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)counterparty	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)counterparty	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Collaborative arrangement expenses	$ 2.4	$ 2.5	$ 5.8	$ 3.8
Gain (loss) on asset optimization transactions net pretax	5.1	(1.2)	19.7	8.3
Unrealized gains (loss) on asset optimization derivative instruments net pretax	(1.3)	$ (6.5)	5.5	0.1
Asset optimization loss contingency related				$ 3
Right to reclaim cash	1		1		$ 5.2
Derivative, collateral, obligation to return cash	$ 0.1		$ 0.1		$ 0.1
Number of counterparties | counterparty	1		1
Percentage of credit exposure	10.00%		10.00%
Concentration risk credit risk financial instrument exposure	$ 15.1		$ 15.1

Derivatives - Open Positions on

Derivatives - Open Positions on Derivative Instruments (Details) - BTU BTU in Millions	Sep. 30, 2020	Dec. 31, 2019
Asset optimization & trading
Derivative [Line Items]
Natural gas derivative transaction, volume	10,726	11,671
Other risk-management activities
Derivative [Line Items]
Natural gas derivative transaction, volume	915	976

Derivatives - Balance Sheet Cla

Derivatives - Balance Sheet Classification of Derivative Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross amounts of recognized assets/(liabilities)	$ 20.2	$ 13
Gross amounts offset in balance sheet	(6.4)	4
Netting of collateral	0	0
Net amounts presented on balance sheet	13.8	17
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Gross amounts of recognized assets/(liabilities)	(92.4)	(104)
Gross amounts offset in balance sheet	6.4	(4)
Netting of collateral	0	6.2
Net amounts presented on balance sheet	(86)	(101.8)
Total, gross amounts of recognized assets/(liabilities)	(72.2)	(91)
Total, gross amounts offset in balance sheet	0	0
Total, netting of collateral	0	6.2
Total	(72.2)	(84.8)
Current assets—Derivatives
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	4.7	6.6
Deferred charges and other assets—Derivatives
Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	9.1	10.4
Current liabilities—Derivatives
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	(9.6)	(4.1)
Deferred credits—Derivatives
Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract]
Net amounts presented on balance sheet	$ (76.4)	$ (97.7)

Derivatives - Gains and Losses

Derivatives - Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Gains and (Losses) on Derivative Instruments
Total	$ (7.4)	$ (15.4)	$ 16	$ 4.7
Recorded to income-Utility cost of gas
Gains and (Losses) on Derivative Instruments
Recorded to income	(0.3)	(5.8)	6.2	(0.1)
Recorded to regulatory assets-Gas costs
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets	$ (7.1)	$ (9.6)	$ 9.8	$ 4.8

Derivatives - Credit Risk Conti

Derivatives - Credit Risk Contingent Features (Details) - Credit Risk Contract - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative liabilities with credit-risk-contingent features	$ 0.2	$ 0.4
Maximum potential collateral requirements	$ 0.2	$ 0.4

Fair Value Measurements - Under

Fair Value Measurements - Under the Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Financial assets
Cash equivalents	$ 800	$ 11,000
Rabbi trust investments	28,000	44,100
Derivative asset - current	4,665	6,553
Derivative asset - deferred	9,113	10,370
Other long-term receivables	1,300	1,300
Total Assets	43,900	73,400
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(9,622)	(4,069)
Fair value through net income, Derivative liabilities - deferred	(76,407)	(97,695)
Commercial paper	(270,000)	(399,500)
Unsecured Debt	(1,605,000)	(1,480,800)
Total Liabilities	(1,961,000)	(1,982,100)
Restricted cash included in Current assets-Other	7,507		$ 4,225
Long-term debt	1,446,000	1,446,000
Commercial Paper
Financial Liabilities
Long-term debt		100,000
Level 1
Financial assets
Cash equivalents	800	11,000
Rabbi trust investments	28,000	44,100
Other long-term receivables	0	0
Total Assets	28,800	55,100
Financial Liabilities
Commercial paper	0	0
Unsecured Debt	0	0
Total Liabilities	0	0
Level 2
Financial assets
Cash equivalents	0	0
Rabbi trust investments	0	0
Other long-term receivables	1,300	1,300
Total Assets	1,900	1,900
Financial Liabilities
Commercial paper	(270,000)	(399,500)
Unsecured Debt	(1,605,000)	(1,480,800)
Total Liabilities	(1,875,600)	(1,880,900)
Level 3
Financial assets
Cash equivalents	0	0
Rabbi trust investments	0	0
Other long-term receivables	0	0
Total Assets	13,200	16,400
Financial Liabilities
Commercial paper	0	0
Unsecured Debt	0	0
Total Liabilities	(85,400)	(101,200)
Carrying Amount
Financial assets
Cash equivalents		11,000
Rabbi trust investments		44,100
Other long-term receivables	1,300	1,300
Total Assets	43,900	73,400
Financial Liabilities
Commercial paper	(270,000)	(399,500)
Unsecured Debt	(1,331,400)	(1,330,900)
Total Liabilities	(1,687,400)	(1,832,200)
Derivative assets
Financial assets
Derivative asset - current	1,900	2,600
Derivative asset - deferred	3,700	4,100
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	200	100
Derivative asset - deferred	0	200
Derivative assets | Level 3
Financial assets
Derivative asset - current	1,700	2,500
Derivative asset - deferred	3,700	3,900
Derivative assets | Carrying Amount
Financial assets
Derivative asset - current	1,900	2,600
Derivative asset - deferred	3,700	4,100
Regulatory assets
Financial assets
Derivative asset - current	2,800	4,000
Derivative asset - deferred	5,400	6,300
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	400	0
Derivative asset - deferred	0	300
Regulatory assets | Level 3
Financial assets
Derivative asset - current	2,400	4,000
Derivative asset - deferred	5,400	6,000
Regulatory assets | Carrying Amount
Financial assets
Derivative asset - current	2,800	4,000
Derivative asset - deferred	5,400	6,300
Derivative liabilities
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(2,400)	(700)
Fair value through net income, Derivative liabilities - deferred	(22,800)	(28,400)
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	(200)	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	(2,200)	(700)
Fair value through net income, Derivative liabilities - deferred	(22,800)	(28,400)
Derivative liabilities | Carrying Amount
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(2,400)	(700)
Fair value through net income, Derivative liabilities - deferred	(22,800)	(28,400)
Regulatory liabilities
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(7,200)
Fair value through net income, Derivative liabilities - deferred	(53,600)
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(3,400)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(69,300)
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	(400)
Fair value through net income, Derivative liabilities - deferred	0
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(600)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		0
Regulatory liabilities | Level 3
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(6,800)
Fair value through net income, Derivative liabilities - deferred	(53,600)
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(2,800)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(69,300)
Regulatory liabilities | Carrying Amount
Financial Liabilities
Fair value through net income, Derivative liabilities - current	(7,200)
Fair value through net income, Derivative liabilities - deferred	(53,600)
Fair value through regulatory assets/liabilities, Derivative liabilities - current		(3,400)
Fair value through regulatory assets/liabilities, Derivative liabilities - deferred		(69,300)
Other assets, current
Financial Liabilities
Restricted cash included in Current assets-Other	7,500	19,500
Note payable and project financing
Financial Liabilities
Commercial paper	$ (170,000)	$ (299,500)

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative information (Details) - Natural Gas Related Derivatives $ in Millions	Sep. 30, 2020USD ($)$ / dekatherm	Jun. 30, 2020USD ($)	Dec. 31, 2019USD ($)$ / dekatherm	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value Measurements Details [Line Items]
Net Fair Value | $	$ (72.2)	$ (65.8)	$ (84.8)	$ (106.3)	$ (86.9)	$ (106.6)
Discounted Cash Flow
Fair Value Measurements Details [Line Items]
Net Fair Value | $	$ (72.2)		$ (84.8)
Discounted Cash Flow | Weighted Average | Natural Gas Basis Price
Fair Value Measurements Details [Line Items]
Input price	(0.34)
Discounted Cash Flow | Maximum | Natural Gas Basis Price
Fair Value Measurements Details [Line Items]
Input price	2.068		2.523
Discounted Cash Flow | Minimum | Natural Gas Basis Price
Fair Value Measurements Details [Line Items]
Input price	(1.105)		(0.905)

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation with Level 3 Inputs (Details) - Natural Gas Related Derivatives - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs
Beginning of period	$ (65.8)	$ (86.9)	$ (84.8)	$ (106.6)
Recorded to income	(0.2)	(6.2)	5.2	(1.4)
Recorded to regulatory assets — Gas costs	(6.4)	(10.1)	9	4.3
Transfers into Level 3	0	(2.9)	0	(6.7)
Transfers out of Level 3	0	2.9	0	7.9
Settlements	0.2	(3.1)	(1.6)	(3.8)
End of period	$ (72.2)	$ (106.3)	$ (72.2)	$ (106.3)

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		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets	$ (6.4)	$ (10.1)	$ 9	$ 4.3
Total	(4.2)	(16.1)	23.1	9.5
Recorded to income-Utility cost of gas
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	0.2	(5.9)	8.6	1.6
Regulatory asset-gas costs member
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets	$ (4.4)	$ (10.2)	$ 14.5	$ 7.9

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted cash, current	$ 7,507		$ 4,225
Restricted cash, noncurrent	20,519		$ 43,945
Commercial paper	270,000	$ 399,500
Long-term debt	1,446,000	1,446,000
Other assets, current
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted cash, current	7,500	19,500
Deferred charges and other assets—Derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted cash, noncurrent	20,500	24,600
Note payable and project financing
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial paper	$ 170,000	299,500
Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt		100,000
Notes payable		$ 299,500

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Operation and maintenance		$ 94,175	$ 101,195	$ 291,885	$ 300,433
Contract asset		51,800	40,500	51,800	40,500	$ 40,500	$ 44,200	$ 85,300
Payables to associated companies		63,176		63,176			57,923
WGL Energy Services
Related Party Transaction [Line Items]
Gas balancing service charge		2,700	2,900	12,400	14,900
Related party purchased receivables		2,900		2,900			7,900
Hampshire Gas Company
Related Party Transaction [Line Items]
Operation and maintenance		2,300	1,500	6,400		$ 5,500
WGL Energy Systems | Energy management services projects not complete
Related Party Transaction [Line Items]
Payables to associated companies		51,800		51,800			44,200	$ 53,000
Repayments of debt	$ 53,000
WGL Energy Services
Related Party Transaction [Line Items]
Payables to associated companies		200		200			$ 2,100
Shared service costs | Parent Company
Related Party Transaction [Line Items]
Operation and maintenance		$ 5,300	$ 5,000	$ 15,400	$ 12,500

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI, Net of Tax [Roll Forward]
Beginning Balance	$ 1,766,899	$ 1,612,481	$ 1,578,592	$ 1,571,530
Current-period other comprehensive income	1,421	279	3,704	2,110
Income tax expense related to pension and other post-retirement benefit plans retained in AOCI	366	(700)	959	572
Ending Balance	1,756,332	1,546,984	1,756,332	1,546,984
Accumulated other comprehensive income (loss)
AOCI, Net of Tax [Roll Forward]
Beginning Balance	6,266	(6,547)	4,576	(7,106)
Ending Balance	7,321	(5,568)	7,321	(5,568)
Amortization of prior service cost
AOCI, Net of Tax [Roll Forward]
Reclassification	(292)	(163)	(924)	(486)
Amortization of actuarial gain (loss)
AOCI, Net of Tax [Roll Forward]
Reclassification	427	442	1,432	1,346
Actuarial gain (loss) arising during the period	$ 1,286	$ 0	$ 3,196	$ 1,250

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
CHANGES IN OPERATING ASSETS AND LIABILITIES
Receivables	$ 177,598	$ 174,986
(Receivables from) Payables to associated companies — net	8,754	6,402
Gas costs and other regulatory assets/liabilities — net	(82,387)	(8,253)
Storage gas	15,900	11,479
Prepaid taxes	4,097	(3,791)
Accounts payable and other accrued liabilities	(67,114)	(109,287)
Customer deposits and advance payments	(1,785)	(11,511)
Accrued taxes	4,500	6,830
Other current assets	20,226	5,077
Other current liabilities	4,163	(240)
Deferred gas costs — net	16,360	49,379
Deferred assets — other	(19,523)	11,807
Deferred liabilities — other	(14,929)	(26,879)
Pension and other post-retirement benefits	(12,152)	(11,427)
Changes in operating assets and liabilities	53,708	94,572
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid (refunded) — net	(2,880)	5,253
Interest paid	62,169	54,238
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Extinguishment of project debt financing activities — net	0	(15,460)
Capital expenditure accruals included in accounts payable and other accrued liabilities	52,643	39,976
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	1,214	1	$ 17,069
Restricted cash included in Current assets-Other	7,507	4,225
Restricted cash included in Deferred charges and other assets-Other	20,519	43,945
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 29,240	$ 48,171	$ 61,148	$ 71,423