WGL (WGL) 10-Q 4 Aug 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2016	Jul. 31, 2016
Document Information [Line Items]
Entity Registrant Name	WGL Holdings Inc.
Entity Central Index Key	1,103,601
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		51,059,773
Washington Gas Light Company
Document Information [Line Items]
Entity Registrant Name	Washington Gas Light Company
Entity Central Index Key	104,819
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		0

Balance Sheets (Unaudited)

Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Property, Plant and Equipment
At original cost	$ 5,335,684	$ 5,003,910
Accumulated depreciation and amortization	(1,385,486)	(1,331,182)
Net property, plant and equipment	3,950,198	3,672,728
Current Assets
Cash and cash equivalents	16,534	6,733
Receivables
Accounts receivable	310,094	276,358
Gas costs and other regulatory assets	17,106	5,797
Unbilled revenues	154,986	102,560
Allowance for doubtful accounts	(24,798)	(26,224)
Net receivables	457,388	358,491
Materials and supplies—principally at average cost	18,655	21,402
Storage gas	172,718	211,443
Prepaid taxes	63,388	48,726
Other prepayments	44,279	32,850
Derivatives	16,521	22,933
Assets held for sale	0	22,906
Other	31,071	23,057
Total current assets	820,554	748,541
Regulatory assets
Gas costs	153,075	190,676
Pension and other post-retirement benefits	194,282	212,041
Other	99,785	80,018
Prepaid post-retirement benefits	152,914	138,629
Derivatives	42,969	32,132
Investments in direct financing leases, capital leases	31,262	35,234
Investments in unconsolidated affiliates	282,780	136,884
Other	14,994	14,476
Total deferred charges and other assets	972,061	840,090
Total Assets	5,742,813	5,261,359
Capitalization
Common shareholders’ equity	1,411,081	1,243,247
Washington Gas Light Company preferred stock	28,173	28,173
Long-term debt	1,194,275	944,201
Total capitalization	2,633,529	2,215,621
Current Liabilities
Current maturities of long-term debt	0	25,000
Notes payable	358,342	332,000
Accounts payable and other accrued liabilities	333,160	325,146
Wages payable	21,014	21,091
Accrued interest	13,118	7,835
Dividends declared	25,221	23,377
Customer deposits and advance payments	80,772	88,897
Gas costs and other regulatory liabilities	14,751	34,551
Accrued taxes	33,694	13,867
Derivatives	79,558	63,504
Liabilities held for sale	0	1,621
Other	35,293	46,025
Total current liabilities	994,923	982,914
Deferred Credits
Unamortized investment tax credits	157,200	135,673
Deferred income taxes	743,677	672,963
Accrued pensions and benefits	186,696	176,128
Asset retirement obligations	209,451	200,732
Regulatory liabilities
Accrued asset removal costs	311,469	325,496
Other post-retirement benefits	94,194	104,382
Other	15,976	17,067
Derivatives	274,097	322,259
Other	121,601	108,124
Total deferred credits	2,114,361	2,062,824
Commitments and Contingencies (Note 13)
Total Capitalization and Liabilities	5,742,813	5,261,359
Washington Gas Light Company
Property, Plant and Equipment
At original cost	4,757,194	4,521,535
Accumulated depreciation and amortization	(1,322,709)	(1,278,089)
Net property, plant and equipment	3,434,485	3,243,446
Current Assets
Cash and cash equivalents	1	1
Receivables
Accounts receivable	155,288	126,356
Gas costs and other regulatory assets	17,106	5,797
Unbilled revenues	75,939	21,027
Allowance for doubtful accounts	(17,760)	(19,254)
Net receivables	230,573	133,926
Materials and supplies—principally at average cost	18,608	21,356
Storage gas	55,943	94,489
Prepaid taxes	40,118	30,365
Other prepayments	21,654	11,899
Receivables from associated companies	11,488	3,176
Derivatives	4,131	4,588
Assets held for sale	0	22,906
Other	52	0
Total current assets	382,568	322,706
Regulatory assets
Gas costs	153,075	190,676
Pension and other post-retirement benefits	193,134	210,811
Other	99,718	79,946
Prepaid post-retirement benefits	152,032	137,754
Derivatives	20,378	13,155
Other	6,875	5,638
Total deferred charges and other assets	625,212	637,980
Total Assets	4,442,265	4,204,132
Capitalization
Common shareholders’ equity	1,152,403	1,081,292
Washington Gas Light Company preferred stock	28,173	28,173
Long-term debt	695,890	695,885
Total capitalization	1,876,466	1,805,350
Current Liabilities
Current maturities of long-term debt	0	25,000
Notes payable	202,342	89,000
Accounts payable and other accrued liabilities	175,500	159,280
Wages payable	19,141	19,456
Accrued interest	11,507	4,023
Dividends declared	21,446	20,269
Customer deposits and advance payments	78,325	88,450
Gas costs and other regulatory liabilities	14,751	34,551
Accrued taxes	23,706	11,659
Payables to associated companies	73,106	68,623
Derivatives	59,723	33,856
Liabilities held for sale	0	1,621
Other	7,023	7,013
Total current liabilities	686,570	562,801
Deferred Credits
Unamortized investment tax credits	5,042	5,646
Deferred income taxes	764,029	668,764
Accrued pensions and benefits	184,828	174,318
Asset retirement obligations	205,882	198,938
Regulatory liabilities
Accrued asset removal costs	311,469	325,496
Other post-retirement benefits	93,582	103,683
Other	15,976	17,067
Derivatives	225,763	269,661
Other	72,658	72,408
Total deferred credits	1,879,229	1,835,981
Commitments and Contingencies (Note 13)
Total Capitalization and Liabilities	$ 4,442,265	$ 4,204,132

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
OPERATING REVENUES
Utility		$ 181,622	$ 185,179	$ 912,612	$ 1,173,396
Non-utility		258,965	255,994	977,048	1,018,747
Total Operating Revenues	[1]	440,587	441,173	1,889,660	2,192,143
OPERATING EXPENSES
Utility cost of gas		65,739	59,286	236,819	499,128
Non-utility cost of energy-related sales		197,880	240,808	832,087	933,911
Operation and maintenance		97,461	98,642	296,813	295,309
Depreciation and Amortization		33,786	30,696	98,368	90,159
General taxes and other assessments		32,038	29,308	119,970	126,475
Total Operating Expenses		426,904	458,740	1,584,057	1,944,982
OPERATING INCOME (LOSS)		13,683	(17,567)	305,603	247,161
Equity in earnings of unconsolidated affiliates		4,527	1,262	10,558	4,238
Other income (expenses)—net		1,915	2,329	3,689	(1,688)
Interest expense		12,998	13,140	38,757	38,704
INCOME (LOSS) BEFORE INCOME TAXES		7,127	(27,116)	281,093	211,007
INCOME TAX EXPENSE (BENEFIT)		4,772	(11,756)	103,619	80,364
NET INCOME (LOSS)		2,355	(15,360)	177,474	130,643
Dividends on Washington Gas Light Company preferred stock		330	330	990	990
NET INCOME (LOSS) APPLICABLE TO COMMON STOCK		$ 2,025	$ (15,690)	$ 176,484	$ 129,653
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Basic (in shares)		50,622	49,729	50,158	49,814
Diluted (in shares)		50,905	49,729	50,418	50,056
EARNINGS (LOSS) PER AVERAGE COMMON SHARE
Basic (in dollars per share)		$ 0.04	$ (0.32)	$ 3.52	$ 2.60
Diluted (in dollars per share)		0.04	(0.32)	3.50	2.59
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)		$ 0.4875	$ 0.4625	$ 1.4375	$ 1.3650
Washington Gas Light Company
OPERATING REVENUES
Utility		$ 187,077	$ 190,345	$ 934,347	$ 1,193,232
OPERATING EXPENSES
Utility cost of gas		71,194	64,452	258,554	518,945
Operation and maintenance		79,178	80,077	239,696	240,714
Depreciation and Amortization		29,232	27,348	85,194	80,832
General taxes and other assessments		28,001	25,197	108,228	114,903
Total Operating Expenses		207,605	197,074	691,672	955,394
OPERATING INCOME (LOSS)		(20,528)	(6,729)	242,675	237,838
Other income (expenses)—net		(358)	(129)	(1,079)	(748)
Interest expense		10,067	10,637	30,785	31,465
INCOME (LOSS) BEFORE INCOME TAXES		(30,953)	(17,495)	210,811	205,625
INCOME TAX EXPENSE (BENEFIT)		(12,434)	(6,071)	80,285	77,404
NET INCOME (LOSS)		(18,519)	(11,424)	130,526	128,221
Dividends on Washington Gas Light Company preferred stock		330	330	990	990
NET INCOME (LOSS) APPLICABLE TO COMMON STOCK		$ (18,849)	$ (11,754)	$ 129,536	$ 127,231
[1]	Operating revenues are reported gross of revenue taxes. Operating revenue amounts in the “Eliminations” row represent total intersegment revenues associated with sales from the regulated utility segment to the retail energy-marketing segment. Midstream Energy Services’ cost of energy related sales is netted with its gross revenues.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net income (loss)		$ 2,355	$ (15,360)	$ 177,474	$ 130,643
OTHER COMPREHENSIVE INCOME, BEFORE INCOME TAXES:
Qualified cash flow hedging instruments	[1]	(16,995)	49	(34,545)	(7,994)
Pension and other post-retirement benefit plans
Change in net prior service credit	[2]	(216)	(170)	(644)	(511)
Change in actuarial net loss	[2]	420	529	1,258	1,503
Total pension and other post-retirement benefit plans		204	359	614	992
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME		(6,969)	163	(14,087)	(3,565)
OTHER COMPREHENSIVE INCOME (LOSS)		(9,822)	245	(19,844)	(3,437)
COMPREHENSIVE INCOME (LOSS)		(7,467)	(15,115)	157,630	127,206
Washington Gas Light Company
Net income (loss)		(18,519)	(11,424)	130,526	128,221
Pension and other post-retirement benefit plans
Change in net prior service credit	[3]	(216)	(170)	(644)	(511)
Change in actuarial net loss	[3]	420	529	1,258	1,503
Total pension and other post-retirement benefit plans		204	359	614	992
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME		82	143	244	394
OTHER COMPREHENSIVE INCOME (LOSS)		122	216	370	598
COMPREHENSIVE INCOME (LOSS)		$ (18,397)	$ (11,208)	$ 130,896	$ 128,819
[1]	Cash flow hedging instruments represent interest rate swap agreements related to future debt issuances. Refer to Note 8- Derivative and Weather-related Instruments for further discussion of the interest rate swap agreements.
[2]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14- Pension and other post-retirement benefit plans for additional details.
[3]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14-Pension and other post-retirement benefit plans for additional details.

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
OPERATING ACTIVITIES
Net income	$ 177,474	$ 130,643
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and Amortization	98,368	90,159
Amortization of:
Other regulatory assets and liabilities—net	1,113	981
Debt related costs	967	911
Deferred income taxes—net	131,494	36,156
Accrued/deferred pension and other post-retirement benefit cost	14,832	20,091
Earnings in equity interest	(11,491)	(3,610)
Compensation expense related to stock-based awards	9,745	11,051
Provision for doubtful accounts	8,752	15,411
Impairment loss	3,000	5,625
Other non-cash credits—net	(1,449)	(617)
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable and unbilled revenues—net	(68,380)	(83,076)
Gas costs and other regulatory assets/liabilities—net	(31,109)	5,025
Storage gas	38,725	186,096
Prepaid taxes	(63,795)	56,818
Other prepayments	(11,429)	(3,879)
Accounts payable and other accrued liabilities	(19)	(18,966)
Customer deposits and advance payments	(8,125)	5,013
Unamortized investment tax credits	21,527	17,162
Accrued taxes	19,827	23,240
Accrued interest	5,283	10,166
Other current assets	(6,032)	3,609
Other current liabilities	(15,472)	10,354
Deferred gas costs—net	37,601	11,954
Deferred assets—other	(34,010)	(17,953)
Deferred liabilities—other	(12,721)	(61,791)
Derivatives	(71,078)	62,784
Other—net	1,838	(360)
Net Cash Provided by Operating Activities	235,436	512,997
FINANCING ACTIVITIES
Common stock issued	78,050	0
Long-term debt issued	250,000	296,481
Long-term debt retired	(25,000)	0
Debt issuance costs	(284)	(2,744)
Notes payable retired —net	(26,000)	(297,500)
Project financing	28,425	0
Dividends on common stock and preferred stock	(68,970)	(67,986)
Repurchase of common stock	0	(41,485)
Other financing activities—net	1,998	0
Net Cash Provided by (Used in) Financing Activities	238,219	(113,234)
INVESTING ACTIVITIES
Capital expenditures (excluding AFUDC)	(348,594)	(317,043)
Investments in non-utility interests	(137,105)	(29,618)
Distributions and receipts from non-utility interests	4,739	4,138
Net proceeds from sale of assets	19,749	0
Loans to external parties	(2,643)	0
Net Cash Used in Investing Activities	(463,854)	(342,523)
INCREASE IN CASH AND CASH EQUIVALENTS	9,801	57,240
Cash and Cash Equivalents at Beginning of Year	6,733	8,811
Cash and Cash Equivalents at End of Period	16,534	66,051
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid—net	3,032	4,604
Interest paid	33,080	27,822
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Project financing activities	0	(2,032)
Capital expenditure accruals included in accounts payable and other accrued liabilities	51,814	30,489
Dividends paid in common stock	2,661	0
Stock issued related to compensation	6,742	0
Washington Gas Light Company
OPERATING ACTIVITIES
Net income	130,526	128,221
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and Amortization	85,194	80,832
Amortization of:
Other regulatory assets and liabilities—net	1,113	981
Debt related costs	898	967
Deferred income taxes—net	90,032	28,568
Accrued/deferred pension and other post-retirement benefit cost	3,221	19,610
Compensation expense related to stock-based awards	8,431	12,518
Provision for doubtful accounts	7,094	10,520
Other non-cash credits—net	318	2,344
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable and unbilled revenues—net	(75,427)	(50,035)
Gas costs and other regulatory assets/liabilities—net	(31,109)	5,025
Storage gas	38,546	95,735
Prepaid taxes	(9,753)	0
Other prepayments	(9,755)	12,513
Accounts payable and other accrued liabilities	18,288	(19,746)
Customer deposits and advance payments	(10,125)	4,766
Accrued taxes	12,047	32,999
Accrued interest	7,484	8,641
Other current assets	2,696	3,980
Other current liabilities	(4,656)	452
Deferred gas costs—net	37,601	11,954
Deferred assets—other	(22,216)	(17,430)
Deferred liabilities—other	(14,436)	(9,013)
Derivatives	(24,797)	29,104
Other—net	(399)	(835)
Net Cash Provided by Operating Activities	240,816	392,671
FINANCING ACTIVITIES
Long-term debt issued	0	50,000
Long-term debt retired	(25,000)	0
Debt issuance costs	(171)	(722)
Notes payable retired —net	61,000	(89,000)
Project financing	28,425	0
Dividends on common stock and preferred stock	(61,669)	(59,542)
Other financing activities—net	2,891	0
Net Cash Provided by (Used in) Financing Activities	5,476	(99,264)
INVESTING ACTIVITIES
Capital expenditures (excluding AFUDC)	(266,041)	(232,697)
Net proceeds from sale of assets	19,749	0
Net Cash Used in Investing Activities	(246,292)	(232,697)
INCREASE IN CASH AND CASH EQUIVALENTS	0	60,710
Cash and Cash Equivalents at Beginning of Year	1	1,060
Cash and Cash Equivalents at End of Period	1	61,770
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid—net	21	3,711
Interest paid	25,108	20,583
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Project financing activities	0	(2,032)
Capital expenditure accruals included in accounts payable and other accrued liabilities	$ 41,264	$ 25,367

Accounting Policies

Accounting Policies	9 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Accounting Policies	ACCOUNTING POLICIES Basis of Presentation WGL Holdings, Inc. (WGL) is a holding company that owns all of the shares of common stock of Washington Gas Light Company (Washington Gas), a regulated natural gas utility, and all of the shares of common stock of Washington Gas Resources Corporation (Washington Gas Resources) and Hampshire Gas Company (Hampshire). Washington Gas Resources owns all of the shares of common stock of four non-utility subsidiaries that include WGL Energy Services, Inc. (WGL Energy Services), WGL Energy Systems, Inc. (WGL Energy Systems), WGL Midstream, Inc. (WGL Midstream) and WGSW, Inc. (WGSW). Except where the content clearly indicates otherwise, “WGL,” “we,” “us” or “our” refers to the holding company or the consolidated entity of WGL Holdings, Inc. and all of its subsidiaries. Unless otherwise noted, these notes apply equally to WGL and Washington Gas. The condensed consolidated financial statements 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 consolidated financial statements and accompanying notes should be read in conjunction with the combined Annual Report on Form 10-K for WGL and Washington Gas for the fiscal year ended September 30, 2015 and the current report on Form 8-K filed on March 16, 2016, which amended the Annual Report on Form 10-K to recast the balance sheet for the October 1, 2015 adoption of ASU 2015-17, Income Taxes: Balance Sheet Classification of Deferred Taxes . Due to the seasonal nature of our businesses, the results of operations for the periods presented in this report are not necessarily indicative of actual results for the full fiscal years ending September 30, 2016 and 2015 , of either WGL or Washington Gas. The accompanying unaudited financial statements for WGL and Washington Gas reflect all normal recurring adjustments that are necessary, in our opinion, to present fairly the results of operations in accordance with GAAP. Prior period amounts related to deferred income tax assets and liabilities in the accompanying condensed balance sheets have been reclassified to conform to the current period presentation. Refer to Note 7 — Income Taxes of the Notes to Condensed Consolidated Financial Statements. For a complete description of our accounting policies, refer to Note 1 of the Notes to Consolidated Financial Statements of the combined Annual Report on Form 10-K for WGL and Washington Gas for the fiscal year ended September 30, 2015 . Asset Sale - Building On June 1, 2016, Washington Gas completed the sale of the Springfield Operation Center for approximately $ 20.3 million , net of selling and administrative expenses of $ 0.5 million . Washington Gas recorded multiple impairment charges in prior years, related to the asset and selling costs. As a result of the sale, an additional minimal loss was recorded to "Other expense-net" in the accompanying Consolidated Statements of Income. At September 30, 2015 , the assets and liabilities associated with the Springfield Operations Center were reported at their expected selling price, less selling expenses, as "Assets held for sale" and "Liabilities held for sale" on WGL's and Washington Gas' balance sheets. Impairments Management regularly reviews property and equipment and other long-lived assets, including certain definite-lived intangible assets and our equity method investments for possible impairment. For our equity and cost method investments, an impairment is recorded when the investment has experienced a decline in value that is other-than-temporary. Additionally, if the projects in which we hold an investment recognize an impairment loss, we would record our proportionate share of that impairment loss and evaluate the investment for decline in value that is other-than-temporary. This review occurs quarterly, or more frequently if events or changes in circumstances indicate the carrying amount of the asset may not be recoverable. During the nine months ended June 30, 2016 , WGL recorded a $3.0 million impairment for the Nextility investment in direct financing leases. During the nine months ended June 30, 2015 , WGL impaired its entire investment in ASDHI by its carrying value of $5.6 million based on management's assumption of the current valuation and expected return from the investment. Refer to Note 9 — Fair Value Measurements and Note 11 — Other Investments of the Notes to Condensed Consolidated Financial Statements for further discussion. Storage Gas Valuation For Washington Gas and WGL Energy Services, storage gas inventories are accounted for using the first-in, first-out method. For WGL Midstream, storage gas inventory is accounted for using the weighted average cost method. Our inventory is stated at the lower-of-cost or market. Interim period inventory losses attributable to lower-of-cost or market adjustments may be reversed if the market value of the inventory is recovered by the end of the same fiscal year. The following table shows the lower-of-cost or market adjustments recorded to net income for the three and nine months ended June 30, 2016 and 2015 . Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income Three Months Ended June 30, Nine Months Ended June 30, (In millions) 2016 2015 2016 2015 WGL (a) Operating revenues - non-utility $ 0.7 $ 0.9 $ (0.4 ) $ (19.6 ) Washington Gas Utility cost of gas — — $ — $ (1.0 ) Total Consolidated $ 0.7 $ 0.9 $ (0.4 ) $ (20.6 ) (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. ACCOUNTING STANDARDS ADOPTED IN FISCAL YEAR 2016 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes The standard requires an entity to present deferred tax liabilities and assets as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets of a tax-paying component of an entity be offset by taxing jurisdiction and presented as a single amount remains the same. October 1, 2015 As a result of the standard, we have presented all deferred tax liabilities and assets, net, as non-current in "Deferred credits-Deferred income taxes" in the accompanying balance sheets, retrospectively for all periods presented. The adoption of this standard did not have a material effect on our financial statements. Refer to Note 7 — Income taxes , for further discussion of this standard. OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required 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 For credit losses on financial instruments, 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. October 1, 2020 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting This standard simplifies several aspects of the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and statutory tax withholding requirements. October 1, 2017 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2014-09, Revenue from Contracts with Customers (Topic 606), including subsequent ASUs clarifying the guidance. ASU 2014-09 establishes a comprehensive revenue recognition model clarifying the method used to determine the timing and requirements for revenue recognition from contracts with customers. The disclosure requirements under the new standard will enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-02, Leases (Topic 842) This standard requires recognition of a right-to-use asset and lease liability on the statement of financial position and disclosure of key information about leasing arrangements. The standard requires application using a modified retrospective approach. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. We may elect early adoption. ASU 2016-01, Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The new standard significantly revises an entity’s accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2015-03 and ASU 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost and Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements The standard requires an entity to present debt issuance costs in the balance sheet as a direct deduction of the debt liability in a manner consistent with its accounting treatment of debt discounts. The standard requires retrospective application. An entity can defer and present debt issuance costs related to line-of-credit arrangements as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. October 1, 2016 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis The standard changes the analysis to be performed in determining whether certain types of legal entities should be consolidated, specifically the analysis of limited partnerships and similar entities, fee arrangements and related party relationships. The standard permits prospective or retrospective application for different parts. October 1, 2016 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.

Accounts Payable and Other Accr

Accounts Payable and Other Accrued Liabilities	9 Months Ended
	Jun. 30, 2016
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable and Other Accrued Liabilities	ACCOUNTS PAYABLE AND OTHER ACCRUED LIABILITIES The tables below provide details for the amounts included in “Accounts payable and other accrued liabilities” on the balance sheets for both WGL and Washington Gas. WGL Holdings, Inc. (In millions) June 30, 2016 September 30, 2015 Accounts payable—trade $ 290.1 $ 277.3 Employee benefits and payroll accruals 27.7 31.4 Other accrued liabilities 15.4 16.4 Total $ 333.2 $ 325.1 Washington Gas Light Company (In millions) June 30, 2016 September 30, 2015 Accounts payable—trade $ 141.3 $ 122.2 Employee benefits and payroll accruals 25.8 29.5 Other accrued liabilities 8.4 7.6 Total $ 175.5 $ 159.3

Short-Term Debt

Short-Term Debt	9 Months Ended
	Jun. 30, 2016
Short-term Debt [Abstract]
Short-Term Debt	SHORT-TERM DEBT WGL and Washington Gas satisfy their short-term financing requirements through the sale of commercial paper, financing arrangements with third-party lenders, or through bank borrowings. Due to the seasonal nature of the regulated utility and retail energy-marketing segments, 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 each WGL and Washington Gas is to maintain bank credit facilities in amounts equal to or greater than the expected maximum commercial paper position. The following is a summary of committed credit available at June 30, 2016 and September 30, 2015 . Committed Credit Available ($ In millions) June 30, 2016 WGL (b) Washington Gas Total Consolidated Committed credit agreements Unsecured revolving credit facility, expires December 19, 2019 (a) $ 450.0 $ 350.0 $ 800.0 Less: Commercial Paper (156.0 ) (150.0 ) (306.0 ) Net committed credit available $ 294.0 $ 200.0 $ 494.0 Weighted average interest rate 0.68 % 0.48 % 0.58 % September 30, 2015 Committed credit agreements Unsecured revolving credit facility, expires December 19, 2019 (a) $ 450.0 $ 350.0 $ 800.0 Less: Commercial Paper (243.0 ) (89.0 ) (332.0 ) Net committed credit available $ 207.0 $ 261.0 $ 468.0 Weighted average interest rate 0.30 % 0.16 % 0.26 % (a) Both WGL and Washington Gas have the right to request extensions with the banks’ approval. WGL’s revolving credit facility permits it to borrow an additional $100 million , with the banks’ approval, for a total of $550 million . Washington Gas’ revolving credit facility permits it to borrow an additional $100 million , with the banks’ approval, for a total of $450 million . (b) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. At June 30, 2016 and September 30, 2015 , there were no outstanding bank loans from WGL’s or Washington Gas’ revolving credit facilities. PROJECT FINANCING Washington Gas obtains third-party project financing on behalf of the Federal government to provide funds during the construction of certain energy management services projects entered into under Washington Gas' area-wide contract. As the lender funds the energy management services project, Washington Gas establishes a payable to the lender. As work is performed, Washington Gas establishes a receivable representing the government's obligation to remit principal and interest. The payable and receivable are equal to each other at the end of the construction period, but there could be timing differences in the recognition of the project related payable and receivable during the construction period. When these projects are formally “accepted” by the government and deemed complete, Washington Gas assigns the ownership of the receivable to the lender in satisfaction of the obligation to the lender and removes both the receivable and the obligation related to the financing from its financial statements. As of June 30, 2016 , Washington Gas recorded a $56.6 million "Accounts receivable" on the balance sheet and a $ 52.3 million corresponding short-term obligation to the lender in "Notes payable", for energy management services projects that were not complete. Because these projects are financed for government agencies which have minimal credit risk, and with which we have previous collection experience, Washington Gas did not record a corresponding reserve for bad debts related to these receivables at June 30, 2016 .

Long-Term Debt

Long-Term Debt	9 Months Ended
	Jun. 30, 2016
Long-term Debt, by Current and Noncurrent [Abstract]
Long-Term Debt	LONG-TERM DEBT UNSECURED NOTES WGL and Washington Gas issue long-term notes with individual terms regarding interest rates, maturities and call or put options. These notes can have maturity dates of one or more years from the date of issuance. At June 30, 2016 and September 30, 2015 , WGL had the capacity under a shelf registration to issue an unspecified amount of long-term debt securities. At June 30, 2016 and September 30, 2015 Washington Gas had the capacity under a shelf registration statement to issue up to $600.0 million of additional Medium-Term Notes (MTNs). On February 18, 2016, WGL entered into a credit agreement providing for a term loan facility and borrowed $250 million under the agreement. The credit agreement provides for a maturity date of February 18, 2018 , with a one year extension option with the lenders' approval. In addition to the initial borrowings, the credit agreement permits, with the lenders' approval, additional borrowings of up to $100 million , for maximum potential borrowings under the credit agreement of $350 million . The interest rate on loans made under the credit agreement will be a fluctuating rate that will be determined from time to time based on parameters set forth in the credit agreement. The following tables show the outstanding notes as of June 30, 2016 and September 30, 2015 . Long-Term Debt Outstanding ($ In millions) WGL (a) Washington Gas Total Consolidated June 30, 2016 Long-term debt (b) $ 500.0 $ 696.0 $ 1,196.0 Unamortized discount (1.6 ) (0.1 ) (1.7 ) Total Long-Term Debt $ 498.4 $ 695.9 $ 1,194.3 Weighted average interest rate 2.45 % 5.59 % 4.28 % September 30, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 Unamortized discount (1.7 ) (0.1 ) (1.8 ) Less—current maturities — (25.0 ) (25.0 ) Total Long-Term Debt $ 248.3 $ 695.9 $ 944.2 Weighted average interest rate 3.66 % 5.58 % 5.08 % (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. (b) Includes Senior Notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities. The following tables show long-term debt issuances and retirements for the nine months ended June 30, 2016 and 2015 . There were no retirements for WGL or Washington Gas for the nine months ended June 30, 2015 . Long-Term Debt Issuances and Retirements ($ In millions) Principal (b) Interest Rate Effective Cost (d) Nominal Maturity Date Nine Months Ended June 30, 2016 WGL (a) Issuances: 2/18/2016 $ 250.0 1.25 % (c) 1.25 % 2/18/2018 Total consolidated issuances $ 250.0 Washington Gas Retirements: 1/18/2016 $ 25.0 5.17 % n/a 1/18/2016 Total consolidated retirements $ 25.0 Nine Months Ended June 30, 2015 WGL (a) Issuances: 10/24/2014 $ 100.0 2.25 % 2.42 % 11/1/2019 10/24/2014 125.0 4.60 % 5.11 % 11/1/2044 12/16/2014 25.0 4.60 % 5.53 % 11/1/2044 Total $ 250.0 Washington Gas Issuances: 12/15/2014 $ 50.0 4.24 % 4.41 % 12/15/2044 Total $ 50.0 Total consolidated issuances $ 300.0 (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. (b) Represents face amount of senior notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. (c) Floating rate per annum that will be determined from time to time based on parameters set forth in the credit agreement. (d) The estimated effective cost of the issued notes.

Common Shareholders' Equity

Common Shareholders' Equity	9 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Common Shareholders' Equity	COMMON SHAREHOLDERS’ EQUITY The tables below reflect the components of “Common shareholders’ equity” for WGL and “Common shareholder’s equity” for Washington Gas for the nine months ended June 30, 2016 . WGL Holdings, Inc. Components of Common Shareholders’ Equity (In thousands, except shares) Common Stock Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss, Net of Taxes Total Shares Amount Balance at September 30, 2015 49,728,662 $ 485,456 $ 14,934 $ 757,093 $ (14,236 ) $ 1,243,247 Net income — — — 177,474 — 177,474 Other comprehensive loss — — — — (19,844 ) (19,844 ) Stock-based compensation (a) 115,974 6,742 (3,652 ) (122 ) — 2,968 Issuance of common stock (b) 1,213,373 80,711 — — — 80,711 Dividends declared: Common stock — — — (72,485 ) — (72,485 ) Preferred stock — — — (990 ) — (990 ) Balance at June 30, 2016 51,058,009 $ 572,909 $ 11,282 $ 860,970 $ (34,080 ) $ 1,411,081 (a) Includes dividend equivalents related to our performance shares. (b) Includes shares issued under the ATM program (discussed below) and the dividend reinvestment and common stock purchase plans. Washington Gas Light Company Components of Common Shareholder’s Equity (In thousands, except shares) Common Stock Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss, Net of Taxes Total Shares Amount Balance at September 30, 2015 46,479,536 $ 46,479 $ 483,677 $ 557,848 $ (6,712 ) $ 1,081,292 Net income — — — 130,526 — 130,526 Other comprehensive income — — — — 370 370 Stock-based compensation — — 2,119 — — 2,119 Dividends declared: Common stock — — — (61,856 ) — (61,856 ) Preferred stock — — — (990 ) — (990 ) Other (a) 942 942 Balance at June 30, 2016 46,479,536 $ 46,479 $ 486,738 $ 625,528 $ (6,342 ) $ 1,152,403 (a) Represents a WGL contribution related to the transfer of a storage contract to an affiliate. On November 24, 2015, WGL entered into an equity distribution agreement and filed a prospectus supplement relating to a continuous offering under which WGL may sell common stock with an aggregate sales price of up to $150 million through an at-the-market (ATM) program. Sales of common stock can be made by means of privately negotiated transactions, as transactions on the New York Stock Exchange at market prices or in such other transactions as agreed upon by WGL and the sales agents and in accordance with applicable securities laws. During the nine months ended June 30, 2016 , WGL has issued 1,162,305 shares of common stock under the ATM program for gross proceeds of $78.2 million .

Earnings Per Share

Earnings Per Share	9 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic EPS of WGL is computed by dividing net income by the weighted average number of common shares outstanding during the reported period. Diluted EPS assumes the issuance of common shares pursuant to stock-based compensation plans at the beginning of the applicable period unless the effect of such issuance would be anti-dilutive. The following table reflects the computation of our basic and diluted EPS for the three and nine months ended June 30, 2016 and 2015 . Basic and Diluted EPS (In thousands, except per share data) Net Income (Loss) Applicable to Common Stock Shares Per Share Amount Three Months Ended June 30, 2016 Basic EPS $ 2,025 50,622 $ 0.04 Stock-based compensation plans — 283 Diluted EPS $ 2,025 50,905 $ 0.04 Three Months Ended June 30, 2015 Basic EPS $ (15,690 ) 49,729 $ (0.32 ) Stock-based compensation plans — — Diluted EPS $ (15,690 ) 49,729 $ (0.32 ) Nine Months Ended June 30, 2016 Basic EPS $ 176,484 50,158 $ 3.52 Stock-based compensation plans — 260 Diluted EPS $ 176,484 50,418 $ 3.50 Nine Months Ended June 30, 2015 Basic EPS $ 129,653 49,814 $ 2.60 Stock-based compensation plans — 242 Diluted EPS $ 129,653 50,056 $ 2.59 There were no anti-dilutive shares for the three and nine months ended June 30, 2016 or the nine months ended June 30, 2015 . We incurred a net loss for the three months June 30, 2015 ; therefore, all common shares issuable pursuant to stock-based compensation plans, were not considered in the diluted loss per share calculation due to the anti-dilutive effect of such shares. These shares included 317,000 of performance shares for the three months ended June 30, 2015.

Income Taxes

Income Taxes	9 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES As of both June 30, 2016 and September 30, 2015 , our uncertain tax positions were approximately $38.6 million , primarily due to the change in tax accounting for repairs. If the amounts of unrecognized tax benefits are eventually realized, it would not materially impact the effective tax rate. It is reasonably possible that the amount of the unrecognized tax benefit with respect to some of WGL’s and Washington Gas’ uncertain tax positions will significantly increase or decrease in the next 12 months. At this time, however, an estimate of the range of reasonably possible outcomes cannot be determined. Under ASC Topic 740, Income Taxes , Washington Gas recognizes any accrued interest associated with uncertain tax positions in interest expense and recognizes any accrued penalties associated with uncertain tax positions in other expenses in the statements of income. At June 30, 2016 and September 30, 2015, we did not have an accrual of interest expense related to uncertain tax positions. WGL files a consolidated federal tax return and various other state returns. We are no longer subject to income tax examinations by the Internal Revenue Service for years ended prior to September 30, 2012. Substantially all state income tax years in major jurisdictions are closed for years ended prior to September 30, 2011. On October 1, 2015, WGL and Washington Gas early adopted ASU 2015-17. This standard amends the requirements to separately classify deferred income tax liabilities and assets into current and noncurrent amounts on a classified balance sheet and requires all deferred income tax liabilities and assets to be offset by taxing jurisdiction and classified as noncurrent. WGL and Washington Gas are applying ASU 2015-17 retrospectively. As a result of the retrospective adoption, $32.8 million and $24.7 million for WGL and Washington Gas, respectively, were reclassified from "Current Assets-Deferred income taxes" to "Deferred Credits-Deferred income taxes" on WGL's and Washington Gas' September 30, 2015 balance sheets.

Derivative and Weather Related

Derivative and Weather Related Instruments	9 Months Ended
	Jun. 30, 2016
Derivative Instrument Detail [Abstract]
Derivative and Weather-Related Instruments	DERIVATIVE AND WEATHER-RELATED INSTRUMENTS DERIVATIVE INSTRUMENTS Regulated Utility Operations 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 locking in 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 280. Regulatory sharing mechanisms provide for the annual realized profit from these transactions to be shared between Washington Gas' shareholders 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 locked-in operating margins that Washington Gas expects to ultimately realize from these transactions through the use of its storage and transportation capacity resources. All physically and financially settled contracts under our asset optimization program are reported on a net basis in the statements of income 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 June 30, 2016 was a net loss of $19.0 million including an unrealized loss of $25.2 million . During the three months ended June 30, 2015 we recorded a net loss of $2.9 million including an unrealized loss of $10.4 million . Total net margins recorded for the nine months ended June 30, 2016 was a net gain of $30.3 million including an unrealized gain of $8.0 million . During the nine months ended June 30, 2015 , we recorded a net gain of $14.2 million including an unrealized loss of $13.3 million . 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. Managing Interest-Rate Risk . Washington Gas may utilize derivative instruments that are designed to minimize the risk of interest-rate volatility associated with planned issuances of debt securities. Any gains and losses associated with these types of derivatives are recorded as regulatory liabilities or assets, respectively, and amortized in accordance with regulatory requirements, typically over the life of the related debt. In May 2016, Washington Gas entered into a forward starting interest rate swap, with a notional amount of $ 125.0 million related to the expected issuance of 30-year debt in late 2016. The change in the fair value of the interest rate swap is reported as a regulatory asset. Non-Utility Operations Asset Optimization. WGL Midstream enters into derivative contracts for the purpose of optimizing its storage and transportation capacity as well as managing the transportation and storage assets on behalf of third parties. WGL Midstream does not designate these derivatives as hedges under ASC Topic 815; therefore, changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations and may cause significant period-to-period volatility in earnings. Managing Price Risk. WGL Energy Services enters into certain derivative contracts as part of its strategy to manage the price risk associated with the sale and purchase of natural gas and electricity. WGL Energy Services designates a portion of these physical contracts related to the purchase of natural gas and electricity to serve our customers as "normal purchases and normal sales" and therefore, they are not subject to the fair value accounting requirements of ASC Topic 815. Derivative instruments not designated as "normal purchases and normal sales" are recorded at fair value on our consolidated balance sheets, and changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations, which may cause significant period-to-period volatility in earnings. WGL Energy Services does not designate derivatives as hedges under ASC Topic 815. Managing Interest-Rate Risk . WGL utilizes derivative instruments that are designed to limit the risk of interest-rate volatility associated with future debt issuances. Through the nine months ended June 30, 2016, WGL entered into two forward starting interest rate swaps with a total notional amount outstanding of $75.0 million . In August 2015, WGL entered into two forward starting interest rate swap agreements with a total notional amount outstanding of $125.0 million . These derivatives hedge the variability in future interest payments associated with WGL's expected issuance of 30-year debt in January 2018. WGL designated these interest rate swaps as cash flow hedges. The effective portion of changes in fair value is reported as a component of other comprehensive income (loss) and reclassified into earnings in the same line item associated with the forecasted transaction and in the same period or periods during which the hedged transaction affects earnings. Any ineffective portion of these derivatives will be recognized directly through earnings as interest expense. There has been no ineffectiveness recorded to income associated with these hedges. Additionally, WGL elected cash flow hedge accounting for interest rate swaps, which settled with the issuance of the related debt issuance in the first quarter of fiscal 2015. The effective portion of the gains and losses on the hedge were recorded within other comprehensive income (loss) and are amortized over the life of the debt (through 2044). The amortization was minimal for the three and nine months ended June 30, 2016 and 2015 . Consolidated Operations Reflected in the tables below is information for WGL as well as Washington Gas. The information for WGL includes derivative instruments for both utility and non-utility operations. At June 30, 2016 and September 30, 2015 , respectively, the absolute notional amounts of our derivatives were as follows: Absolute Notional Amounts of Open Positions on Derivative Instruments Derivative transactions WGL Holdings, Inc. Washington Gas June 30, 2016 Notional Amounts Natural Gas (In millions of therms) Asset Optimization 22,365.5 13,180.0 Retail sales 54.3 — Other risk-management activities 1,819.4 1,322.0 Electricity (In millions of kWhs) Retail sales 4,874.5 — Other risk-management activities (a) 25,300.1 — Interest Rate Swaps (In millions of dollars) $ 325.0 $ 125.0 September 30, 2015 Natural Gas (In millions of therms) Asset Optimization 20,829.2 13,316.7 Retail sales 52.2 — Other risk-management activities 1,811.7 1,381.8 Electricity (In millions of kWhs) Retail sales 4,292.7 — Other risk-management activities (a) 19,965.7 — Interest Rate Swaps (In millions of dollars) $ 125.0 $ — (a) Comprised primarily of electric swaps, financial transmission rights, physical forward purchases and slice of system, if any. The following tables present the balance sheet classification for all derivative instruments as of June 30, 2016 and September 30, 2015 . WGL Holdings, Inc. Balance Sheet Classification of Derivative Instruments ($ In millions) Derivative Instruments Not Designated as Hedging Instruments Derivative Instruments Designated as Hedging Instruments As of June 30, 2016 Gross Derivative Assets Gross Derivative Liabilities Gross Derivative Assets Gross Derivative Liabilities Netting of Collateral Total (a) Current Assets—Derivatives $ 27.5 $ (11.0 ) $ — $ — $ — $ 16.5 Deferred Charges and Other Assets—Derivatives 43.2 (0.2 ) — — — 43.0 Current Liabilities—Derivatives 39.5 (139.3 ) — — 20.2 (79.6 ) Deferred Credits—Derivatives 21.0 (265.0 ) — (38.1 ) 8.0 (274.1 ) Total $ 131.2 $ (415.5 ) $ — $ (38.1 ) $ 28.2 $ (294.2 ) As of September 30, 2015 Current Assets—Derivatives $ 29.7 $ (6.8 ) $ — $ — $ — $ 22.9 Deferred Charges and Other Assets—Derivatives 32.3 (0.2 ) — — — 32.1 Current Liabilities—Derivatives 9.8 (76.2 ) — — 2.9 (63.5 ) Deferred Credits—Derivatives 2.7 (328.9 ) — (3.4 ) 7.3 (322.3 ) Total $ 74.5 $ (412.1 ) $ — $ (3.4 ) $ 10.2 $ (330.8 ) Washington Gas Light Company Balance Sheet Classification of Derivative Instruments (b) ($ In millions) As of June 30, 2016 Gross Gross Netting of Total (a) Current Assets—Derivatives $ 4.2 $ (0.1 ) $ — $ 4.1 Deferred Charges and Other Assets—Derivatives 20.4 — — 20.4 Current Liabilities—Derivatives 7.8 (67.6 ) 0.1 (59.7 ) Deferred Credits—Derivatives 2.5 (228.7 ) 0.4 (225.8 ) Total $ 34.9 $ (296.4 ) $ 0.5 $ (261.0 ) As of September 30, 2015 Current Assets—Derivatives $ 5.2 $ (0.6 ) $ — $ 4.6 Deferred Charges and Other Assets—Derivatives 13.3 (0.1 ) — 13.2 Current Liabilities—Derivatives 1.9 (35.8 ) — (33.9 ) Deferred Credits—Derivatives — (269.7 ) — (269.7 ) Total $ 20.4 $ (306.2 ) $ — $ (285.8 ) (a) WGL 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 815. All recognized derivative contracts and associated financial collateral subject to a master netting arrangement or similar that is eligible for offset under ASC 815 have been presented net in the balance sheet. (b) Washington Gas did not have any derivative instruments outstanding that were designated as hedging instruments at June 30, 2016 or September 30, 2015 . The following table presents all gains and losses associated with derivative instruments for the three and nine months ended June 30, 2016 and 2015 . Gains and Losses on Derivative Instruments ($ In millions) WGL Holdings, Inc. Washington Gas Three Months Ended June 30, 2016 2015 2016 2015 Recorded to income Operating revenues—non-utility $ (39.0 ) $ (28.3 ) $ — $ — Utility cost of gas (24.9 ) (10.4 ) (24.9 ) (10.4 ) Non-utility cost of energy-related sales 48.4 3.2 — — Interest expense (0.1 ) — — — Recorded to regulatory assets Gas costs (29.4 ) (12.1 ) (29.4 ) (12.1 ) Other (8.8 ) — (8.8 ) — Recorded to other comprehensive income (a) (16.9 ) — — — Total $ (70.7 ) $ (47.6 ) $ (63.1 ) $ (22.5 ) Nine Months Ended June 30, 2016 2015 2016 2015 Recorded to income Operating revenues—non-utility $ 7.6 $ 46.0 $ — $ — Utility cost of gas 9.2 (20.4 ) 9.2 (20.4 ) Non-utility cost of energy-related sales 50.6 (35.9 ) — — Interest expense (0.2 ) (0.5 ) — — Recorded to regulatory assets Gas costs 24.9 (36.0 ) 24.9 (36.0 ) Other (8.8 ) — (8.8 ) — Recorded to other comprehensive income (a) (34.5 ) (8.0 ) — — Total $ 48.8 $ (54.8 ) $ 25.3 $ (56.4 ) (a) Represents the effective portion of our cash flow hedges. Collateral WGL 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 parental 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 WGL’s 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 sheet. The table below presents collateral positions at June 30, 2016 and September 30, 2015 , respectively. Collateral Not Offset Against Derivative Assets and Liabilities (In millions) June 30, 2016 Collateral deposits posted with counterparties Cash collateral held representing an obligation Washington Gas $ 15.5 $ 0.1 WGL Energy Services 7.8 — WGL Midstream 8.1 2.4 September 30, 2015 Washington Gas $ 3.5 $ 3.8 WGL Energy Services 12.4 — WGL Midstream 3.5 0.4 Any collateral posted that is not offset against derivative assets and liabilities is included in “Other prepayments” in the accompanying balance sheets. Collateral received and not offset against derivative assets and liabilities is included in “Customer deposits and advance payments” in the accompanying balance sheets. Certain derivative instruments of WGL, Washington Gas, WGL Energy Services and WGL Midstream contain contract provisions that require collateral to be posted if the credit rating of Washington Gas or WGL falls below certain levels or if counterparty exposure to WGL, Washington Gas, WGL Energy Services or WGL Midstream exceeds a certain level. Due to counterparty exposure levels, at June 30, 2016 , WGL Energy Services posted $2.8 million of collateral related to its derivative liabilities that contained credit-related contingent features. At September 30, 2015 , WGL Energy Services posted $10.3 million of collateral related to these aforementioned derivative liabilities. At June 30, 2016 , WGL was required to post $4.8 million of collateral related to a derivative liability that contained a credit-related contingent feature. At September 30, 2015 , WGL was not required to post any collateral related to its derivative liabilities that contained credit-related contingent features. At both June 30, 2016 and September 30, 2015 , Washington Gas and WGL Midstream were not required to post any collateral related to their respective derivative liabilities that contained credit-related 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 June 30, 2016 and September 30, 2015 , respectively. Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features (In millions) WGL Holdings, Inc. Washington Gas June 30, 2016 Derivative liabilities with credit-risk-contingent features $ 46.3 $ 11.6 Maximum potential collateral requirements 30.7 11.0 September 30, 2015 Derivative liabilities with credit-risk-contingent features $ 61.7 $ 18.9 Maximum potential collateral requirements 54.6 18.8 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 June 30, 2016 , two counterparties represented over 10% of Washington Gas’ credit exposure to wholesale derivative counterparties for a total credit risk of $30.3 million ; four counterparties represented over 10% of WGL Energy Services’ credit exposure to wholesale counterparties for a total credit risk of $4.4 million ; and two counterparties represented over 10% of WGL Midstream’s credit exposure to wholesale counterparties for a total credit risk of $27.0 million . WEATHER-RELATED INSTRUMENTS WGL Energy Services utilizes weather-related instruments for managing the financial effects of weather risks. These instruments cover a portion of WGL Energy Services’ estimated revenue or energy-related cost exposure to variations in heating or cooling degree days. These contracts provide for payment to WGL Energy Services of a fixed-dollar amount for every degree day over or under specific levels during the calculation period depending upon the type of contract executed. For the three months ended June 30, 2016 and 2015 , WGL Energy Services recorded pre-tax losses of $0.5 million related to these contracts. For the nine months ended June 30, 2016 and 2015 , WGL Energy Services recorded pre-tax gains of $3.8 million and $2.7 million , respectively, related to these contracts.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Recurring Basis We measure the fair value of our financial assets and liabilities using a combination of the income and market approach in accordance with ASC Topic 820. These financial assets and liabilities primarily consist of derivatives recorded on our balance sheet under ASC Topic 815 and short-term investments, 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 WGL. We value our derivative contracts based on an “in-exchange” premise, and 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. WGL did not have any Level 1 derivatives at June 30, 2016 or September 30, 2015 . 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. At June 30, 2016 and September 30, 2015 , 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, as well as our interest rate swaps. 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, annualized volatilities of natural gas prices, and electricity congestion 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. Our Risk Analysis and Mitigation (RA&M) Group determines the valuation policies and procedures. The RA&M Group reports to WGL’s Chief Financial Officer. In accordance with WGL’s valuation policy, we may utilize a variety of valuation methodologies to determine the fair value of Level 3 derivative contracts, including internally developed valuation inputs and pricing models. The prices used in our valuations are corroborated using multiple pricing sources, and we periodically conduct assessments to determine whether each valuation model is appropriate for its intended purpose. The RA&M Group also evaluates changes in fair value measurements on a daily basis. At June 30, 2016 and September 30, 2015 , 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 life of the contract; (iii) contracts valued using historical spot price volatility assumptions and (iv) valuations using indicative broker quotes for inactive market locations. The following tables set forth financial instruments recorded at fair value as of June 30, 2016 and September 30, 2015 , respectively. 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. WGL Holdings, Inc. Fair Value Measurements Under the Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Total At June 30, 2016 Assets Natural gas related derivatives $ — $ 51.4 $ 58.3 $ 109.7 Electricity related derivatives — 2.0 19.5 21.5 Total Assets $ — $ 53.4 $ 77.8 $ 131.2 Liabilities Natural gas related derivatives $ — $ (76.3 ) $ (298.8 ) $ (375.1 ) Electricity related derivatives — (1.4 ) (30.2 ) (31.6 ) Interest rate derivatives — (46.9 ) — (46.9 ) Total Liabilities $ — $ (124.6 ) $ (329.0 ) $ (453.6 ) At September 30, 2015 Assets Natural gas related derivatives $ — $ 22.7 $ 28.5 $ 51.2 Electricity related derivatives — 2.0 21.3 23.3 Total Assets $ — $ 24.7 $ 49.8 $ 74.5 Liabilities Natural gas related derivatives $ — $ (33.9 ) $ (338.2 ) $ (372.1 ) Electricity related derivatives — (2.7 ) (37.3 ) (40.0 ) Interest rate derivatives — (3.4 ) — (3.4 ) Total Liabilities $ — $ (40.0 ) $ (375.5 ) $ (415.5 ) Washington Gas Light Company Fair Value Measurements Under the Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Total At June 30, 2016 Assets Natural gas related derivatives $ — $ 15.7 $ 19.2 $ 34.9 Total Assets $ — $ 15.7 $ 19.2 $ 34.9 Liabilities Natural gas related derivatives $ — $ (25.1 ) $ (262.5 ) $ (287.6 ) Interest rate derivatives — (8.8 ) — (8.8 ) Total Liabilities $ — $ (33.9 ) $ (262.5 ) $ (296.4 ) At September 30, 2015 Assets Natural gas related derivatives $ — $ 6.9 $ 13.5 $ 20.4 Total Assets $ — $ 6.9 $ 13.5 $ 20.4 Liabilities Natural gas related derivatives $ — $ (11.6 ) $ (294.6 ) $ (306.2 ) Total Liabilities $ — $ (11.6 ) $ (294.6 ) $ (306.2 ) 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, by contract type, as of June 30, 2016 and September 30, 2015 . Quantitative Information about Level 3 Fair Value Measurements Net Fair Value Valuation Techniques Unobservable Inputs Range ($ In millions) WGL Holdings, Inc. Natural gas related derivatives $(240.5) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.060) - $3.815 Option Model Natural Gas Basis Price (per dekatherm) ($1.060) - $3.815 Annualized Volatility of Spot Market Natural Gas 25.0% - 915.6% Electricity related derivatives $(10.7) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($6.20) - $69.70 Washington Gas Light Company Natural gas related derivatives $(243.3) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.019) - $3.750 Net Fair Value ($ In millions) WGL Holdings, Inc. Natural gas related derivatives $(309.7) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.441) - $3.580 Option Model Natural Gas Basis Price (per dekatherm) ($1.283) - $2.950 Annualized Volatility of Spot Market Natural Gas 22.5% - 867.0% Electricity related derivatives $(16.0) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($5.75) - $73.35 Washington Gas Light Company Natural gas related derivatives $(281.1) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.441) - $3.500 The following tables are a summary of the changes in the fair value of our derivative instruments that are measured at net fair value on a recurring basis in accordance with ASC Topic 820 using significant Level 3 inputs during the three and nine months ended June 30, 2016 and 2015 , respectively. WGL Holdings, Inc. Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Total Three Months Ended June 30, 2016 Balance at April 1, 2016 $ (204.3 ) $ (30.5 ) $ (234.8 ) Realized and unrealized gains (losses) Recorded to income (8.9 ) 22.5 13.6 Recorded to regulatory assets—gas costs (27.6 ) — (27.6 ) Transfers into Level 3 0.1 — 0.1 Transfers out of Level 3 (0.2 ) — (0.2 ) Purchases — (10.7 ) (10.7 ) Settlements 0.4 8.0 8.4 Balance at June 30, 2016 $ (240.5 ) $ (10.7 ) $ (251.2 ) Three Months Ended June 30, 2015 Balance at April 1, 2015 $ (319.6 ) $ (10.5 ) $ (330.1 ) Realized and unrealized gains (losses) Recorded to income (33.6 ) (4.8 ) (38.4 ) Recorded to regulatory assets—gas costs (7.7 ) — (7.7 ) Transfers out of Level 3 3.9 — 3.9 Purchases — 3.9 3.9 Settlements 6.0 2.6 8.6 Balance at June 30, 2015 $ (351.0 ) $ (8.8 ) $ (359.8 ) Nine Months Ended June 30, 2016 Balance at October 1, 2015 $ (309.7 ) $ (16.0 ) $ (325.7 ) Realized and unrealized gains (losses) Recorded to income 34.6 (14.2 ) 20.4 Recorded to regulatory assets—gas costs 15.9 — 15.9 Transfers into Level 3 (0.8 ) — (0.8 ) Transfers out of Level 3 8.7 — 8.7 Purchases — (4.4 ) (4.4 ) Settlements 10.8 23.9 34.7 Balance at June 30, 2016 $ (240.5 ) $ (10.7 ) $ (251.2 ) Nine Months Ended June 30, 2015 Balance at October 1, 2014 $ (294.7 ) $ (5.0 ) $ (299.7 ) Realized and unrealized gains (losses) Recorded to income (51.0 ) (15.3 ) (66.3 ) Recorded to regulatory assets—gas costs (48.0 ) — (48.0 ) Transfers into Level 3 5.4 — 5.4 Transfers out of Level 3 3.6 — 3.6 Purchases — 7.3 7.3 Settlements 33.7 4.2 37.9 Balance at June 30, 2015 $ (351.0 ) $ (8.8 ) $ (359.8 ) Washington Gas Light Company Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs (In millions) Natural Gas Related Derivatives Three Months Ended June 30, 2016 Balance at April 1, 2016 $ (194.3 ) Realized and unrealized gains (losses) Recorded to income (21.6 ) Recorded to regulatory assets—gas costs (27.6 ) Settlements 0.2 Balance at June 30, 2016 $ (243.3 ) Three Months Ended June 30, 2015 Balance at April 1, 2015 $ (299.8 ) Realized and unrealized gains (losses) Recorded to income (7.6 ) Recorded to regulatory assets—gas costs (7.7 ) Transfers out of Level 3 2.8 Settlements 5.1 Balance at June 30, 2015 $ (307.2 ) Nine Months Ended June 30, 2016 Balance at October 1, 2015 $ (281.1 ) Realized and unrealized gains (losses) Recorded to income 3.3 Recorded to regulatory assets—gas costs 15.9 Transfers into Level 3 (0.2 ) Transfers out of Level 3 8.8 Settlements 10.0 Balance at June 30, 2016 $ (243.3 ) Nine Months Ended June 30, 2015 Balance at October 1, 2014 $ (270.6 ) Realized and unrealized gains (losses) Recorded to income (30.3 ) Recorded to regulatory assets—gas costs (48.0 ) Transfers into Level 3 5.4 Transfers out of Level 3 2.5 Settlements 33.8 Balance at June 30, 2015 $ (307.2 ) Transfers between different levels of the fair value hierarchy may occur based on fluctuations in the valuation and on the level of observable inputs used to value the instruments from period to period. It is our policy to show both transfers into and out of the different levels of the fair value hierarchy at the fair value as of the beginning of the period. Washington Gas did not have any transfers into or out of Level 3 during the three months ended June 30, 2016 . Transfers out of Level 3 during the three and nine months ended June 30, 2016 and 2015 were due to an increase in valuations using observable market inputs. Transfers into Level 3 during the three and nine months ended June 30, 2016 and 2015 were due to an increase in unobservable market inputs used in valuations. The table below sets forth the line items on the statements of income to which amounts are recorded for the three and nine months ended June 30, 2016 and 2015 , respectively, related to fair value measurements using significant Level 3 inputs. WGL Holdings, Inc. Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Total Three Months Ended June 30, 2016 Operating revenues—non-utility $ 6.5 $ (17.4 ) $ (10.9 ) Utility cost of gas (21.6 ) — (21.6 ) Non-utility cost of energy-related sales 6.2 39.9 46.1 Total $ (8.9 ) $ 22.5 $ 13.6 Three Months Ended June 30, 2015 Operating revenues—non-utility $ (22.3 ) $ (3.0 ) $ (25.3 ) Utility cost of gas (7.6 ) — (7.6 ) Non-utility cost of energy-related sales (3.7 ) (1.8 ) (5.5 ) Total $ (33.6 ) $ (4.8 ) $ (38.4 ) Nine Months Ended June 30, 2016 Operating revenues—non-utility $ 22.5 $ (25.9 ) $ (3.4 ) Utility cost of gas 3.3 — 3.3 Non-utility cost of energy-related sales 8.8 11.7 20.5 Total $ 34.6 $ (14.2 ) $ 20.4 Nine Months Ended June 30, 2015 Operating revenues—non-utility $ (20.7 ) $ 21.0 $ 0.3 Utility cost of gas (30.3 ) — (30.3 ) Non-utility cost of energy-related sales — (36.3 ) (36.3 ) Total $ (51.0 ) $ (15.3 ) $ (66.3 ) Washington Gas Light Company Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements (In millions) Natural Gas Related Derivatives Three Months Ended June 30, 2016 Utility cost of gas $ (21.6 ) Total $ (21.6 ) Three Months Ended June 30, 2015 Utility cost of gas $ (7.6 ) Total $ (7.6 ) Nine Months Ended June 30, 2016 Utility cost of gas $ 3.3 Total $ 3.3 Nine Months Ended June 30, 2015 Utility cost of gas $ (30.3 ) Total $ (30.3 ) Unrealized gains (losses) attributable to derivative assets and liabilities measured using significant Level 3 inputs were recorded as follows, for the three and nine months ended June 30, 2016 and 2015 , respectively. WGL Holdings, Inc. Unrealized Gains (Losses) Recorded for Level 3 Measurements (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Total Three Months Ended June 30, 2016 Recorded to income Operating revenues—non-utility $ 6.7 $ (10.3 ) $ (3.6 ) Utility cost of gas (22.2 ) — (22.2 ) Non-utility cost of energy-related sales 5.2 33.2 38.4 Recorded to regulatory assets—gas costs (28.9 ) — (28.9 ) Total $ (39.2 ) $ 22.9 $ (16.3 ) Three Months Ended June 30, 2015 Recorded to income Operating revenues—non-utility $ (21.3 ) $ 0.8 $ (20.5 ) Utility cost of gas (1.8 ) — (1.8 ) Non-utility cost of energy-related sales (5.6 ) 2.5 (3.1 ) Recorded to regulatory assets—gas costs (9.2 ) — (9.2 ) Total $ (37.9 ) $ 3.3 $ (34.6 ) Nine Months Ended June 30, 2016 Recorded to income Operating revenues—non-utility $ 26.1 $ (6.7 ) $ 19.4 Utility cost of gas (0.2 ) — (0.2 ) Non-utility cost of energy-related sales 2.6 15.1 17.7 Recorded to regulatory assets—gas costs 9.2 — 9.2 Total $ 37.7 $ 8.4 $ 46.1 Nine Months Ended June 30, 2015 Recorded to income Operating revenues—non-utility $ (17.6 ) $ 21.7 $ 4.1 Utility cost of gas (23.1 ) — (23.1 ) Non-utility cost of energy-related sales (1.7 ) (31.5 ) (33.2 ) Recorded to regulatory assets—gas costs (38.1 ) — (38.1 ) Total $ (80.5 ) $ (9.8 ) $ (90.3 ) Washington Gas Light Company Unrealized Gains (Losses) Recorded for Level 3 Measurements (In millions) Natural Gas Related Derivatives Three Months Ended June 30, 2016 Recorded to income - utility cost of gas $ (22.2 ) Recorded to regulatory assets—gas costs (28.9 ) Total $ (51.1 ) Three Months Ended June 30, 2015 Recorded to income - utility cost of gas $ (1.8 ) Recorded to regulatory assets—gas costs (9.2 ) Total $ (11.0 ) Nine Months Ended June 30, 2016 Recorded to income - utility cost of gas $ (0.2 ) Recorded to regulatory assets—gas costs 9.2 Total $ 9.0 Nine Months Ended June 30, 2015 Recorded to income - utility cost of gas $ (23.1 ) Recorded to regulatory assets—gas costs (38.1 ) Total $ (61.2 ) The following table presents the carrying amounts and estimated fair values of our financial instruments at June 30, 2016 and September 30, 2015 . WGL Holdings, Inc. Fair Value of Financial Instruments June 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 20.5 $ 20.5 $ 11.0 $ 11.0 Other short-term investments (a) $ 0.1 $ 0.1 $ 0.4 $ 0.4 Commercial paper (b) $ 306.0 $ 306.0 $ 332.0 $ 332.0 Project financing (b) $ 52.3 $ 52.3 $ — $ — Long-term debt (c) $ 1,194.3 $ 1,373.1 $ 944.2 $ 1,057.9 Washington Gas Light Company Fair Value of Financial Instruments June 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 4.0 $ 4.0 $ 4.3 $ 4.3 Other short-term investments (a) $ 0.1 $ 0.1 $ 0.4 $ 0.4 Commercial paper (b) $ 150.0 $ 150.0 $ 89.0 $ 89.0 Project financing (b) $ 52.3 $ 52.3 $ — $ — Long-term debt (c) $ 695.9 $ 868.2 $ 695.9 $ 811.9 (a) Balance is located in cash and cash equivalents in the accompanying balance sheets. These amounts may be offset by outstanding checks. (b) Balance is located in notes payable in the accompanying balance sheets. (c) Includes adjustments for current maturities and unamortized discounts, as applicable. Our money market funds are Level 1 valuations and their carrying amount approximates fair value. Other short-term investments are primarily overnight investment accounts; their carrying amount approximates fair value based on Level 2 inputs. The maturity of our commercial paper outstanding at both June 30, 2016 and September 30, 2015 is under 30 days. Due to the short term nature of these notes, the carrying cost of our commercial paper approximates fair value using Level 2 inputs. Due to the short term nature of our project financing arrangements, the carrying cost approximates fair value using Level 2 inputs. Neither WGL’s nor Washington Gas’ long-term debt is actively traded. The fair value of long-term debt was estimated based on the quoted market prices of the U.S. Treasury issues having a similar term to maturity, adjusted for the credit quality of the debt issuer, WGL or Washington Gas. Our long-term debt fair value measurement is classified as Level 3. Non Recurring Basis During the nine months ended June 30, 2016 , WGSW recognized a loss of $3.0 million associated with the impairment of its investment in direct financing leases from Nextility. The investment in direct financing leases is currently valued at $2.2 million , net of unamortized tax credits. We measured the impairment as the amount by which the carrying value exceeded the estimated fair value of the related collateral. The fair value was calculated based on the discounted cash flows estimated over the remaining asset life. The fair value of this investment was a Level 3 measurement. During the nine months ended June 30, 2015 , Washington Gas Resources recorded an impairment charge on its investment in ASDHI to its fair value using the income approach. The amount of the impairment was equivalent to the amount of the carrying value of $5.6 million and was due to management’s assumption of the current valuation and expected return from the investment. The fair value of this investment was a Level 3 measurement.

Operating Segment Reporting

Operating Segment Reporting	9 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Operating Segment Reporting	OPERATING SEGMENT REPORTING We have four reportable operating segments: regulated utility, retail energy-marketing, commercial energy systems and midstream energy services. The division of these segments into separate revenue generating components is based upon regulation, products and services. Our chief operating decision maker is our Chief Executive Officer and we evaluate segment performance based on Earnings Before Interest and Taxes (EBIT). EBIT is defined as earnings before interest and taxes from continuing operations. Items we do not include in EBIT are interest expense, intercompany financing activity, dividends on Washington Gas preferred stock, and income taxes. EBIT includes transactions between reportable segments. We also evaluate our operating segments based on other relevant factors, such as penetration into their respective markets and return on equity. Our four segments are summarized below. • Regulated Utility – The regulated utility segment is our core business. It consists of Washington Gas and Hampshire. Washington Gas provides regulated gas distribution services (including the sale and delivery of natural gas) to end use customers and natural gas transportation services to an unaffiliated natural gas distribution company in West Virginia under a Federal Energy Regulatory Commission (FERC) approved interstate transportation service operating agreement. Hampshire provides regulated interstate natural gas storage services to Washington Gas under a FERC approved interstate storage service tariff. • Retail Energy-Marketing – The retail energy-marketing segment consists of WGL Energy Services, which sells natural gas and electricity directly to retail customers in competition with regulated utilities and unregulated gas and electricity marketers. • Commercial Energy Systems – The commercial energy systems segment consists of WGL Energy Systems which provides clean and energy efficient solutions including commercial solar, energy efficiency and combined heat and power projects and other distributed generation solutions to government and commercial clients. In addition, this segment comprises the operations of WGSW, a holding company formed to invest in alternative energy assets. • Midstream Energy Services – The midstream energy services segment consists of WGL Midstream, which engages in acquiring, investing in, managing and optimizing natural gas storage and transportation assets. Administrative and business development activity costs associated with WGL and Washington Gas Resources and activities and transactions that are not significant enough on a stand-alone basis to warrant treatment as an operating segment, and that do not fit into one of our four operating segments, are aggregated as “Other Activities” in the Operating Segment Financial Information presented below. The following tables present operating segment information for the three and nine months ended June 30, 2016 and 2015 . Operating Segment Financial Information (In thousands) Operating Revenues (a) Depreciation and Amortization Equity in EBIT Total Assets Capital Expenditures Equity Method Investments Three Months Ended June 30, 2016 Regulated utility $ 187,077 $ 29,632 $ — $ (20,458 ) $ 4,467,449 $ 106,773 $ — Retail energy-marketing 266,214 233 — 49,544 484,511 768 — Commercial energy systems 20,842 3,900 2,162 8,286 787,248 34,125 65,289 Midstream energy services (17,989 ) 26 2,365 (16,908 ) 433,395 — 217,491 Other activities — — — (517 ) 201,354 — — Eliminations (b) (15,557 ) (5 ) — 178 (631,144 ) — — Total consolidated $ 440,587 $ 33,786 $ 4,527 $ 20,125 $ 5,742,813 $ 141,666 $ 282,780 Three Months Ended June 30, 2015 Regulated utility $ 190,345 $ 27,740 $ — $ (6,262 ) $ 4,095,646 $ 75,413 $ — Retail energy-marketing 268,249 151 — 16,654 458,745 — — Commercial energy systems 14,674 2,787 544 3,750 611,380 27,271 64,323 Midstream energy services (25,801 ) 31 718 (26,607 ) 196,770 85 56,967 Other activities — — — (970 ) 106,861 — — Eliminations (b) (6,294 ) (13 ) — (541 ) (492,362 ) — — Total consolidated $ 441,173 $ 30,696 $ 1,262 $ (13,976 ) $ 4,977,040 $ 102,769 $ 121,290 Nine Months Ended June 30, 2016 Regulated utility $ 934,347 $ 86,318 $ — $ 243,102 $ 4,467,449 $ 267,230 $ — Retail energy-marketing 925,180 872 — 52,055 484,511 7,595 — Commercial energy systems 57,066 11,105 5,554 10,251 787,248 73,769 65,289 Midstream energy services 16,223 97 5,004 17,631 433,395 — 217,491 Other activities — — — (2,773 ) 201,354 — — Eliminations (b) (43,156 ) (24 ) — (416 ) (631,144 ) — — Total consolidated $ 1,889,660 $ 98,368 $ 10,558 $ 319,850 $ 5,742,813 $ 348,594 $ 282,780 Nine Months Ended June 30, 2015 Regulated utility $ 1,193,232 $ 81,958 $ — $ 238,645 $ 4,095,646 $ 235,707 $ — Retail energy-marketing 1,003,339 470 — 39,185 458,745 5 — Commercial energy systems 35,745 7,693 1,623 4,731 611,380 81,246 64,323 Midstream energy services (17,997 ) 93 1,865 (23,343 ) 196,770 85 56,967 Other activities — — 750 (8,915 ) 106,861 — — Eliminations (b) (22,176 ) (55 ) — (592 ) (492,362 ) — — Total consolidated $ 2,192,143 $ 90,159 $ 4,238 $ 249,711 $ 4,977,040 $ 317,043 $ 121,290 (a) Operating revenues are reported gross of revenue taxes. Operating revenue amounts in the “Eliminations” row represent total intersegment revenues associated with sales from the regulated utility segment to the retail energy-marketing segment. Midstream Energy Services’ cost of energy related sales is netted with its gross revenues. (b) Eliminations include any trading activities, including mark-to market valuations, between WGL Midstream and WGL Energy Services, project financing intercompany loans and a timing difference between Commercial Energy Systems’ recognition of revenue for the sale of Renewable Energy Credits (RECs) to Retail Energy-Marketing and Retail Energy-Marketing’s recognition of the associated expense. Retail Energy-Marketing has recorded a portion of the REC’s purchased as inventory to be used in future periods at which time they will be expensed. The following table provides a reconciliation from EBIT to net income applicable to common stock. Three Months Ended June 30, Nine Months Ended June 30, (In thousands) 2016 2015 2016 2015 Total consolidated EBIT $ 20,125 $ (13,976 ) $ 319,850 $ 249,711 Interest expense 12,998 13,140 38,757 38,704 Income (loss) before income taxes 7,127 (27,116 ) 281,093 211,007 Income tax expense (benefit) 4,772 (11,756 ) 103,619 80,364 Net income (loss) 2,355 (15,360 ) 177,474 130,643 Dividends on Washington Gas Light Company preferred stock 330 330 990 990 Net income (loss) applicable to common stock $ 2,025 $ (15,690 ) $ 176,484 $ 129,653

Other Investments

Other Investments	9 Months Ended
	Jun. 30, 2016
Other Investments [Abstract]
Other Investments	OTHER INVESTMENTS When determining how to account for our interests in other legal entities, WGL first evaluates if we are required to apply the variable interest entity (VIE) model of accounting to the entity. If the VIE model is not applicable, the entity is evaluated under the voting interest model. Under the VIE model, we have a controlling financial interest in a VIE (i.e. are the primary beneficiary) when we have current or potential rights that give us the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance combined with a variable interest that gives us the right to receive potentially significant benefits or the obligation to absorb potentially significant losses. When changes occur to the design of an entity, we reconsider whether it is subject to the VIE model. We continuously evaluate whether we have a controlling financial interest in a VIE. Under the voting interest model, we generally have a controlling financial interest in an entity where we currently hold, directly or indirectly, more than 50% of the voting rights or where we exercise control through substantive participating rights. However, we consider substantive rights held by other partners in determining if we hold a controlling financial interest, and in some cases, despite owning more than 50% of the common stock of an investee, an evaluation of our rights results in the determination that we do not have a controlling financial interest. We reevaluate whether we have a controlling financial interest in these entities when our voting or substantive participating rights change. Unconsolidated affiliates are unconsolidated VIEs and other entities evaluated under the voting interest method in which we do not have a controlling financial interest, but over which we have varying degrees of influence. Where we have significant influence, the affiliates are accounted for as equity method investments. Where we do not have significant influence, the affiliates are accounted for under the cost method. Investments in, and advances to, affiliated companies are presented in the caption “Investments in unconsolidated affiliates” in the accompanying Consolidated Balance Sheets. WGL uses the Hypothetical Liquidation at Book Value (HLBV) methodology for certain equity method investments when the capital structure of the equity investment results in different liquidation rights and priorities than what is reflected by the underlying percentage ownership interests as defined by an equity investment agreement. For investments accounted for under the HLBV method, simply applying the percentage ownership interest to GAAP net income in order to determine earnings or losses does not accurately represent the income allocation and cash flow distributions that will ultimately be received by the investors. The equity investment agreements for ASD Solar, LP (ASD), Meade Pipeline Co LLC (Meade), Mountain Valley Pipeline, LLC (Mountain Valley) and Stonewall Gas Gathering System (Stonewall System) have liquidation rights and priorities that are sufficiently different from the ownership percentages that the HLBV method was deemed appropriate. The calculation may vary in its complexity depending on the capital structure and the tax considerations for the investments. WGL applies HLBV using a balance sheet approach. When applying HLBV, WGL determines the amount that it would receive if an equity investment entity were to liquidate all of its assets at book value (as valued in accordance with GAAP) and distribute that cash to the investors based on the contractually defined liquidation priorities. The change in WGL's claim on the investee's book value at the beginning and end of the reporting period (adjusted for contributions and distributions) is WGL’s share of the earnings or losses from the equity investment for the period. Variable Interest Entities WGL has a variable interest in four investments that qualify as VIEs: • Meade, • SunEdison, • Nextility, and • ASD. At June 30, 2016 , WGL and its subsidiaries are not the primary beneficiary for any of the above VIEs, therefore we have not consolidated any of the VIE entities. The nature of WGL’s involvement with these investments lacks the characteristics of a controlling financial interest. WGL either does not have control over any of the VIEs’ activities that are economically significant to the VIEs and/or WGL does not have the obligation to absorb expected losses or the right to receive expected gains that could be significant to the VIE. Meade In 2014, WGL through its subsidiary WGL Midstream, entered into a limited liability company agreement and formed Meade, a Delaware limited liability company to partner with Transcontinental Gas Pipe Line Company, LLC (Williams) to invest in a regulated pipeline project called Central Penn Pipeline (Central Penn). Central Penn will be an approximately 185 -mile pipeline originating in Susquehanna County, Pennsylvania and extending to Lancaster County, Pennsylvania that will have the capacity to transport and deliver up to approximately 1.7 million dekatherms per day of natural gas. WGL Midstream plans to invest an estimated $410.0 million for a 55% interest in Meade. Although WGL Midstream holds greater than a 50% interest in Meade, Meade is accounted for under the equity method of accounting because WGL Midstream does not have the power to direct the activities most significant to the economic performance of Meade. Meade is accounted for under the HLBV equity method of accounting, and any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statements of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. At June 30, 2016 and September 30, 2015 , WGL Midstream held a $68.1 million and $30.5 million , respectively, equity method investment in Meade. WGL Midstream's maximum financial exposure is limited to its contributions made to the partnership, which were $68.4 million at June 30, 2016 . SunEdison and Nextility WGSW is party to two agreements to fund residential and commercial retail solar energy installations with two separate companies. WGSW has master purchase agreements and master lease agreements with SunEdison, Inc. (SunEdison) and with Nextility, Inc. (Nextility) for sale/leaseback arrangements for residential and commercial solar systems. Our agreements with SunEdison and Nextility are accounted for as direct financing leases. WGSW records associated interests in the financing leases in “Other income (expenses)-net” line in the accompanying Consolidated Statements of Income. WGSW held a $32.5 million and $37.2 million combined investment in direct financing leases at June 30, 2016 and September 30, 2015 , respectively, of which $1.2 million and $2.0 million are current receivables recorded in “Accounts Receivable” in the accompanying Consolidated Balance Sheets at June 30, 2016 and September 30, 2015 , respectively. Additionally, we had balances of $14.0 million and $14.7 million of unamortized tax credits related to these investments in "Unamortized investment tax credits" on the accompanying Consolidated Balance Sheets at June 30, 2016 and September 30, 2015 , respectively. Minimum future lease payments receivable under direct financing leases over the next five fiscal years and thereafter are as follows: Minimum Payments Receivable for Direct Financing Leases (In millions) Remainder of 2016 $ 0.7 2017 2.2 2018 2.2 2019 2.1 2020 2.2 Thereafter 30.7 Total $ 40.1 Minimum payments receivable exclude $9.7 million of residual values and $4.4 million in tax related items. Associated with these investments, WGSW holds $18.7 million of unearned income and $ 3.0 million of impairment charges for Nextility on its balance sheet. The initial direct costs (incurred in FY 2012) associated with these investments was $0.7 million . Our maximum financial exposure from solar agreements is limited to WGSW's lease payment receivables and investment contributions made to these companies. On a quarterly basis, we review our direct financing leases for credit losses. Our review is based on multiple factors including historical losses, if any, economic factors currently impacting our counterparties' repayment ability, and other factors relevant to the business such as changes to regulatory and tax incentives. Our exposure is offset by the owned physical assets received as part of the transaction and the quick economic return for the investment through the investment tax credit/treasury grant proceeds and accelerated depreciation. In April 2016, Nextility requested a restructuring of its direct financing lease arrangement with WGSW because Nextility was not collecting sufficient revenues related to the underlying thermal solar projects covered by the amended master lease agreement. Utilizing information available at March 31, 2016, WGSW determined that a $3.0 million impairment of the Nextility investment in direct financing leases was appropriate. Depending on the future performance of these projects, there could be an additional impairment of our remaining investment balance of $ 2.2 million , net of unamortized investment tax credits. As of June 30, 2016, WGSW is negotiating with Nextility for a resolution of this matter. On April 21, 2016, SunEdison filed a voluntary petition with the United States Bankruptcy Court for relief under Title 11 of the United States Code. EchoFirst Finance Company LLC, the subsidiary of SunEdison that is the party to our master purchase and lease agreements, is not a debtor in this bankruptcy proceeding. We will continue to monitor the impact of this development on our investment. ASD WGSW is also a limited partner in ASD, a limited partnership formed to own and operate a portfolio of residential solar projects, primarily rooftop photovoltaic power generation systems. As a limited partner, WGSW provided funding to the partnership but does not have power to direct the activities that most significantly affect the operations and economic performance of the entity. In January 2014, the funding commitment period expired for the partnership. WGSW’s maximum financial exposure is limited to its contributions made to the partnership, which were $72.6 million at June 30, 2016. Our investment in ASD is accounted for under the HLBV equity method of accounting; any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statements of Income and are added to or subtracted from the carrying amount of WGSW’s investment balance. At June 30, 2016 and September 30, 2015 , WGSW held a $65.3 million and $63.5 million , respectively, equity method investment in ASD. ASD is consolidated by the general partner, Solar Direct LLC. Solar Direct LLC is a wholly owned subsidiary of American Solar Direct Inc. (ASDI). At June 30, 2016 , the carrying amount of WGSW’s investment in ASD exceeded the amount of the underlying equity in net assets by $35.8 million due to WGSW recording additions to its investment in ASD’s net assets at fair value of contributions in accordance with GAAP. This basis difference is being amortized over the life of the assets. Non-VIE Investments ASDHI At September 30, 2014 , Washington Gas Resources held a $5.6 million investment in American Solar Direct Holdings Inc. (ASDHI) consisting of warrants and preferred stock. During the nine months ended June 30, 2015 , Washington Gas Resources impaired its entire investment in ASDHI by its carrying value of $5.6 million based on management's assumption of the current valuation and expected return from the investment. Constitution In 2013, WGL Midstream invested in Constitution Pipeline Company, LLC (Constitution). At June 30, 2016 , WGL Midstream's total share of the cost of Constitution is estimated to be $95.5 million , over the term of the agreement, reflecting a 10% share in the pipeline venture. This natural gas pipeline venture is designed to transport natural gas from the Marcellus region in northern Pennsylvania to major northeastern markets. Constitution is accounted for under the equity method of accounting; any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statements of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. The equity method is considered appropriate because Constitution is an LLC with specific ownership accounts and ownership between five and fifty percent resulting in WGL Midstream maintaining a more than minor influence over the partnership operating and financing policies. O n April 22, 2016, the New York State Department of Environmental Conservation (NYSDEC) denied Constitution's application for a Section 401 Water Quality Certification (Section 401 Certification) for the pipeline, which is necessary for the construction and operation of the pipeline. Constitution has stated that it remains committed to pursuing the project and that it intends to pursue all available options to challenge the legality and appropriateness of NYSDEC’s decision. In May, 2016, Constitution filed actions in the U.S. Circuit Court of Appeals for the Second Circuit and the U.S. District Court for the Northern District of New York, respectively, appealing the decision and a seeking declaratory judgment that the State of New York’s permitting authority is preempted by federal law. The courts have granted Constitution's motions to expedite the schedules for these legal actions. In light of the forgoing matters, Constitution has revised its target in-service date to the second half of 2018. We can give no assurance, however, that Constitution’s efforts to obtain the Section 401 Certification will be successful. At June 30, 2016, we held a $ 39.9 million equity method investment in Constitution. We have evaluated our investment in Constitution for other than temporary impairment as of June 30, 2016. Our impairment assessment used income and market approaches in determining the fair value of our investment in Constitution, including consideration of the severity and duration of any decline in fair value of our investment in the project. Our key inputs included, but are not limited to, significant management judgments and estimates, including projections of the project’s cash flows, selection of a discount rate, market multipliers and probability weighting of potential outcomes of legal and regulatory proceedings. At this time, we do not have an other than temporary impairment and have not recorded any impairment charge to reduce the carrying value of our investment. Further developments or indicators of an unfavorable resolution, however, may require a future impairment of this investment including, if Constitution is ultimately unable to obtain the Section 401 Certification, an impairment charge of substantially all of our investment in the capitalized project costs. It is also possible that Constitution could incur certain supplier-related costs in the event of a prolonged delay or termination of the project. We will continue to monitor and update our impairment analysis as required. Mountain Valley In March 2015, WGL Midstream acquired a 7% equity interest in Mountain Valley Pipeline, LLC (Mountain Valley). The proposed pipeline to be developed, constructed, owned and operated by Mountain Valley, will transport approximately 2.0 million dekatherms of natural gas per day from interconnects with EQT Corporation's Equitrans system, near the MarkWest Mobley plant in West Virginia to Transcontinental Gas Pipe Line Company LLC's Station 165 in Pittsylvania County, Virginia. WGL Midstream expects to invest through scheduled capital contributions through the in-service date of the pipeline, its pro rata share (based on its 7% equity interest) of project costs, an estimated aggregate amount of approximately $228.0 million. WGL Midstream held a $16.7 million equity method investment in Mountain Valley at June 30, 2016 . The equity method is considered appropriate because Mountain Valley is an LLC with specific ownership accounts and ownership between five and fifty percent resulting in WGL Midstream maintaining a more than minor influence over the partnership operating and financing policies. The investment in MVP is accounted for under the HLBV equity method of accounting. At June 30, 2016 , WGL Midstream had a $14.0 million minimum funding requirement related to Mountain Valley and a $6.0 million guarantee on behalf of one of the other partners. In addition, WGL Midstream entered into an agreement to finance capital commitments as they are made by one of the other partners in the venture for an estimated aggregate amount of approximately $97.9 million, which represents the estimated total funding requirements for that partner's 3% ownership interest in the joint venture, inclusive of the minimum funding requirement. WGL Midstream has provided funding of $6.8 million as of June 30, 2016 related to this agreement. Stonewall System In February 2016, WGL Midstream acquired a 35% equity interest in an entity that owns and operates certain assets known as the Stonewall Gas Gathering System (the Stonewall System). WGL Midstream paid $89.4 million to acquire the equity interest pursuant to an option that WGL Midstream previously acquired. The Stonewall System has the capacity to gather up to 1.4 billion cubic feet of natural gas per day from the Marcellus production region in West Virginia, and connects with an interstate pipeline system that serves markets in the mid-Atlantic region. WGL Midstream held a $92.8 million equity method investment in the Stonewall System at June 30, 2016 . The equity method is considered appropriate because the Stonewall Gas Gathering is an LLC with specific ownership accounts and ownership between five and fifty percent resulting in WGL Midstream maintaining a more than minor influence over the partnership operating and financing policies. In May 2016, another party to the deal exercised its option and invested in the Stonewall System. As a result WGL Midstream's ownership decreased to 30% . The carrying amount of WGL Midstream's investment in the Stonewall System exceeded the amount of the underlying equity in net assets by $9.1 million that is being amortized over the life of the assets. The investment in Stonewall System is accounted for under the HLBV equity method of accounting. The balance sheet location of the investments discussed in this footnote at June 30, 2016 and September 30, 2015 are as follows: WGL Holdings, Inc. Balance Sheet Location of Other Investments As of June 30, 2016 (In millions) VIEs Non-VIEs Total Assets Investments in unconsolidated affiliates $ 133.4 $ 149.4 $ 282.8 Investments in direct financing leases, capital leases 31.3 — 31.3 Accounts receivable 1.2 6.8 (a) 8.0 Total assets $ 165.9 $ 156.2 $ 322.1 As of September 30, 2015 (In millions) Assets Investments in unconsolidated affiliates $ 94.0 $ 42.9 $ 136.9 Investments in direct financing leases, capital leases 35.2 — 35.2 Accounts receivable 2.0 4.2 (a) 6.2 Total assets $ 131.2 $ 47.1 $ 178.3 (a) Represents the financing provided to another partner in Mountain Valley to fund its capital commitment. Acquired ownership interest represents the collateral for repayment of the financing. The income statement location of the investments discussed in this footnote for the three and nine months ended June 30, 2016 and 2015 are as follows: WGL Holdings, Inc. Income Statement Location of Other Investments Three Months Ended June 30, 2016 Nine Months Ended June 30, 2016 (In millions) VIEs Non-VIEs Total VIEs Non-VIEs Total Equity in earnings of unconsolidated affiliates $ 2.2 $ 2.4 $ 4.6 $ 5.5 $ 5.1 $ 10.6 Depreciation and amortization — — — 0.2 — 0.2 Operations and maintenance — — — 3.0 — 3.0 Other income (expense) —net 0.8 — 0.8 2.4 (0.1 ) 2.3 Net income $ 3.0 $ 2.4 $ 5.4 $ 4.7 $ 5.0 $ 9.7 Three Months Ended June 30, 2015 Nine Months Ended June 30, 2015 Equity in earnings of unconsolidated affiliates $ 0.8 $ 0.5 $ 1.3 $ 2.4 $ 1.8 $ 4.2 Depreciation and amortization 0.1 — 0.1 0.2 — 0.2 Other income (expenses)—net 1.0 — 1.0 2.4 (5.6 ) (3.2 ) Net income (loss) $ 1.7 $ 0.5 $ 2.2 $ 4.6 $ (3.8 ) $ 0.8

Related Party Transactions

Related Party Transactions	9 Months Ended
	Jun. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS WGL and its subsidiaries engage in transactions in the ordinary course of business. Inter-company transactions and balances have been eliminated from the consolidated financial statements of WGL, except as described below. Washington Gas provides accounting, treasury, legal and other administrative and general support to affiliates, and files consolidated tax returns that include affiliated taxable transactions. Washington Gas bills its affiliates in accordance with regulatory requirements for the actual cost of providing these services, which approximates their market value. To the extent such billings are not paid, 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. In connection with billing for unregulated third party marketers, including WGL Energy Services, and with other miscellaneous billing processes, Washington Gas collects cash on behalf of affiliates and transfers the cash in a reasonable time period. Cash collected by Washington Gas on behalf of its affiliates but not transferred is recorded in “Payables to associated companies” on Washington Gas’ balance sheets. Washington Gas obtains third-party project financing on behalf of the Federal government to provide funds during the construction of certain energy management services projects entered into under Washington Gas' area-wide contract. In connection with work completed under the area-wide contract, the construction work is performed by WGL Energy Systems on behalf of Washington Gas and an amount is recorded in “Payables to associated companies” for work performed by WGL Energy Systems for which cash has not been transferred. Refer to Note 3— Short Term Debt for further discussion of the project financing. The following table presents the receivables and payables from associated companies as of June 30, 2016 and September 30, 2015 . Washington Gas Receivables / Payables from Associated Companies (In millions) June 30, 2016 September 30, 2015 Receivables from Associated Companies $ 11.5 $ 3.2 Payables to Associated Companies $ 73.1 $ 68.6 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 for these balancing services pursuant to tariffs approved by the appropriate regulatory bodies. These related party amounts related to balancing services provided to WGL Energy Services have been eliminated in the consolidated financial statements of WGL. The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Washington Gas - Gas Balancing Service Charges Three Months Ended June 30, Nine Months Ended June 30, (In millions) 2016 2015 2016 2015 Gas balancing service charge $ 5.5 $ 5.3 $ 21.7 $ 19.8 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. WGL Energy Services recognized accounts payable to Washington Gas of $4.9 million and $0.5 million at June 30, 2016 and September 30, 2015 , respectively, related to an imbalance in gas volumes. Due to regulatory treatment, these payables and receivables are not eliminated in the consolidated financial statements of WGL. Refer to Note 1— Accounting Policies of the Notes to Consolidated Financial Statements of the combined Annual Report on Form 10-K for the fiscal year ended September 30, 2015 for further discussion of these imbalance transactions. Washington Gas participates in a Purchase of Receivables (POR) program as approved by the Public Service Commission of Maryland (PSC of MD), whereby it purchases receivables from participating energy marketers at approved discount rates. In addition, WGL Energy Services participates in POR programs with certain Maryland and Pennsylvania utilities, whereby it sells its receivables to various utilities, including Washington Gas, at approved discount rates. The receivables purchased by Washington Gas are included in “Accounts receivable” in the accompanying balance sheet. Any activity between Washington Gas and WGL Energy Services related to the POR program has been eliminated in the accompanying financial statements for WGL. At June 30, 2016 and September 30, 2015 , Washington Gas had balances of $12.7 million and $6.6 million , respectively, of purchased receivables from WGL Energy Services. On April 1, 2016 Washington Gas transferred WSS and ESS storage assets to WGL Midstream through a permanent release. Washington Gas held a base gas option associated with the WSS storage facility which gave Washington Gas the right to purchase 723,706 dekatherms of base gas at either: (i) the end of its service with WSS or (ii) the permanent release of its WSS storage capacity, for $ 0.594 per dekatherm. The option was transferred from Washington Gas to WGL Midstream in an equity transfer through WGL, concurrent with the transfer of storage assets. At June 30, 2016, Washington Gas received cash of $ 0.9 million from WGL representing the value of the right to purchase base gas. This amount will be refunded to ratepayers through a credit to cost of gas. The effect of this equity transfer has been eliminated in the accompanying financial statements for WGL.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES REGULATORY CONTINGENCIES Certain legal and administrative proceedings incidental to our business, including regulatory contingencies, involve WGL and/or its subsidiaries. In our opinion, we have recorded an adequate provision for probable losses or refunds to customers for regulatory contingencies related to these proceedings. District of Columbia Jurisdiction Investigation into Washington Gas’ Cash Reimbursement to Competitive Service Providers (CSPs). On August 5, 2014, the Office of the People’s Counsel’s (OPC) of DC filed a complaint with the PSC of DC requesting that the Commission open an investigation into Washington Gas’ payments to CSPs to cash-out over-deliveries of natural gas supplies during the 2008-2009 winter heating season. OPC asserted that Washington Gas made excess payments in the amount of $ 2.4 million to CSPs. On December 19, 2014, the PSC of DC granted the OPC of DC’s request and opened a formal investigation. On October 27, 2015, the PSC of DC issued an order finding that Washington Gas, in performing the cash-out, had violated D.C. Code 34-1101’s requirement that no service shall be provided without Commission approval. The PSC of DC directed Washington Gas to provide calculations showing what the impact would have been had Washington Gas made volumetric adjustments to CSP deliveries as of April 2009, which Washington Gas calculates would result in a refund of approximately $ 2.4 million , which was recognized by WGL in fiscal year 2015. On February 3, 2016, the PSC of DC issued an order denying OPC’s application for reconsideration and granting in part, and denying in part, Washington Gas’ application for reconsideration. Washington Gas and OPC filed initial briefs on February 18, 2016, and reply briefs on February 29, 2016, on the issue of whether there is a more reasonable way to reconcile the over-deliveries by CSPs such as through volumetric adjustments or through cash payments. FINANCIAL GUARANTEES WGL has guaranteed payments primarily for certain commitments on behalf of certain subsidiaries. At June 30, 2016 , these guarantees totaled $30.6 million , $238.1 million , $11.5 million and $327.4 million for Washington Gas, WGL Energy Services, WGL Energy Systems and WGL Midstream, respectively. At June 30, 2016 , WGL also had guarantees on behalf of other subsidiaries totaling $2.0 million . The amount of such guarantees is periodically adjusted to reflect changes in the level of WGL's financial exposure related to these commitments. For all of our financial guarantees, WGL may cancel any or all future obligations upon written notice to the counterparty, but WGL would continue to be responsible for the obligations created under the guarantees prior to the effective date of the cancellation. WGL has also guaranteed payments for certain of our external partners. At June 30, 2016 , these guarantees totaled $18.9 million and the fair value of these guarantees was insignificant. ANTERO CONTRACT Washington Gas and WGL Midstream began purchasing natural gas on January 1, 2016, from Antero Resources Corporation (Antero) pursuant to certain natural gas purchase contracts. We purchase gas from Antero at invoiced prices based on an index specified in the contracts; however, contractual provisions allow either party to notify the other party if it believes the index price is no longer appropriate for the delivery point of the gas, and to trigger the negotiation of a new index price. If negotiations are unsuccessful, then the contract requires binding arbitration proceedings. When a new index price is determined under the contract, a "true up" of prior period invoices is required back to the date of initial notification. On November 16, 2015, due to significant changes to natural gas markets in and around the delivery point specified in the contracts, we provided notice to Antero invoking the provision requiring the negotiation of a new contractual index price. To date, negotiations have been unsuccessful and we are currently involved in arbitration proceedings to resolve this pricing dispute. Our Consolidated Financial Statements do not reflect the favorable effects of a change in the contractual index price. Through June 30, 2016, WGL Midstream has incurred approximately $ 8.8 million in losses associated with Antero’s use of the disputed index price.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefit Plans	9 Months Ended
	Jun. 30, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Pension and Other Post-Retirement Benefit Plans	PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS The following table shows the components of net periodic benefit costs (income) recognized in our financial statements during the three and nine months ended June 30, 2016 and 2015 . Components of Net Periodic Benefit Costs (Income) Three Months Ended June 30, 2016 2015 (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 3.6 $ 1.2 $ 3.9 $ 1.8 Interest cost 10.3 3.2 9.7 3.7 Expected return on plan assets (10.2 ) (5.1 ) (11.2 ) (5.2 ) Amortization of prior service cost (credit) — (4.4 ) 0.1 (3.8 ) Amortization of net actuarial loss 4.3 0.3 4.7 1.1 Net periodic benefit cost (income) 8.0 (4.8 ) 7.2 (2.4 ) Amount allocated to construction projects (1.5 ) 1.1 (1.2 ) 0.5 Amount deferred as regulatory asset/liability — net 1.8 (0.1 ) 1.8 (0.1 ) Amount charged (credited) to expense $ 8.3 $ (3.8 ) $ 7.8 $ (2.0 ) Nine Months Ended June 30, 2016 2015 Service cost $ 10.7 $ 3.4 $ 11.6 $ 5.3 Interest cost 31.0 9.8 29.3 11.0 Expected return on plan assets (30.7 ) (15.3 ) (33.5 ) (15.6 ) Amortization of prior service cost (credit) 0.2 (13.2 ) 0.2 (11.4 ) Amortization of net actuarial loss 12.7 0.9 14.1 3.3 Net periodic benefit cost (income) 23.9 (14.4 ) 21.7 (7.4 ) Amount allocated to construction projects (4.1 ) 3.0 (3.4 ) 1.5 Amount deferred as regulatory asset/liability — net 5.3 (0.2 ) 5.3 (0.2 ) Amount charged (credited) to expense $ 25.1 $ (11.6 ) $ 23.6 $ (6.1 ) Amounts included in the line item “Amount deferred as regulatory asset/liability-net,” as shown in the table above, represent the amortization of previously unrecovered costs of the applicable pension benefits or the health and life benefits as approved in the District of Columbia. These balances are being amortized over a five year period.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following tables show the changes in accumulated other comprehensive income (loss) for WGL and Washington Gas by component for the three and nine months ended June 30, 2016 and 2015 . WGL Holdings, Inc. Changes in Accumulated Other Comprehensive Loss by Component (In thousands) Three Months Ended June 30, Nine Months Ended June 30, 2016 2015 2016 2015 Beginning Balance $ (24,258 ) $ (11,643 ) $ (14,236 ) $ (7,961 ) Qualified cash flow hedging instruments (a) (16,995 ) 49 (34,545 ) (7,994 ) Amortization of net prior service credit (b) (216 ) (170 ) (644 ) (511 ) Amortization of net actuarial loss (b) 420 529 1,258 1,503 Current-period other comprehensive income (loss) (16,791 ) 408 (33,931 ) (7,002 ) Income tax expense (benefit) related to other comprehensive income (loss) (6,969 ) 163 (14,087 ) (3,565 ) Ending Balance $ (34,080 ) $ (11,398 ) $ (34,080 ) $ (11,398 ) (a) Cash flow hedging instruments represent interest rate swap agreements related to future debt issuances. Refer to Note 8- Derivative and Weather-related Instruments for further discussion of the interest rate swap agreements. (b) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14- Pension and other post-retirement benefit plans for additional details. Washington Gas Light Company Changes in Accumulated Other Comprehensive Loss by Component (In thousands) Three Months Ended June 30, Nine Months Ended June 30, 2016 2015 2016 2015 Beginning Balance $ (6,464 ) $ (6,031 ) $ (6,712 ) $ (6,413 ) Amortization of net prior service credit (a) (216 ) (170 ) (644 ) (511 ) Amortization of net actuarial loss (a) 420 529 1,258 1,503 Current-period other comprehensive income 204 359 614 992 Income tax expense related to other comprehensive income 82 143 244 394 Ending Balance $ (6,342 ) $ (5,815 ) $ (6,342 ) $ (5,815 ) (a) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14-Pension and other post-retirement benefit plans for additional details.

Environmental Matters

Environmental Matters	9 Months Ended
	Jun. 30, 2016
Environmental Remediation Obligations [Abstract]
Environmental Matters	ENVIRONMENTAL MATTERS Washington Gas has identified up to ten sites where it or its predecessors may have operated manufactured gas plants (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. Based on the information available to us, we have concluded that none of the sites are likely to present an unacceptable risk to human health or the environment, and either the appropriate remediation is being undertaken or Washington Gas believes no remediation is necessary. Washington Gas received a letter in February 2016, from the District of Columbia and National Park Service regarding the Anacostia River Sediment Project, indicating that the District is conducting a remedial investigation and feasibility study of the river to determine cleanup requirements and is preparing a natural resource damage assessment. The sediment project draft report identifies one of Washington Gas’ former MGP sites as a source of contaminants. Washington Gas is currently investigating potential contamination in the Anacostia River associated with this former MGP site under a consent decree with the District and federal governments. We are not able to estimate the amount of damages or timing associated with the government environmental investigation on the Anacostia River at this time.

Accounting Policies (Policies)

Accounting Policies (Policies)	9 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation WGL Holdings, Inc. (WGL) is a holding company that owns all of the shares of common stock of Washington Gas Light Company (Washington Gas), a regulated natural gas utility, and all of the shares of common stock of Washington Gas Resources Corporation (Washington Gas Resources) and Hampshire Gas Company (Hampshire). Washington Gas Resources owns all of the shares of common stock of four non-utility subsidiaries that include WGL Energy Services, Inc. (WGL Energy Services), WGL Energy Systems, Inc. (WGL Energy Systems), WGL Midstream, Inc. (WGL Midstream) and WGSW, Inc. (WGSW). Except where the content clearly indicates otherwise, “WGL,” “we,” “us” or “our” refers to the holding company or the consolidated entity of WGL Holdings, Inc. and all of its subsidiaries. Unless otherwise noted, these notes apply equally to WGL and Washington Gas. The condensed consolidated financial statements 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 consolidated financial statements and accompanying notes should be read in conjunction with the combined Annual Report on Form 10-K for WGL and Washington Gas for the fiscal year ended September 30, 2015 and the current report on Form 8-K filed on March 16, 2016, which amended the Annual Report on Form 10-K to recast the balance sheet for the October 1, 2015 adoption of ASU 2015-17, Income Taxes: Balance Sheet Classification of Deferred Taxes . Due to the seasonal nature of our businesses, the results of operations for the periods presented in this report are not necessarily indicative of actual results for the full fiscal years ending September 30, 2016 and 2015 , of either WGL or Washington Gas. The accompanying unaudited financial statements for WGL and Washington Gas reflect all normal recurring adjustments that are necessary, in our opinion, to present fairly the results of operations in accordance with GAAP. Prior period amounts related to deferred income tax assets and liabilities in the accompanying condensed balance sheets have been reclassified to conform to the current period presentation.
Impairment or Disposal of Long-Lived Assets	Impairments Management regularly reviews property and equipment and other long-lived assets, including certain definite-lived intangible assets and our equity method investments for possible impairment. For our equity and cost method investments, an impairment is recorded when the investment has experienced a decline in value that is other-than-temporary. Additionally, if the projects in which we hold an investment recognize an impairment loss, we would record our proportionate share of that impairment loss and evaluate the investment for decline in value that is other-than-temporary. This review occurs quarterly, or more frequently if events or changes in circumstances indicate the carrying amount of the asset may not be recoverable.
Storage Gas Valuation Methods	Storage Gas Valuation For Washington Gas and WGL Energy Services, storage gas inventories are accounted for using the first-in, first-out method. For WGL Midstream, storage gas inventory is accounted for using the weighted average cost method. Our inventory is stated at the lower-of-cost or market. Interim period inventory losses attributable to lower-of-cost or market adjustments may be reversed if the market value of the inventory is recovered by the end of the same fiscal year.
Accounting Standards Adopted Current Fiscal Year	ACCOUNTING STANDARDS ADOPTED IN FISCAL YEAR 2016 ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes The standard requires an entity to present deferred tax liabilities and assets as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets of a tax-paying component of an entity be offset by taxing jurisdiction and presented as a single amount remains the same. October 1, 2015 As a result of the standard, we have presented all deferred tax liabilities and assets, net, as non-current in "Deferred credits-Deferred income taxes" in the accompanying balance sheets, retrospectively for all periods presented. The adoption of this standard did not have a material effect on our financial statements. Refer to Note 7 — Income taxes , for further discussion of this standard.
New Accounting Pronouncements	OTHER NEWLY ISSUED ACCOUNTING STANDARDS ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments For credit losses on financial instruments, 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. October 1, 2020 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting This standard simplifies several aspects of the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and statutory tax withholding requirements. October 1, 2017 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2014-09, Revenue from Contracts with Customers (Topic 606), including subsequent ASUs clarifying the guidance. ASU 2014-09 establishes a comprehensive revenue recognition model clarifying the method used to determine the timing and requirements for revenue recognition from contracts with customers. The disclosure requirements under the new standard will enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-02, Leases (Topic 842) This standard requires recognition of a right-to-use asset and lease liability on the statement of financial position and disclosure of key information about leasing arrangements. The standard requires application using a modified retrospective approach. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. We may elect early adoption. ASU 2016-01, Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The new standard significantly revises an entity’s accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2015-03 and ASU 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost and Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements The standard requires an entity to present debt issuance costs in the balance sheet as a direct deduction of the debt liability in a manner consistent with its accounting treatment of debt discounts. The standard requires retrospective application. October 1, 2016 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis The standard changes the analysis to be performed in determining whether certain types of legal entities should be consolidated, specifically the analysis of limited partnerships and similar entities, fee arrangements and related party relationships. The standard permits prospective or retrospective application for different parts. October 1, 2016 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.
Short and Long Term Debt	WGL and Washington Gas satisfy their short-term financing requirements through the sale of commercial paper, financing arrangements with third-party lenders, or through bank borrowings. Due to the seasonal nature of the regulated utility and retail energy-marketing segments, 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 each WGL and Washington Gas is to maintain bank credit facilities in amounts equal to or greater than the expected maximum commercial paper position. WGL and Washington Gas issue long-term notes with individual terms regarding interest rates, maturities and call or put options. These notes can have maturity dates of one or more years from the date of issuance.
Income Tax Policy	Under ASC Topic 740, Income Taxes , Washington Gas recognizes any accrued interest associated with uncertain tax positions in interest expense and recognizes any accrued penalties associated with uncertain tax positions in other expenses in the statements of income.
Derivatives, Reporting Of Derivative Activity	Non-Utility Operations Asset Optimization. WGL Midstream enters into derivative contracts for the purpose of optimizing its storage and transportation capacity as well as managing the transportation and storage assets on behalf of third parties. WGL Midstream does not designate these derivatives as hedges under ASC Topic 815; therefore, changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations and may cause significant period-to-period volatility in earnings. Managing Price Risk. WGL Energy Services enters into certain derivative contracts as part of its strategy to manage the price risk associated with the sale and purchase of natural gas and electricity. WGL Energy Services designates a portion of these physical contracts related to the purchase of natural gas and electricity to serve our customers as "normal purchases and normal sales" and therefore, they are not subject to the fair value accounting requirements of ASC Topic 815. Derivative instruments not designated as "normal purchases and normal sales" are recorded at fair value on our consolidated balance sheets, and changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations, which may cause significant period-to-period volatility in earnings. WGL Energy Services does not designate derivatives as hedges under ASC Topic 815. Managing Interest-Rate Risk . WGL utilizes derivative instruments that are designed to limit the risk of interest-rate volatility associated with future debt issuances. 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 locking in 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 280. Regulatory sharing mechanisms provide for the annual realized profit from these transactions to be shared between Washington Gas' shareholders 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 locked-in operating margins that Washington Gas expects to ultimately realize from these transactions through the use of its storage and transportation capacity resources. 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. Managing Interest-Rate Risk . Washington Gas may utilize derivative instruments that are designed to minimize the risk of interest-rate volatility associated with planned issuances of debt securities. Any gains and losses associated with these types of derivatives are recorded as regulatory liabilities or assets, respectively, and amortized in accordance with regulatory requirements, typically over the life of the related debt. In May 2016, Washington Gas entered into a forward starting interest rate swap, with a notional amount of $ 125.0 million related to the expected issuance of 30-year debt in late 2016. The change in the fair value of the interest rate swap is reported as a regulatory asset. Non-Utility Operations Asset Optimization. WGL Midstream enters into derivative contracts for the purpose of optimizing its storage and transportation capacity as well as managing the transportation and storage assets on behalf of third parties. WGL Midstream does not designate these derivatives as hedges under ASC Topic 815; therefore, changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations and may cause significant period-to-period volatility in earnings. Managing Price Risk. WGL Energy Services enters into certain derivative contracts as part of its strategy to manage the price risk associated with the sale and purchase of natural gas and electricity. WGL Energy Services designates a portion of these physical contracts related to the purchase of natural gas and electricity to serve our customers as "normal purchases and normal sales" and therefore, they are not subject to the fair value accounting requirements of ASC Topic 815. Derivative instruments not designated as "normal purchases and normal sales" are recorded at fair value on our consolidated balance sheets, and changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations, which may cause significant period-to-period volatility in earnings. WGL Energy Services does not designate derivatives as hedges under ASC Topic 815. Managing Interest-Rate Risk . WGL utilizes derivative instruments that are designed to limit the risk of interest-rate volatility associated with future debt issuances. Collateral WGL 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 parental 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 WGL’s 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 sheet. Regulated Utility Operations 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.
Fair Value Measurement Policy	Our money market funds are Level 1 valuations and their carrying amount approximates fair value. Other short-term investments are primarily overnight investment accounts; their carrying amount approximates fair value based on Level 2 inputs. The maturity of our commercial paper outstanding at both June 30, 2016 and September 30, 2015 is under 30 days. Due to the short term nature of these notes, the carrying cost of our commercial paper approximates fair value using Level 2 inputs. Due to the short term nature of our project financing arrangements, the carrying cost approximates fair value using Level 2 inputs. Neither WGL’s nor Washington Gas’ long-term debt is actively traded. The fair value of long-term debt was estimated based on the quoted market prices of the U.S. Treasury issues having a similar term to maturity, adjusted for the credit quality of the debt issuer, WGL or Washington Gas. Our long-term debt fair value measurement is classified as Level 3. Recurring Basis We measure the fair value of our financial assets and liabilities using a combination of the income and market approach in accordance with ASC Topic 820. These financial assets and liabilities primarily consist of derivatives recorded on our balance sheet under ASC Topic 815 and short-term investments, 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 WGL. We value our derivative contracts based on an “in-exchange” premise, and 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.
Segment Reporting Policy	We have four reportable operating segments: regulated utility, retail energy-marketing, commercial energy systems and midstream energy services. The division of these segments into separate revenue generating components is based upon regulation, products and services. Our chief operating decision maker is our Chief Executive Officer and we evaluate segment performance based on Earnings Before Interest and Taxes (EBIT). EBIT is defined as earnings before interest and taxes from continuing operations. Items we do not include in EBIT are interest expense, intercompany financing activity, dividends on Washington Gas preferred stock, and income taxes. EBIT includes transactions between reportable segments. We also evaluate our operating segments based on other relevant factors, such as penetration into their respective markets and return on equity.
Investment Policy	The investment in MVP is accounted for under the HLBV equity method of accounting. The investment in Stonewall System is accounted for under the HLBV equity method of accounting. When determining how to account for our interests in other legal entities, WGL first evaluates if we are required to apply the variable interest entity (VIE) model of accounting to the entity. If the VIE model is not applicable, the entity is evaluated under the voting interest model. Under the VIE model, we have a controlling financial interest in a VIE (i.e. are the primary beneficiary) when we have current or potential rights that give us the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance combined with a variable interest that gives us the right to receive potentially significant benefits or the obligation to absorb potentially significant losses. When changes occur to the design of an entity, we reconsider whether it is subject to the VIE model. We continuously evaluate whether we have a controlling financial interest in a VIE. Under the voting interest model, we generally have a controlling financial interest in an entity where we currently hold, directly or indirectly, more than 50% of the voting rights or where we exercise control through substantive participating rights. However, we consider substantive rights held by other partners in determining if we hold a controlling financial interest, and in some cases, despite owning more than 50% of the common stock of an investee, an evaluation of our rights results in the determination that we do not have a controlling financial interest. We reevaluate whether we have a controlling financial interest in these entities when our voting or substantive participating rights change. Unconsolidated affiliates are unconsolidated VIEs and other entities evaluated under the voting interest method in which we do not have a controlling financial interest, but over which we have varying degrees of influence. Where we have significant influence, the affiliates are accounted for as equity method investments. Where we do not have significant influence, the affiliates are accounted for under the cost method. Investments in, and advances to, affiliated companies are presented in the caption “Investments in unconsolidated affiliates” in the accompanying Consolidated Balance Sheets. WGL uses the Hypothetical Liquidation at Book Value (HLBV) methodology for certain equity method investments when the capital structure of the equity investment results in different liquidation rights and priorities than what is reflected by the underlying percentage ownership interests as defined by an equity investment agreement. For investments accounted for under the HLBV method, simply applying the percentage ownership interest to GAAP net income in order to determine earnings or losses does not accurately represent the income allocation and cash flow distributions that will ultimately be received by the investors. The equity investment agreements for ASD Solar, LP (ASD), Meade Pipeline Co LLC (Meade), Mountain Valley Pipeline, LLC (Mountain Valley) and Stonewall Gas Gathering System (Stonewall System) have liquidation rights and priorities that are sufficiently different from the ownership percentages that the HLBV method was deemed appropriate. The calculation may vary in its complexity depending on the capital structure and the tax considerations for the investments. WGL applies HLBV using a balance sheet approach. When applying HLBV, WGL determines the amount that it would receive if an equity investment entity were to liquidate all of its assets at book value (as valued in accordance with GAAP) and distribute that cash to the investors based on the contractually defined liquidation priorities. The change in WGL's claim on the investee's book value at the beginning and end of the reporting period (adjusted for contributions and distributions) is WGL’s share of the earnings or losses from the equity investment for the period. Constitution is accounted for under the equity method of accounting; any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statements of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. Although WGL Midstream holds greater than a 50% interest in Meade, Meade is accounted for under the equity method of accounting because WGL Midstream does not have the power to direct the activities most significant to the economic performance of Meade. Meade is accounted for under the HLBV equity method of accounting, and any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statements of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. WGSW has master purchase agreements and master lease agreements with SunEdison, Inc. (SunEdison) and with Nextility, Inc. (Nextility) for sale/leaseback arrangements for residential and commercial solar systems. Our agreements with SunEdison and Nextility are accounted for as direct financing leases. WGSW records associated interests in the financing leases in “Other income (expenses)-net” line in the accompanying Consolidated Statements of Income. Our investment in ASD is accounted for under the HLBV equity method of accounting; any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statements of Income and are added to or subtracted from the carrying amount of WGSW’s investment balance.

Accounting Policies (Tables)

Accounting Policies (Tables)	9 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Lower of Cost or Market Pre-Tax Adjustments to Net Income	The following table shows the lower-of-cost or market adjustments recorded to net income for the three and nine months ended June 30, 2016 and 2015 . Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income Three Months Ended June 30, Nine Months Ended June 30, (In millions) 2016 2015 2016 2015 WGL (a) Operating revenues - non-utility $ 0.7 $ 0.9 $ (0.4 ) $ (19.6 ) Washington Gas Utility cost of gas — — $ — $ (1.0 ) Total Consolidated $ 0.7 $ 0.9 $ (0.4 ) $ (20.6 ) (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas.
Accounting Standards Adopted in Current Fiscal Year	ACCOUNTING STANDARDS ADOPTED IN FISCAL YEAR 2016 Standard Description Date of adoption Effect on the financial statements or other significant matters ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes The standard requires an entity to present deferred tax liabilities and assets as noncurrent in a classified statement of financial position. The current requirement that deferred tax liabilities and assets of a tax-paying component of an entity be offset by taxing jurisdiction and presented as a single amount remains the same. October 1, 2015 As a result of the standard, we have presented all deferred tax liabilities and assets, net, as non-current in "Deferred credits-Deferred income taxes" in the accompanying balance sheets, retrospectively for all periods presented. The adoption of this standard did not have a material effect on our financial statements. Refer to Note 7 — Income taxes , for further discussion of this standard.
Other Newly Issued Accounting Standards	OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required 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 For credit losses on financial instruments, 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. October 1, 2020 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting This standard simplifies several aspects of the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and statutory tax withholding requirements. October 1, 2017 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2014-09, Revenue from Contracts with Customers (Topic 606), including subsequent ASUs clarifying the guidance. ASU 2014-09 establishes a comprehensive revenue recognition model clarifying the method used to determine the timing and requirements for revenue recognition from contracts with customers. The disclosure requirements under the new standard will enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-02, Leases (Topic 842) This standard requires recognition of a right-to-use asset and lease liability on the statement of financial position and disclosure of key information about leasing arrangements. The standard requires application using a modified retrospective approach. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. We may elect early adoption. ASU 2016-01, Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The new standard significantly revises an entity’s accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2015-03 and ASU 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost and Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements The standard requires an entity to present debt issuance costs in the balance sheet as a direct deduction of the debt liability in a manner consistent with its accounting treatment of debt discounts. The standard requires retrospective application. An entity can defer and present debt issuance costs related to line-of-credit arrangements as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. October 1, 2016 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis The standard changes the analysis to be performed in determining whether certain types of legal entities should be consolidated, specifically the analysis of limited partnerships and similar entities, fee arrangements and related party relationships. The standard permits prospective or retrospective application for different parts. October 1, 2016 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.

Accounts Payable and Other Ac24

Accounts Payable and Other Accrued Liabilities (Tables)	9 Months Ended
	Jun. 30, 2016
Accounts Payable and Other Accrued Liabilities [Line Items]
Accounts Payable and Other Accrued Liabilities	The tables below provide details for the amounts included in “Accounts payable and other accrued liabilities” on the balance sheets for both WGL and Washington Gas. WGL Holdings, Inc. (In millions) June 30, 2016 September 30, 2015 Accounts payable—trade $ 290.1 $ 277.3 Employee benefits and payroll accruals 27.7 31.4 Other accrued liabilities 15.4 16.4 Total $ 333.2 $ 325.1
Washington Gas Light Company
Accounts Payable and Other Accrued Liabilities [Line Items]
Accounts Payable and Other Accrued Liabilities	Washington Gas Light Company (In millions) June 30, 2016 September 30, 2015 Accounts payable—trade $ 141.3 $ 122.2 Employee benefits and payroll accruals 25.8 29.5 Other accrued liabilities 8.4 7.6 Total $ 175.5 $ 159.3

Short-Term Debt (Tables)

Short-Term Debt (Tables)	9 Months Ended
	Jun. 30, 2016
Short-term Debt [Abstract]
Committed Credit Available	The following is a summary of committed credit available at June 30, 2016 and September 30, 2015 . Committed Credit Available ($ In millions) June 30, 2016 WGL (b) Washington Gas Total Consolidated Committed credit agreements Unsecured revolving credit facility, expires December 19, 2019 (a) $ 450.0 $ 350.0 $ 800.0 Less: Commercial Paper (156.0 ) (150.0 ) (306.0 ) Net committed credit available $ 294.0 $ 200.0 $ 494.0 Weighted average interest rate 0.68 % 0.48 % 0.58 % September 30, 2015 Committed credit agreements Unsecured revolving credit facility, expires December 19, 2019 (a) $ 450.0 $ 350.0 $ 800.0 Less: Commercial Paper (243.0 ) (89.0 ) (332.0 ) Net committed credit available $ 207.0 $ 261.0 $ 468.0 Weighted average interest rate 0.30 % 0.16 % 0.26 % (a) Both WGL and Washington Gas have the right to request extensions with the banks’ approval. WGL’s revolving credit facility permits it to borrow an additional $100 million , with the banks’ approval, for a total of $550 million . Washington Gas’ revolving credit facility permits it to borrow an additional $100 million , with the banks’ approval, for a total of $450 million . (b) WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Long-Term Debt (Table)

Long-Term Debt (Table)	9 Months Ended
	Jun. 30, 2016
Long-term Debt, by Current and Noncurrent [Abstract]
Long-Term Debt Outstanding	The following tables show the outstanding notes as of June 30, 2016 and September 30, 2015 . Long-Term Debt Outstanding ($ In millions) WGL (a) Washington Gas Total Consolidated June 30, 2016 Long-term debt (b) $ 500.0 $ 696.0 $ 1,196.0 Unamortized discount (1.6 ) (0.1 ) (1.7 ) Total Long-Term Debt $ 498.4 $ 695.9 $ 1,194.3 Weighted average interest rate 2.45 % 5.59 % 4.28 % September 30, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 Unamortized discount (1.7 ) (0.1 ) (1.8 ) Less—current maturities — (25.0 ) (25.0 ) Total Long-Term Debt $ 248.3 $ 695.9 $ 944.2 Weighted average interest rate 3.66 % 5.58 % 5.08 % (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. (b) Includes Senior Notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities.
Long-Term Debt Issuances	The following tables show long-term debt issuances and retirements for the nine months ended June 30, 2016 and 2015 . There were no retirements for WGL or Washington Gas for the nine months ended June 30, 2015 . Long-Term Debt Issuances and Retirements ($ In millions) Principal (b) Interest Rate Effective Cost (d) Nominal Maturity Date Nine Months Ended June 30, 2016 WGL (a) Issuances: 2/18/2016 $ 250.0 1.25 % (c) 1.25 % 2/18/2018 Total consolidated issuances $ 250.0 Washington Gas Retirements: 1/18/2016 $ 25.0 5.17 % n/a 1/18/2016 Total consolidated retirements $ 25.0 Nine Months Ended June 30, 2015 WGL (a) Issuances: 10/24/2014 $ 100.0 2.25 % 2.42 % 11/1/2019 10/24/2014 125.0 4.60 % 5.11 % 11/1/2044 12/16/2014 25.0 4.60 % 5.53 % 11/1/2044 Total $ 250.0 Washington Gas Issuances: 12/15/2014 $ 50.0 4.24 % 4.41 % 12/15/2044 Total $ 50.0 Total consolidated issuances $ 300.0 (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. (b) Represents face amount of senior notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. (c) Floating rate per annum that will be determined from time to time based on parameters set forth in the credit agreement. (d) The estimated effective cost of the issued notes.

Common Shareholders' Equity (Ta

Common Shareholders' Equity (Tables)	9 Months Ended
	Jun. 30, 2016
Schedule of Capitalization, Equity [Line Items]
Components of Common Shareholders' Equity	The tables below reflect the components of “Common shareholders’ equity” for WGL and “Common shareholder’s equity” for Washington Gas for the nine months ended June 30, 2016 . WGL Holdings, Inc. Components of Common Shareholders’ Equity (In thousands, except shares) Common Stock Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss, Net of Taxes Total Shares Amount Balance at September 30, 2015 49,728,662 $ 485,456 $ 14,934 $ 757,093 $ (14,236 ) $ 1,243,247 Net income — — — 177,474 — 177,474 Other comprehensive loss — — — — (19,844 ) (19,844 ) Stock-based compensation (a) 115,974 6,742 (3,652 ) (122 ) — 2,968 Issuance of common stock (b) 1,213,373 80,711 — — — 80,711 Dividends declared: Common stock — — — (72,485 ) — (72,485 ) Preferred stock — — — (990 ) — (990 ) Balance at June 30, 2016 51,058,009 $ 572,909 $ 11,282 $ 860,970 $ (34,080 ) $ 1,411,081 (a) Includes dividend equivalents related to our performance shares.
Washington Gas Light Company
Schedule of Capitalization, Equity [Line Items]
Components of Common Shareholders' Equity	Washington Gas Light Company Components of Common Shareholder’s Equity (In thousands, except shares) Common Stock Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss, Net of Taxes Total Shares Amount Balance at September 30, 2015 46,479,536 $ 46,479 $ 483,677 $ 557,848 $ (6,712 ) $ 1,081,292 Net income — — — 130,526 — 130,526 Other comprehensive income — — — — 370 370 Stock-based compensation — — 2,119 — — 2,119 Dividends declared: Common stock — — — (61,856 ) — (61,856 ) Preferred stock — — — (990 ) — (990 ) Other (a) 942 942 Balance at June 30, 2016 46,479,536 $ 46,479 $ 486,738 $ 625,528 $ (6,342 ) $ 1,152,403 (a) Represents a WGL contribution related to the transfer of a storage contract to an affiliate.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Earnings per Share	The following table reflects the computation of our basic and diluted EPS for the three and nine months ended June 30, 2016 and 2015 . Basic and Diluted EPS (In thousands, except per share data) Net Income (Loss) Applicable to Common Stock Shares Per Share Amount Three Months Ended June 30, 2016 Basic EPS $ 2,025 50,622 $ 0.04 Stock-based compensation plans — 283 Diluted EPS $ 2,025 50,905 $ 0.04 Three Months Ended June 30, 2015 Basic EPS $ (15,690 ) 49,729 $ (0.32 ) Stock-based compensation plans — — Diluted EPS $ (15,690 ) 49,729 $ (0.32 ) Nine Months Ended June 30, 2016 Basic EPS $ 176,484 50,158 $ 3.52 Stock-based compensation plans — 260 Diluted EPS $ 176,484 50,418 $ 3.50 Nine Months Ended June 30, 2015 Basic EPS $ 129,653 49,814 $ 2.60 Stock-based compensation plans — 242 Diluted EPS $ 129,653 50,056 $ 2.59

Derivative and Weather Relate29

Derivative and Weather Related Instruments (Tables)	9 Months Ended
	Jun. 30, 2016
Derivative [Line Items]
Absolute Notional Amounts of Open Positions on Derivative Instruments	At June 30, 2016 and September 30, 2015 , respectively, the absolute notional amounts of our derivatives were as follows: Absolute Notional Amounts of Open Positions on Derivative Instruments Derivative transactions WGL Holdings, Inc. Washington Gas June 30, 2016 Notional Amounts Natural Gas (In millions of therms) Asset Optimization 22,365.5 13,180.0 Retail sales 54.3 — Other risk-management activities 1,819.4 1,322.0 Electricity (In millions of kWhs) Retail sales 4,874.5 — Other risk-management activities (a) 25,300.1 — Interest Rate Swaps (In millions of dollars) $ 325.0 $ 125.0 September 30, 2015 Natural Gas (In millions of therms) Asset Optimization 20,829.2 13,316.7 Retail sales 52.2 — Other risk-management activities 1,811.7 1,381.8 Electricity (In millions of kWhs) Retail sales 4,292.7 — Other risk-management activities (a) 19,965.7 — Interest Rate Swaps (In millions of dollars) $ 125.0 $ — (a) Comprised primarily of electric swaps, financial transmission rights, physical forward purchases and slice of system, if any.
Balance Sheet Classification of Derivative Instruments	The following tables present the balance sheet classification for all derivative instruments as of June 30, 2016 and September 30, 2015 . WGL Holdings, Inc. Balance Sheet Classification of Derivative Instruments ($ In millions) Derivative Instruments Not Designated as Hedging Instruments Derivative Instruments Designated as Hedging Instruments As of June 30, 2016 Gross Derivative Assets Gross Derivative Liabilities Gross Derivative Assets Gross Derivative Liabilities Netting of Collateral Total (a) Current Assets—Derivatives $ 27.5 $ (11.0 ) $ — $ — $ — $ 16.5 Deferred Charges and Other Assets—Derivatives 43.2 (0.2 ) — — — 43.0 Current Liabilities—Derivatives 39.5 (139.3 ) — — 20.2 (79.6 ) Deferred Credits—Derivatives 21.0 (265.0 ) — (38.1 ) 8.0 (274.1 ) Total $ 131.2 $ (415.5 ) $ — $ (38.1 ) $ 28.2 $ (294.2 ) As of September 30, 2015 Current Assets—Derivatives $ 29.7 $ (6.8 ) $ — $ — $ — $ 22.9 Deferred Charges and Other Assets—Derivatives 32.3 (0.2 ) — — — 32.1 Current Liabilities—Derivatives 9.8 (76.2 ) — — 2.9 (63.5 ) Deferred Credits—Derivatives 2.7 (328.9 ) — (3.4 ) 7.3 (322.3 ) Total $ 74.5 $ (412.1 ) $ — $ (3.4 ) $ 10.2 $ (330.8 )
Gains and (Losses) on Derivative Instruments	The following table presents all gains and losses associated with derivative instruments for the three and nine months ended June 30, 2016 and 2015 . Gains and Losses on Derivative Instruments ($ In millions) WGL Holdings, Inc. Washington Gas Three Months Ended June 30, 2016 2015 2016 2015 Recorded to income Operating revenues—non-utility $ (39.0 ) $ (28.3 ) $ — $ — Utility cost of gas (24.9 ) (10.4 ) (24.9 ) (10.4 ) Non-utility cost of energy-related sales 48.4 3.2 — — Interest expense (0.1 ) — — — Recorded to regulatory assets Gas costs (29.4 ) (12.1 ) (29.4 ) (12.1 ) Other (8.8 ) — (8.8 ) — Recorded to other comprehensive income (a) (16.9 ) — — — Total $ (70.7 ) $ (47.6 ) $ (63.1 ) $ (22.5 ) Nine Months Ended June 30, 2016 2015 2016 2015 Recorded to income Operating revenues—non-utility $ 7.6 $ 46.0 $ — $ — Utility cost of gas 9.2 (20.4 ) 9.2 (20.4 ) Non-utility cost of energy-related sales 50.6 (35.9 ) — — Interest expense (0.2 ) (0.5 ) — — Recorded to regulatory assets Gas costs 24.9 (36.0 ) 24.9 (36.0 ) Other (8.8 ) — (8.8 ) — Recorded to other comprehensive income (a) (34.5 ) (8.0 ) — — Total $ 48.8 $ (54.8 ) $ 25.3 $ (56.4 ) (a) Represents the effective portion of our cash flow hedges.
Collateral Not Offset Against Derivative Assets and Liabilities	The table below presents collateral positions at June 30, 2016 and September 30, 2015 , respectively. Collateral Not Offset Against Derivative Assets and Liabilities (In millions) June 30, 2016 Collateral deposits posted with counterparties Cash collateral held representing an obligation Washington Gas $ 15.5 $ 0.1 WGL Energy Services 7.8 — WGL Midstream 8.1 2.4 September 30, 2015 Washington Gas $ 3.5 $ 3.8 WGL Energy Services 12.4 — WGL Midstream 3.5 0.4
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 June 30, 2016 and September 30, 2015 , respectively. Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features (In millions) WGL Holdings, Inc. Washington Gas June 30, 2016 Derivative liabilities with credit-risk-contingent features $ 46.3 $ 11.6 Maximum potential collateral requirements 30.7 11.0 September 30, 2015 Derivative liabilities with credit-risk-contingent features $ 61.7 $ 18.9 Maximum potential collateral requirements 54.6 18.8
Washington Gas Light Company
Derivative [Line Items]
Balance Sheet Classification of Derivative Instruments	Washington Gas Light Company Balance Sheet Classification of Derivative Instruments (b) ($ In millions) As of June 30, 2016 Gross Gross Netting of Total (a) Current Assets—Derivatives $ 4.2 $ (0.1 ) $ — $ 4.1 Deferred Charges and Other Assets—Derivatives 20.4 — — 20.4 Current Liabilities—Derivatives 7.8 (67.6 ) 0.1 (59.7 ) Deferred Credits—Derivatives 2.5 (228.7 ) 0.4 (225.8 ) Total $ 34.9 $ (296.4 ) $ 0.5 $ (261.0 ) As of September 30, 2015 Current Assets—Derivatives $ 5.2 $ (0.6 ) $ — $ 4.6 Deferred Charges and Other Assets—Derivatives 13.3 (0.1 ) — 13.2 Current Liabilities—Derivatives 1.9 (35.8 ) — (33.9 ) Deferred Credits—Derivatives — (269.7 ) — (269.7 ) Total $ 20.4 $ (306.2 ) $ — $ (285.8 ) (a) WGL 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 815. All recognized derivative contracts and associated financial collateral subject to a master netting arrangement or similar that is eligible for offset under ASC 815 have been presented net in the balance sheet. (b) Washington Gas did not have any derivative instruments outstanding that were designated as hedging instruments at June 30, 2016 or September 30, 2015 .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements Under the Fair Value Hierarchy	The following tables set forth financial instruments recorded at fair value as of June 30, 2016 and September 30, 2015 , respectively. 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. WGL Holdings, Inc. Fair Value Measurements Under the Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Total At June 30, 2016 Assets Natural gas related derivatives $ — $ 51.4 $ 58.3 $ 109.7 Electricity related derivatives — 2.0 19.5 21.5 Total Assets $ — $ 53.4 $ 77.8 $ 131.2 Liabilities Natural gas related derivatives $ — $ (76.3 ) $ (298.8 ) $ (375.1 ) Electricity related derivatives — (1.4 ) (30.2 ) (31.6 ) Interest rate derivatives — (46.9 ) — (46.9 ) Total Liabilities $ — $ (124.6 ) $ (329.0 ) $ (453.6 ) At September 30, 2015 Assets Natural gas related derivatives $ — $ 22.7 $ 28.5 $ 51.2 Electricity related derivatives — 2.0 21.3 23.3 Total Assets $ — $ 24.7 $ 49.8 $ 74.5 Liabilities Natural gas related derivatives $ — $ (33.9 ) $ (338.2 ) $ (372.1 ) Electricity related derivatives — (2.7 ) (37.3 ) (40.0 ) Interest rate derivatives — (3.4 ) — (3.4 ) Total Liabilities $ — $ (40.0 ) $ (375.5 ) $ (415.5 )
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, by contract type, as of June 30, 2016 and September 30, 2015 . Quantitative Information about Level 3 Fair Value Measurements Net Fair Value Valuation Techniques Unobservable Inputs Range ($ In millions) WGL Holdings, Inc. Natural gas related derivatives $(240.5) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.060) - $3.815 Option Model Natural Gas Basis Price (per dekatherm) ($1.060) - $3.815 Annualized Volatility of Spot Market Natural Gas 25.0% - 915.6% Electricity related derivatives $(10.7) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($6.20) - $69.70 Washington Gas Light Company Natural gas related derivatives $(243.3) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.019) - $3.750 Net Fair Value ($ In millions) WGL Holdings, Inc. Natural gas related derivatives $(309.7) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.441) - $3.580 Option Model Natural Gas Basis Price (per dekatherm) ($1.283) - $2.950 Annualized Volatility of Spot Market Natural Gas 22.5% - 867.0% Electricity related derivatives $(16.0) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($5.75) - $73.35 Washington Gas Light Company Natural gas related derivatives $(281.1) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.441) - $3.500
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs	The following tables are a summary of the changes in the fair value of our derivative instruments that are measured at net fair value on a recurring basis in accordance with ASC Topic 820 using significant Level 3 inputs during the three and nine months ended June 30, 2016 and 2015 , respectively. WGL Holdings, Inc. Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Total Three Months Ended June 30, 2016 Balance at April 1, 2016 $ (204.3 ) $ (30.5 ) $ (234.8 ) Realized and unrealized gains (losses) Recorded to income (8.9 ) 22.5 13.6 Recorded to regulatory assets—gas costs (27.6 ) — (27.6 ) Transfers into Level 3 0.1 — 0.1 Transfers out of Level 3 (0.2 ) — (0.2 ) Purchases — (10.7 ) (10.7 ) Settlements 0.4 8.0 8.4 Balance at June 30, 2016 $ (240.5 ) $ (10.7 ) $ (251.2 ) Three Months Ended June 30, 2015 Balance at April 1, 2015 $ (319.6 ) $ (10.5 ) $ (330.1 ) Realized and unrealized gains (losses) Recorded to income (33.6 ) (4.8 ) (38.4 ) Recorded to regulatory assets—gas costs (7.7 ) — (7.7 ) Transfers out of Level 3 3.9 — 3.9 Purchases — 3.9 3.9 Settlements 6.0 2.6 8.6 Balance at June 30, 2015 $ (351.0 ) $ (8.8 ) $ (359.8 ) Nine Months Ended June 30, 2016 Balance at October 1, 2015 $ (309.7 ) $ (16.0 ) $ (325.7 ) Realized and unrealized gains (losses) Recorded to income 34.6 (14.2 ) 20.4 Recorded to regulatory assets—gas costs 15.9 — 15.9 Transfers into Level 3 (0.8 ) — (0.8 ) Transfers out of Level 3 8.7 — 8.7 Purchases — (4.4 ) (4.4 ) Settlements 10.8 23.9 34.7 Balance at June 30, 2016 $ (240.5 ) $ (10.7 ) $ (251.2 ) Nine Months Ended June 30, 2015 Balance at October 1, 2014 $ (294.7 ) $ (5.0 ) $ (299.7 ) Realized and unrealized gains (losses) Recorded to income (51.0 ) (15.3 ) (66.3 ) Recorded to regulatory assets—gas costs (48.0 ) — (48.0 ) Transfers into Level 3 5.4 — 5.4 Transfers out of Level 3 3.6 — 3.6 Purchases — 7.3 7.3 Settlements 33.7 4.2 37.9 Balance at June 30, 2015 $ (351.0 ) $ (8.8 ) $ (359.8 )
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements	The table below sets forth the line items on the statements of income to which amounts are recorded for the three and nine months ended June 30, 2016 and 2015 , respectively, related to fair value measurements using significant Level 3 inputs. WGL Holdings, Inc. Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Total Three Months Ended June 30, 2016 Operating revenues—non-utility $ 6.5 $ (17.4 ) $ (10.9 ) Utility cost of gas (21.6 ) — (21.6 ) Non-utility cost of energy-related sales 6.2 39.9 46.1 Total $ (8.9 ) $ 22.5 $ 13.6 Three Months Ended June 30, 2015 Operating revenues—non-utility $ (22.3 ) $ (3.0 ) $ (25.3 ) Utility cost of gas (7.6 ) — (7.6 ) Non-utility cost of energy-related sales (3.7 ) (1.8 ) (5.5 ) Total $ (33.6 ) $ (4.8 ) $ (38.4 ) Nine Months Ended June 30, 2016 Operating revenues—non-utility $ 22.5 $ (25.9 ) $ (3.4 ) Utility cost of gas 3.3 — 3.3 Non-utility cost of energy-related sales 8.8 11.7 20.5 Total $ 34.6 $ (14.2 ) $ 20.4 Nine Months Ended June 30, 2015 Operating revenues—non-utility $ (20.7 ) $ 21.0 $ 0.3 Utility cost of gas (30.3 ) — (30.3 ) Non-utility cost of energy-related sales — (36.3 ) (36.3 ) Total $ (51.0 ) $ (15.3 ) $ (66.3 )
Unrealized Gains (Losses) Recorded for Level 3 Measurements	Unrealized gains (losses) attributable to derivative assets and liabilities measured using significant Level 3 inputs were recorded as follows, for the three and nine months ended June 30, 2016 and 2015 , respectively. WGL Holdings, Inc. Unrealized Gains (Losses) Recorded for Level 3 Measurements (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Total Three Months Ended June 30, 2016 Recorded to income Operating revenues—non-utility $ 6.7 $ (10.3 ) $ (3.6 ) Utility cost of gas (22.2 ) — (22.2 ) Non-utility cost of energy-related sales 5.2 33.2 38.4 Recorded to regulatory assets—gas costs (28.9 ) — (28.9 ) Total $ (39.2 ) $ 22.9 $ (16.3 ) Three Months Ended June 30, 2015 Recorded to income Operating revenues—non-utility $ (21.3 ) $ 0.8 $ (20.5 ) Utility cost of gas (1.8 ) — (1.8 ) Non-utility cost of energy-related sales (5.6 ) 2.5 (3.1 ) Recorded to regulatory assets—gas costs (9.2 ) — (9.2 ) Total $ (37.9 ) $ 3.3 $ (34.6 ) Nine Months Ended June 30, 2016 Recorded to income Operating revenues—non-utility $ 26.1 $ (6.7 ) $ 19.4 Utility cost of gas (0.2 ) — (0.2 ) Non-utility cost of energy-related sales 2.6 15.1 17.7 Recorded to regulatory assets—gas costs 9.2 — 9.2 Total $ 37.7 $ 8.4 $ 46.1 Nine Months Ended June 30, 2015 Recorded to income Operating revenues—non-utility $ (17.6 ) $ 21.7 $ 4.1 Utility cost of gas (23.1 ) — (23.1 ) Non-utility cost of energy-related sales (1.7 ) (31.5 ) (33.2 ) Recorded to regulatory assets—gas costs (38.1 ) — (38.1 ) Total $ (80.5 ) $ (9.8 ) $ (90.3 )
Fair Value of Financial Instruments	The following table presents the carrying amounts and estimated fair values of our financial instruments at June 30, 2016 and September 30, 2015 . WGL Holdings, Inc. Fair Value of Financial Instruments June 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 20.5 $ 20.5 $ 11.0 $ 11.0 Other short-term investments (a) $ 0.1 $ 0.1 $ 0.4 $ 0.4 Commercial paper (b) $ 306.0 $ 306.0 $ 332.0 $ 332.0 Project financing (b) $ 52.3 $ 52.3 $ — $ — Long-term debt (c) $ 1,194.3 $ 1,373.1 $ 944.2 $ 1,057.9
Washington Gas Light Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements Under the Fair Value Hierarchy	Washington Gas Light Company Fair Value Measurements Under the Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Total At June 30, 2016 Assets Natural gas related derivatives $ — $ 15.7 $ 19.2 $ 34.9 Total Assets $ — $ 15.7 $ 19.2 $ 34.9 Liabilities Natural gas related derivatives $ — $ (25.1 ) $ (262.5 ) $ (287.6 ) Interest rate derivatives — (8.8 ) — (8.8 ) Total Liabilities $ — $ (33.9 ) $ (262.5 ) $ (296.4 ) At September 30, 2015 Assets Natural gas related derivatives $ — $ 6.9 $ 13.5 $ 20.4 Total Assets $ — $ 6.9 $ 13.5 $ 20.4 Liabilities Natural gas related derivatives $ — $ (11.6 ) $ (294.6 ) $ (306.2 ) Total Liabilities $ — $ (11.6 ) $ (294.6 ) $ (306.2 )
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs	Washington Gas Light Company Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs (In millions) Natural Gas Related Derivatives Three Months Ended June 30, 2016 Balance at April 1, 2016 $ (194.3 ) Realized and unrealized gains (losses) Recorded to income (21.6 ) Recorded to regulatory assets—gas costs (27.6 ) Settlements 0.2 Balance at June 30, 2016 $ (243.3 ) Three Months Ended June 30, 2015 Balance at April 1, 2015 $ (299.8 ) Realized and unrealized gains (losses) Recorded to income (7.6 ) Recorded to regulatory assets—gas costs (7.7 ) Transfers out of Level 3 2.8 Settlements 5.1 Balance at June 30, 2015 $ (307.2 ) Nine Months Ended June 30, 2016 Balance at October 1, 2015 $ (281.1 ) Realized and unrealized gains (losses) Recorded to income 3.3 Recorded to regulatory assets—gas costs 15.9 Transfers into Level 3 (0.2 ) Transfers out of Level 3 8.8 Settlements 10.0 Balance at June 30, 2016 $ (243.3 ) Nine Months Ended June 30, 2015 Balance at October 1, 2014 $ (270.6 ) Realized and unrealized gains (losses) Recorded to income (30.3 ) Recorded to regulatory assets—gas costs (48.0 ) Transfers into Level 3 5.4 Transfers out of Level 3 2.5 Settlements 33.8 Balance at June 30, 2015 $ (307.2 )
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements	Washington Gas Light Company Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements (In millions) Natural Gas Related Derivatives Three Months Ended June 30, 2016 Utility cost of gas $ (21.6 ) Total $ (21.6 ) Three Months Ended June 30, 2015 Utility cost of gas $ (7.6 ) Total $ (7.6 ) Nine Months Ended June 30, 2016 Utility cost of gas $ 3.3 Total $ 3.3 Nine Months Ended June 30, 2015 Utility cost of gas $ (30.3 ) Total $ (30.3 )
Unrealized Gains (Losses) Recorded for Level 3 Measurements	Washington Gas Light Company Unrealized Gains (Losses) Recorded for Level 3 Measurements (In millions) Natural Gas Related Derivatives Three Months Ended June 30, 2016 Recorded to income - utility cost of gas $ (22.2 ) Recorded to regulatory assets—gas costs (28.9 ) Total $ (51.1 ) Three Months Ended June 30, 2015 Recorded to income - utility cost of gas $ (1.8 ) Recorded to regulatory assets—gas costs (9.2 ) Total $ (11.0 ) Nine Months Ended June 30, 2016 Recorded to income - utility cost of gas $ (0.2 ) Recorded to regulatory assets—gas costs 9.2 Total $ 9.0 Nine Months Ended June 30, 2015 Recorded to income - utility cost of gas $ (23.1 ) Recorded to regulatory assets—gas costs (38.1 ) Total $ (61.2 )
Fair Value of Financial Instruments	Washington Gas Light Company Fair Value of Financial Instruments June 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 4.0 $ 4.0 $ 4.3 $ 4.3 Other short-term investments (a) $ 0.1 $ 0.1 $ 0.4 $ 0.4 Commercial paper (b) $ 150.0 $ 150.0 $ 89.0 $ 89.0 Project financing (b) $ 52.3 $ 52.3 $ — $ — Long-term debt (c) $ 695.9 $ 868.2 $ 695.9 $ 811.9 (a) Balance is located in cash and cash equivalents in the accompanying balance sheets. These amounts may be offset by outstanding checks. (b) Balance is located in notes payable in the accompanying balance sheets. (c) Includes adjustments for current maturities and unamortized discounts, as applicable.

Operating Segment Reporting (Ta

Operating Segment Reporting (Tables)	9 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Operating Segment Financial Information	The following tables present operating segment information for the three and nine months ended June 30, 2016 and 2015 . Operating Segment Financial Information (In thousands) Operating Revenues (a) Depreciation and Amortization Equity in EBIT Total Assets Capital Expenditures Equity Method Investments Three Months Ended June 30, 2016 Regulated utility $ 187,077 $ 29,632 $ — $ (20,458 ) $ 4,467,449 $ 106,773 $ — Retail energy-marketing 266,214 233 — 49,544 484,511 768 — Commercial energy systems 20,842 3,900 2,162 8,286 787,248 34,125 65,289 Midstream energy services (17,989 ) 26 2,365 (16,908 ) 433,395 — 217,491 Other activities — — — (517 ) 201,354 — — Eliminations (b) (15,557 ) (5 ) — 178 (631,144 ) — — Total consolidated $ 440,587 $ 33,786 $ 4,527 $ 20,125 $ 5,742,813 $ 141,666 $ 282,780 Three Months Ended June 30, 2015 Regulated utility $ 190,345 $ 27,740 $ — $ (6,262 ) $ 4,095,646 $ 75,413 $ — Retail energy-marketing 268,249 151 — 16,654 458,745 — — Commercial energy systems 14,674 2,787 544 3,750 611,380 27,271 64,323 Midstream energy services (25,801 ) 31 718 (26,607 ) 196,770 85 56,967 Other activities — — — (970 ) 106,861 — — Eliminations (b) (6,294 ) (13 ) — (541 ) (492,362 ) — — Total consolidated $ 441,173 $ 30,696 $ 1,262 $ (13,976 ) $ 4,977,040 $ 102,769 $ 121,290 Nine Months Ended June 30, 2016 Regulated utility $ 934,347 $ 86,318 $ — $ 243,102 $ 4,467,449 $ 267,230 $ — Retail energy-marketing 925,180 872 — 52,055 484,511 7,595 — Commercial energy systems 57,066 11,105 5,554 10,251 787,248 73,769 65,289 Midstream energy services 16,223 97 5,004 17,631 433,395 — 217,491 Other activities — — — (2,773 ) 201,354 — — Eliminations (b) (43,156 ) (24 ) — (416 ) (631,144 ) — — Total consolidated $ 1,889,660 $ 98,368 $ 10,558 $ 319,850 $ 5,742,813 $ 348,594 $ 282,780 Nine Months Ended June 30, 2015 Regulated utility $ 1,193,232 $ 81,958 $ — $ 238,645 $ 4,095,646 $ 235,707 $ — Retail energy-marketing 1,003,339 470 — 39,185 458,745 5 — Commercial energy systems 35,745 7,693 1,623 4,731 611,380 81,246 64,323 Midstream energy services (17,997 ) 93 1,865 (23,343 ) 196,770 85 56,967 Other activities — — 750 (8,915 ) 106,861 — — Eliminations (b) (22,176 ) (55 ) — (592 ) (492,362 ) — — Total consolidated $ 2,192,143 $ 90,159 $ 4,238 $ 249,711 $ 4,977,040 $ 317,043 $ 121,290 (a) Operating revenues are reported gross of revenue taxes. Operating revenue amounts in the “Eliminations” row represent total intersegment revenues associated with sales from the regulated utility segment to the retail energy-marketing segment. Midstream Energy Services’ cost of energy related sales is netted with its gross revenues. (b) Eliminations include any trading activities, including mark-to market valuations, between WGL Midstream and WGL Energy Services, project financing intercompany loans and a timing difference between Commercial Energy Systems’ recognition of revenue for the sale of Renewable Energy Credits (RECs) to Retail Energy-Marketing and Retail Energy-Marketing’s recognition of the associated expense. Retail Energy-Marketing has recorded a portion of the REC’s purchased as inventory to be used in future periods at which time they will be expensed.
Reconciliation from EBIT to net income applicable to common stock	The following table provides a reconciliation from EBIT to net income applicable to common stock. Three Months Ended June 30, Nine Months Ended June 30, (In thousands) 2016 2015 2016 2015 Total consolidated EBIT $ 20,125 $ (13,976 ) $ 319,850 $ 249,711 Interest expense 12,998 13,140 38,757 38,704 Income (loss) before income taxes 7,127 (27,116 ) 281,093 211,007 Income tax expense (benefit) 4,772 (11,756 ) 103,619 80,364 Net income (loss) 2,355 (15,360 ) 177,474 130,643 Dividends on Washington Gas Light Company preferred stock 330 330 990 990 Net income (loss) applicable to common stock $ 2,025 $ (15,690 ) $ 176,484 $ 129,653

Other Investment (Tables)

Other Investment (Tables)	9 Months Ended
	Jun. 30, 2016
Other Investments [Abstract]
Minimum Payments Receivable for Direct Financing Leases	Minimum future lease payments receivable under direct financing leases over the next five fiscal years and thereafter are as follows: Minimum Payments Receivable for Direct Financing Leases (In millions) Remainder of 2016 $ 0.7 2017 2.2 2018 2.2 2019 2.1 2020 2.2 Thereafter 30.7 Total $ 40.1
Location of Investments	The balance sheet location of the investments discussed in this footnote at June 30, 2016 and September 30, 2015 are as follows: WGL Holdings, Inc. Balance Sheet Location of Other Investments As of June 30, 2016 (In millions) VIEs Non-VIEs Total Assets Investments in unconsolidated affiliates $ 133.4 $ 149.4 $ 282.8 Investments in direct financing leases, capital leases 31.3 — 31.3 Accounts receivable 1.2 6.8 (a) 8.0 Total assets $ 165.9 $ 156.2 $ 322.1 As of September 30, 2015 (In millions) Assets Investments in unconsolidated affiliates $ 94.0 $ 42.9 $ 136.9 Investments in direct financing leases, capital leases 35.2 — 35.2 Accounts receivable 2.0 4.2 (a) 6.2 Total assets $ 131.2 $ 47.1 $ 178.3 (a) Represents the financing provided to another partner in Mountain Valley to fund its capital commitment. Acquired ownership interest represents the collateral for repayment of the financing. The income statement location of the investments discussed in this footnote for the three and nine months ended June 30, 2016 and 2015 are as follows: WGL Holdings, Inc. Income Statement Location of Other Investments Three Months Ended June 30, 2016 Nine Months Ended June 30, 2016 (In millions) VIEs Non-VIEs Total VIEs Non-VIEs Total Equity in earnings of unconsolidated affiliates $ 2.2 $ 2.4 $ 4.6 $ 5.5 $ 5.1 $ 10.6 Depreciation and amortization — — — 0.2 — 0.2 Operations and maintenance — — — 3.0 — 3.0 Other income (expense) —net 0.8 — 0.8 2.4 (0.1 ) 2.3 Net income $ 3.0 $ 2.4 $ 5.4 $ 4.7 $ 5.0 $ 9.7 Three Months Ended June 30, 2015 Nine Months Ended June 30, 2015 Equity in earnings of unconsolidated affiliates $ 0.8 $ 0.5 $ 1.3 $ 2.4 $ 1.8 $ 4.2 Depreciation and amortization 0.1 — 0.1 0.2 — 0.2 Other income (expenses)—net 1.0 — 1.0 2.4 (5.6 ) (3.2 ) Net income (loss) $ 1.7 $ 0.5 $ 2.2 $ 4.6 $ (3.8 ) $ 0.8

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Jun. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	The following table presents the receivables and payables from associated companies as of June 30, 2016 and September 30, 2015 . Washington Gas Receivables / Payables from Associated Companies (In millions) June 30, 2016 September 30, 2015 Receivables from Associated Companies $ 11.5 $ 3.2 Payables to Associated Companies $ 73.1 $ 68.6 The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Washington Gas - Gas Balancing Service Charges Three Months Ended June 30, Nine Months Ended June 30, (In millions) 2016 2015 2016 2015 Gas balancing service charge $ 5.5 $ 5.3 $ 21.7 $ 19.8

Pension and Other Post-Retire34

Pension and Other Post-Retirement Benefit Plan (Tables)	9 Months Ended
	Jun. 30, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Components of Net Periodic Benefit Costs (Income)	The following table shows the components of net periodic benefit costs (income) recognized in our financial statements during the three and nine months ended June 30, 2016 and 2015 . Components of Net Periodic Benefit Costs (Income) Three Months Ended June 30, 2016 2015 (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 3.6 $ 1.2 $ 3.9 $ 1.8 Interest cost 10.3 3.2 9.7 3.7 Expected return on plan assets (10.2 ) (5.1 ) (11.2 ) (5.2 ) Amortization of prior service cost (credit) — (4.4 ) 0.1 (3.8 ) Amortization of net actuarial loss 4.3 0.3 4.7 1.1 Net periodic benefit cost (income) 8.0 (4.8 ) 7.2 (2.4 ) Amount allocated to construction projects (1.5 ) 1.1 (1.2 ) 0.5 Amount deferred as regulatory asset/liability — net 1.8 (0.1 ) 1.8 (0.1 ) Amount charged (credited) to expense $ 8.3 $ (3.8 ) $ 7.8 $ (2.0 ) Nine Months Ended June 30, 2016 2015 Service cost $ 10.7 $ 3.4 $ 11.6 $ 5.3 Interest cost 31.0 9.8 29.3 11.0 Expected return on plan assets (30.7 ) (15.3 ) (33.5 ) (15.6 ) Amortization of prior service cost (credit) 0.2 (13.2 ) 0.2 (11.4 ) Amortization of net actuarial loss 12.7 0.9 14.1 3.3 Net periodic benefit cost (income) 23.9 (14.4 ) 21.7 (7.4 ) Amount allocated to construction projects (4.1 ) 3.0 (3.4 ) 1.5 Amount deferred as regulatory asset/liability — net 5.3 (0.2 ) 5.3 (0.2 ) Amount charged (credited) to expense $ 25.1 $ (11.6 ) $ 23.6 $ (6.1 )

Accumulated Other Comprehensi35

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Changes in Accumulated Other Comprehensive Income (Loss) by Component	The following tables show the changes in accumulated other comprehensive income (loss) for WGL and Washington Gas by component for the three and nine months ended June 30, 2016 and 2015 . WGL Holdings, Inc. Changes in Accumulated Other Comprehensive Loss by Component (In thousands) Three Months Ended June 30, Nine Months Ended June 30, 2016 2015 2016 2015 Beginning Balance $ (24,258 ) $ (11,643 ) $ (14,236 ) $ (7,961 ) Qualified cash flow hedging instruments (a) (16,995 ) 49 (34,545 ) (7,994 ) Amortization of net prior service credit (b) (216 ) (170 ) (644 ) (511 ) Amortization of net actuarial loss (b) 420 529 1,258 1,503 Current-period other comprehensive income (loss) (16,791 ) 408 (33,931 ) (7,002 ) Income tax expense (benefit) related to other comprehensive income (loss) (6,969 ) 163 (14,087 ) (3,565 ) Ending Balance $ (34,080 ) $ (11,398 ) $ (34,080 ) $ (11,398 ) (a) Cash flow hedging instruments represent interest rate swap agreements related to future debt issuances. Refer to Note 8- Derivative and Weather-related Instruments for further discussion of the interest rate swap agreements. (b) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14- Pension and other post-retirement benefit plans for additional details. Washington Gas Light Company Changes in Accumulated Other Comprehensive Loss by Component (In thousands) Three Months Ended June 30, Nine Months Ended June 30, 2016 2015 2016 2015 Beginning Balance $ (6,464 ) $ (6,031 ) $ (6,712 ) $ (6,413 ) Amortization of net prior service credit (a) (216 ) (170 ) (644 ) (511 ) Amortization of net actuarial loss (a) 420 529 1,258 1,503 Current-period other comprehensive income 204 359 614 992 Income tax expense related to other comprehensive income 82 143 244 394 Ending Balance $ (6,342 ) $ (5,815 ) $ (6,342 ) $ (5,815 ) (a) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14-Pension and other post-retirement benefit plans for additional details.

- Accounting Policies Accountin

- Accounting Policies Accounting Policies (Narrative) (Details) $ in Thousands	Jun. 01, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)subsidiary	Sep. 30, 2015USD ($)
Accounting Policies [Table] [Line Items]
Investments in direct financing leases, capital leases			$ 31,262	$ 35,234
Accounts receivable			310,094	276,358
Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Accounts receivable			$ 155,288	$ 126,356
Washington Gas Light Company | Springfield Operations Center
Accounting Policies [Table] [Line Items]
Proceeds from Sale of Building	$ 20,300
Selling and Administrative Expense	$ 500
Washington Gas Resources
Accounting Policies [Table] [Line Items]
Number of subsidiaries | subsidiary			4
WGL
Accounting Policies [Table] [Line Items]
Lease impairment reserve			$ 3,000
Nextility | Washington Gas Resources
Accounting Policies [Table] [Line Items]
Lease impairment reserve			3,000
Investments in direct financing leases, capital leases			$ 2,200
ASDHI | Washington Gas Resources
Accounting Policies [Table] [Line Items]
Impairment loss		$ 5,600

Accounting Policies (Details)

Accounting Policies (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Inventory [Line Items]
Lower of cost or market adjustment		$ 0.7	$ 0.9	$ (0.4)	$ (20.6)
WGL | Operating revenues - non-utility
Inventory [Line Items]
Lower of cost or market adjustment	[1]	0.7	0.9	(0.4)	(19.6)
Washington Gas Light Company | Utility cost of gas
Inventory [Line Items]
Lower of cost or market adjustment		$ 0	$ 0	$ 0	$ (1)
[1]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Accounts Payable and Other Ac38

Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Accounts Payable and Other Accrued Liabilities [Line Items]
Accounts payable—trade	$ 290,100	$ 277,300
Employee benefits and payroll accruals	27,700	31,400
Other accrued liabilities	15,400	16,400
Total	333,160	325,146
Washington Gas Light Company
Accounts Payable and Other Accrued Liabilities [Line Items]
Accounts payable—trade	141,300	122,200
Employee benefits and payroll accruals	25,800	29,500
Other accrued liabilities	8,400	7,600
Total	$ 175,500	$ 159,280

Short-Term Debt (Details)

Short-Term Debt (Details) - USD ($)		Jun. 30, 2016	Sep. 30, 2015
Short-term Debt [Line Items]
Less: Commercial Paper		$ (358,342,000)	$ (332,000,000)
Committed Credit
Short-term Debt [Line Items]
Unsecured revolving credit facility, expires December 19, 2019	[1]	800,000,000	800,000,000
Less: Commercial Paper		(306,000,000)	(332,000,000)
Net committed credit available		$ 494,000,000	$ 468,000,000
Weighted average interest rate		0.58%	0.26%
WGL
Short-term Debt [Line Items]
Outstanding bank loans		$ 0	$ 0
WGL | Committed Credit
Short-term Debt [Line Items]
Unsecured revolving credit facility, expires December 19, 2019	[1],[2]	450,000,000	450,000,000
Less: Commercial Paper	[2]	(156,000,000)	(243,000,000)
Net committed credit available	[2]	$ 294,000,000	$ 207,000,000
Weighted average interest rate	[2]	0.68%	0.30%
Revolving credit facility maximum borrowing capacity		$ 550,000,000
Revolving credit facility additional borrowings		100,000,000
Washington Gas Light Company
Short-term Debt [Line Items]
Less: Commercial Paper		(202,342,000)	$ (89,000,000)
Outstanding bank loans		0	0
Project financing receivable		56,600,000
Project financing payable		52,300,000
Reserve for bad debt		0
Washington Gas Light Company | Committed Credit
Short-term Debt [Line Items]
Unsecured revolving credit facility, expires December 19, 2019	[1]	350,000,000	350,000,000
Less: Commercial Paper		(150,000,000)	(89,000,000)
Net committed credit available		$ 200,000,000	$ 261,000,000
Weighted average interest rate		0.48%	0.16%
Revolving credit facility maximum borrowing capacity		$ 450,000,000
Revolving credit facility additional borrowings		$ 100,000,000
[1]	Both WGL and Washington Gas have the right to request extensions with the banks’ approval. WGL’s revolving credit facility permits it to borrow an additional $100 million, with the banks’ approval, for a total of $550 million. Washington Gas’ revolving credit facility permits it to borrow an additional $100 million, with the banks’ approval, for a total of $450 million.
[2]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Long-Term Debt (Details)

Long-Term Debt (Details) - USD ($)		Feb. 18, 2016	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015
Debt Instrument [Line Items]
Less-current maturities			$ 0		$ (25,000,000)
Total Consolidated Outstanding
Debt Instrument [Line Items]
Principal	[1]		1,196,000,000		971,000,000
Unamortized Discount			(1,700,000)		(1,800,000)
Less-current maturities					(25,000,000)
Total			$ 1,194,300,000		$ 944,200,000
Interest rate			4.28%		5.08%
WGL
Debt Instrument [Line Items]
Principal	[1],[2]		$ 500,000,000		$ 250,000,000
Unamortized Discount	[2]		(1,600,000)		(1,700,000)
Less-current maturities	[2]				0
Total	[2]		$ 498,400,000		$ 248,300,000
Interest rate	[2]		2.45%		3.66%
WGL | Term Loans
Debt Instrument [Line Items]
Unused Borrowing Capacity, Amount		$ 100,000,000
Term of extension option		1 year
Term Loans Maximum Borrowing Capacity		$ 350,000,000
Principal		$ 250,000,000
Nominal Maturity Date		Feb. 18, 2018
WGL | Issuances
Debt Instrument [Line Items]
Total	[3],[4]			$ 250,000,000
WGL | Issuances | 2/18/2018
Debt Instrument [Line Items]
Principal	[3],[4]		$ 250,000,000
Interest rate	[5]		1.25%
Effective cost	[4],[6]		1.25%
Nominal Maturity Date	[4]		Feb. 18, 2018
WGL | Issuances | 11/1/2019
Debt Instrument [Line Items]
Principal	[3],[4]			$ 100,000,000
Interest rate	[4]			2.25%
Effective cost	[4],[6]			2.42%
Nominal Maturity Date	[4]			Nov. 1, 2019
WGL | Issuances | 11/1/2044
Debt Instrument [Line Items]
Principal	[3],[4]			$ 125,000,000
Interest rate	[4]			4.60%
Effective cost	[4],[6]			5.11%
Nominal Maturity Date	[4]			Nov. 1, 2044
WGL | Issuances | 11/01/2044
Debt Instrument [Line Items]
Principal	[3],[4]			$ 25,000,000
Interest rate	[4]			4.60%
Effective cost	[4],[6]			5.53%
Nominal Maturity Date	[4]			Nov. 1, 2044
WGL | Retirements
Debt Instrument [Line Items]
Total				$ 0
WGL | Retirements | 1/18/2016
Debt Instrument [Line Items]
Principal	[3]		$ 25,000,000
Interest rate			5.17%
Nominal Maturity Date			Jan. 18, 2016
WGL | Total Consolidated Issuances
Debt Instrument [Line Items]
Total	[3],[4]		$ 250,000,000
WGL | Total Consolidated Retirements
Debt Instrument [Line Items]
Total	[3]		25,000,000
Washington Gas Light Company
Debt Instrument [Line Items]
Principal	[1]		696,000,000		$ 721,000,000
Unamortized Discount			(100,000)		(100,000)
Less-current maturities			0		(25,000,000)
Total			$ 695,900,000		$ 695,900,000
Interest rate			5.59%		5.58%
Washington Gas Light Company | Medium-term Notes
Debt Instrument [Line Items]
Unused Borrowing Capacity, Amount			$ 600,000,000		$ 600,000,000
Washington Gas Light Company | Issuances
Debt Instrument [Line Items]
Total	[3]			50,000,000
Washington Gas Light Company | Issuances | 12/15/2044
Debt Instrument [Line Items]
Principal	[3]			$ 50,000,000
Interest rate				4.24%
Effective cost	[6]			4.41%
Nominal Maturity Date				Dec. 15, 2044
Washington Gas Light Company | Retirements
Debt Instrument [Line Items]
Total				$ 0
Total Consolidated Company | Total Consolidated Issuances
Debt Instrument [Line Items]
Total	[3]			$ 300,000,000
[1]	Includes Senior Notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities.
[2]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.
[3]	Represents face amount of senior notes and term loans for WGL and both MTNs and private placement notes for Washington Gas.
[4]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.
[5]	Floating rate per annum that will be determined from time to time based on parameters set forth in the credit agreement.
[6]	The estimated effective cost of the issued notes.

Common Shareholders' Equity (De

Common Shareholders' Equity (Details) - USD ($) $ in Thousands		Nov. 24, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Balance at September 30, 2015 (in shares)					49,728,662
Common shareholders' equity, beginning balance					$ 1,243,247
Net income			$ 2,355	$ (15,360)	177,474	$ 130,643
Other comprehensive income (loss)			$ (9,822)	$ 245	(19,844)	$ (3,437)
Stock-based compensation	[1]				$ 2,968
Stock-based compensation plans (in shares)			283,000	0	260,000	242,000
Issuance of common stock	[2]				$ 80,711
Issuance of Common Stock (in shares)	[2]				1,213,373
Common shareholders' equity, ending balance			$ 1,411,081		$ 1,411,081
Balance at June 30, 2016 (in shares)			51,058,009		51,058,009
Dividends declared:
Common stock					$ (72,485)
Preferred stock					(990)
Common Stock
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					485,456
Stock-based compensation	[1]				$ 6,742
Stock-based compensation plans (in shares)	[1]				115,974
Issuance of common stock	[2]				$ 80,711
Common shareholders' equity, ending balance			$ 572,909		572,909
Paid-In Capital
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					14,934
Stock-based compensation	[1]				(3,652)
Common shareholders' equity, ending balance			11,282		11,282
Retained Earnings
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					757,093
Net income					177,474
Stock-based compensation	[1]				(122)
Common shareholders' equity, ending balance			860,970		860,970
Dividends declared:
Common stock					(72,485)
Preferred stock					(990)
Accumulated Other Comprehensive Income (Loss), Net of Taxes
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					(14,236)
Other comprehensive income (loss)					(19,844)
Common shareholders' equity, ending balance			(34,080)		(34,080)
At-the-market
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Issuance of common stock	[2]				$ 78,200
Issuance of Common Stock (in shares)					1,162,305
Total Aggregate Sales Price of Stock to be Issued		$ 150,000
Washington Gas Light Company
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Balance at September 30, 2015 (in shares)					46,479,536
Common shareholders' equity, beginning balance					$ 1,081,292
Net income			(18,519)	$ (11,424)	130,526	$ 128,221
Other comprehensive income (loss)			122	$ 216	370	$ 598
Stock-based compensation					2,119
Common shareholders' equity, ending balance			$ 1,152,403		$ 1,152,403
Balance at June 30, 2016 (in shares)			46,479,536		46,479,536
Dividends declared:
Common stock					$ (61,856)
Preferred stock					(990)
Other	[3]				942
Washington Gas Light Company | Common Stock
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					46,479
Common shareholders' equity, ending balance			$ 46,479		46,479
Washington Gas Light Company | Paid-In Capital
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					483,677
Stock-based compensation					2,119
Common shareholders' equity, ending balance			486,738		486,738
Dividends declared:
Other	[3]				942
Washington Gas Light Company | Retained Earnings
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					557,848
Net income					130,526
Common shareholders' equity, ending balance			625,528		625,528
Dividends declared:
Common stock					(61,856)
Preferred stock					(990)
Washington Gas Light Company | Accumulated Other Comprehensive Income (Loss), Net of Taxes
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance					(6,712)
Other comprehensive income (loss)					370
Common shareholders' equity, ending balance			$ (6,342)		$ (6,342)
[1]	Includes dividend equivalents related to our performance shares.
[2]	Includes shares issued under the ATM program (discussed below) and the dividend reinvestment and common stock purchase plans.
[3]	Represents a WGL contribution related to the transfer of a storage contract to an affiliate.

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net Income (Loss) applicable to common stock	$ 2,025	$ (15,690)	$ 176,484	$ 129,653
Basic EPS (in shares)	50,622,000	49,729,000	50,158,000	49,814,000
Stock-based compensation plans (in shares)	283,000	0	260,000	242,000
Diluted EPS (in shares)	50,905,000	49,729,000	50,418,000	50,056,000
Basic EPS (in dollars per share)	$ 0.04	$ (0.32)	$ 3.52	$ 2.60
Diluted EPS (in dollars per share)	$ 0.04	$ (0.32)	$ 3.50	$ 2.59
Antidilutive securities excluded from computation of earnings per share	0	317,000	0	0

Income Taxes-Balance Sheet (Det

Income Taxes-Balance Sheet (Details) - USD ($)	Jun. 30, 2016	Sep. 30, 2015
Income Tax Expense Benefit Details [Line Items]
Unrecognized tax benefits	$ 38,600,000	$ 38,600,000
Washington Gas Light Company
Income Tax Expense Benefit Details [Line Items]
Accrued interest related to uncertain tax positions	$ 0	0
Adjustments for New Accounting Principle, Early Adoption [Member] | WGL
Income Tax Expense Benefit Details [Line Items]
Current Deferred Tax Asset Reclassed to NonCurrent Deferred Tax Liability		32,800,000
Adjustments for New Accounting Principle, Early Adoption [Member] | Washington Gas Light Company
Income Tax Expense Benefit Details [Line Items]
Current Deferred Tax Asset Reclassed to NonCurrent Deferred Tax Liability		$ 24,700,000

Derivative and Weather Relate44

Derivative and Weather Related Instruments (Narrative) (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2016USD ($)derivativeCounterparties	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)derivativeCounterparties	Jun. 30, 2015USD ($)	Sep. 30, 2015USD ($)derivative
Washington Gas Light Company
Asset Optimization [Abstract]
Gain (loss) on asset optimization transactions, net pretax	$ (19,000,000)	$ (2,900,000)	$ 30,300,000	$ 14,200,000
Unrealized gain (loss) on asset optimization derivative instruments, net pretax	(25,200,000)	(10,400,000)	8,000,000	(13,300,000)
Derivative, Collateral [Abstract]
Collateral already posted, aggregate fair value	$ 0		$ 0		$ 0
Concentration of Credit Risk
Number of counterparties | Counterparties	2		2
Percentage of credit exposure	10.00%		10.00%
Obligation to counterparties	$ 30,300,000		$ 30,300,000
Washington Gas Light Company | Interest Rate Swap
Asset Optimization [Abstract]
Derivative notional amount	125,000,000		125,000,000		0
Washington Gas Light Company | Interest Rate Swap | Regulated Utility
Asset Optimization [Abstract]
Derivative notional amount	125,000,000		125,000,000
WGL Energy Services
Derivative, Collateral [Abstract]
Collateral already posted, aggregate fair value	$ 2,800,000		$ 2,800,000		10,300,000
Concentration of Credit Risk
Number of counterparties | Counterparties	4		4
Percentage of credit exposure	10.00%		10.00%
Obligation to counterparties	$ 4,400,000		$ 4,400,000
Gain (losses) on weather related instruments, pretax	(500,000)	$ (500,000)	3,800,000	$ 2,700,000
WGL Midstream
Derivative, Collateral [Abstract]
Collateral already posted, aggregate fair value	$ 0		$ 0		0
Concentration of Credit Risk
Number of counterparties | Counterparties	2		2
Percentage of credit exposure	10.00%		10.00%
Obligation to counterparties	$ 27,000,000		$ 27,000,000
WGL
Derivative, Collateral [Abstract]
Collateral already posted, aggregate fair value	4,800,000		4,800,000		0
WGL | Interest Rate Swap
Asset Optimization [Abstract]
Derivative notional amount	$ 325,000,000		325,000,000		$ 125,000,000
WGL | Interest Rate Swap | Non Utility
Asset Optimization [Abstract]
Derivative Ineffectiveness			$ 0
Number of interest rate derivatives held | derivative	2		2		2
Derivative notional amount	$ 75,000,000		$ 75,000,000		$ 125,000,000

Derivative and Weather Relate45

Derivative and Weather Related Instruments (Details) kWh in Millions, MMBTU in Millions, $ in Millions		Jun. 30, 2016USD ($)kWhMMBTU	Sep. 30, 2015USD ($)kWhMMBTU
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		$ 28.2	$ 10.2
Total	[1]	(294.2)	(330.8)
Derivative Instruments Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Liabilities		(38.1)	(3.4)
Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		131.2	74.5
Gross Derivative Liabilities		(415.5)	(412.1)
Current Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Total	[1]	16.5	22.9
Current Assets-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		27.5	29.7
Gross Derivative Liabilities		(11)	(6.8)
Deferred Charges and Other Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Total	[1]	43	32.1
Deferred Charges and Other Assets-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		43.2	32.3
Gross Derivative Liabilities		(0.2)	(0.2)
Current Liabilities-Derivatives
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		20.2	2.9
Total	[1]	(79.6)	(63.5)
Current Liabilities-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		39.5	9.8
Gross Derivative Liabilities		(139.3)	(76.2)
Deferred Credits-Derivatives
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		8	7.3
Total	[1]	(274.1)	(322.3)
Deferred Credits-Derivatives | Derivative Instruments Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Liabilities		(38.1)	(3.4)
Deferred Credits-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		21	2.7
Gross Derivative Liabilities		$ (265)	$ (328.9)
Asset Optimization
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		2,236,550,000	2,082,920,000
Retail sales
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		5,430,000	5,220,000
Other risk-management activities
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		181,940,000	181,170,000
Washington Gas Light Company
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	$ 34.9	$ 20.4
Gross Derivative Liabilities	[2]	(296.4)	(306.2)
Netting of Collateral	[2]	0.5	0
Total	[1],[2]	(261)	(285.8)
Derivative, Collateral [Abstract]
Derivative, Collateral, Right to Reclaim Cash		15.5	3.5
Obligation to return cash		0.1	3.8
Washington Gas Light Company | Current Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	4.2	5.2
Gross Derivative Liabilities	[2]	(0.1)	(0.6)
Total	[1],[2]	4.1	4.6
Washington Gas Light Company | Deferred Charges and Other Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	20.4	13.3
Gross Derivative Liabilities	[2]	0	(0.1)
Total	[1],[2]	20.4	13.2
Washington Gas Light Company | Current Liabilities-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	7.8	1.9
Gross Derivative Liabilities	[2]	(67.6)	(35.8)
Netting of Collateral	[2]	0.1	0
Total	[1],[2]	(59.7)	(33.9)
Washington Gas Light Company | Deferred Credits-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	2.5	0
Gross Derivative Liabilities	[2]	(228.7)	(269.7)
Netting of Collateral	[2]	0.4	0
Total	[1],[2]	$ (225.8)	$ (269.7)
Washington Gas Light Company | Asset Optimization
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		1,318,000,000	1,331,670,000
Washington Gas Light Company | Other risk-management activities
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		132,200,000	138,180,000
Washington Gas Light Company | Interest Rate Swap
Absolute Notional Amounts of Open Positions on Derivative Instruments
Derivative notional amount		$ 125	$ 0
WGL Energy Services
Derivative, Collateral [Abstract]
Derivative, Collateral, Right to Reclaim Cash		7.8	12.4
WGL Midstream
Derivative, Collateral [Abstract]
Derivative, Collateral, Right to Reclaim Cash		8.1	3.5
Obligation to return cash		$ 2.4	$ 0.4
WGL | Retail sales
Absolute Notional Amounts of Open Positions on Derivative Instruments
Electricity notional amounts (in kWhs) | kWh		4,874.5	4,292.7
WGL | Other risk-management activities
Absolute Notional Amounts of Open Positions on Derivative Instruments
Electricity notional amounts (in kWhs) | kWh	[3]	25,300.1	19,965.7
WGL | Interest Rate Swap
Absolute Notional Amounts of Open Positions on Derivative Instruments
Derivative notional amount		$ 325	$ 125
[1]	WGL 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 815. All recognized derivative contracts and associated financial collateral subject to a master netting arrangement or similar that is eligible for offset under ASC 815 have been presented net in the balance sheet.
[2]	Washington Gas did not have any derivative instruments outstanding that were designated as hedging instruments at June 30, 2016 or September 30, 2015.
[3]	Comprised primarily of electric swaps, financial transmission rights, physical forward purchases and slice of system, if any.

Derivative and Weather Relate46

Derivative and Weather Related Instruments (Gains and Losses) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Gains and (Losses) on Derivative Instruments
Recorded to other comprehensive income	[1]	$ (16,995)	$ 49	$ (34,545)	$ (7,994)
Total Gains (losses) on derivative instruments		(70,700)	(47,600)	48,800	(54,800)
Operating revenues—non-utility
Gains and (Losses) on Derivative Instruments
Recorded to income		(39,000)	(28,300)	7,600	46,000
Utility cost of gas
Gains and (Losses) on Derivative Instruments
Recorded to income		(24,900)	(10,400)	9,200	(20,400)
Non-utility cost of energy-related sales
Gains and (Losses) on Derivative Instruments
Recorded to income		48,400	3,200	50,600	(35,900)
Interest expense
Gains and (Losses) on Derivative Instruments
Recorded to income		(100)	0	(200)	(500)
Gas costs
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		(29,400)	(12,100)	24,900	(36,000)
Other
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		(8,800)	0	(8,800)	0
Recorded to other comprehensive income
Gains and (Losses) on Derivative Instruments
Recorded to other comprehensive income	[2]	(16,900)	0	(34,500)	(8,000)
Washington Gas Light Company
Gains and (Losses) on Derivative Instruments
Total Gains (losses) on derivative instruments		(63,100)	(22,500)	25,300	(56,400)
Washington Gas Light Company | Utility cost of gas
Gains and (Losses) on Derivative Instruments
Recorded to income		(24,900)	(10,400)	9,200	(20,400)
Washington Gas Light Company | Gas costs
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		(29,400)	(12,100)	24,900	(36,000)
Washington Gas Light Company | Other
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		$ (8,800)	$ 0	$ (8,800)	$ 0
[1]	Cash flow hedging instruments represent interest rate swap agreements related to future debt issuances. Refer to Note 8- Derivative and Weather-related Instruments for further discussion of the interest rate swap agreements.
[2]	Represents the effective portion of our cash flow hedges.

Derivative and Weather Relate47

Derivative and Weather Related Instruments (Aggregate Fair Value) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Sep. 30, 2015
Potential Collateral Requirements for Derivative Liabilities with Credit-risk-Contingent Features
Derivative liabilities with credit-risk-contingent features	$ 46.3	$ 61.7
Maximum potential collateral requirements	30.7	54.6
Washington Gas Light Company
Potential Collateral Requirements for Derivative Liabilities with Credit-risk-Contingent Features
Derivative liabilities with credit-risk-contingent features	11.6	18.9
Maximum potential collateral requirements	$ 11	$ 18.8

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Hierarchy) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	$ 131.2	$ 74.5
Liabilities	(453.6)	(415.5)
Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	109.7	51.2
Liabilities	(375.1)	(372.1)
Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	21.5	23.3
Liabilities	(31.6)	(40)
Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	(46.9)	(3.4)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0	0
Liabilities	0	0
Level 1 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0	0
Liabilities	0	0
Level 1 | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0	0
Liabilities	0	0
Level 1 | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	53.4	24.7
Liabilities	(124.6)	(40)
Level 2 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	51.4	22.7
Liabilities	(76.3)	(33.9)
Level 2 | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	2	2
Liabilities	(1.4)	(2.7)
Level 2 | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	(46.9)	(3.4)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	77.8	49.8
Liabilities	(329)	(375.5)
Level 3 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	58.3	28.5
Liabilities	(298.8)	(338.2)
Level 3 | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	19.5	21.3
Liabilities	(30.2)	(37.3)
Level 3 | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	0	0
Washington Gas Light Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	34.9	20.4
Liabilities	(296.4)	(306.2)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	34.9	20.4
Liabilities	(287.6)	(306.2)
Washington Gas Light Company | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	(8.8)
Washington Gas Light Company | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0	0
Liabilities	0	0
Washington Gas Light Company | Level 1 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0	0
Liabilities	0	0
Washington Gas Light Company | Level 1 | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	0
Washington Gas Light Company | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	15.7	6.9
Liabilities	(33.9)	(11.6)
Washington Gas Light Company | Level 2 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	15.7	6.9
Liabilities	(25.1)	(11.6)
Washington Gas Light Company | Level 2 | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	(8.8)
Washington Gas Light Company | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	19.2	13.5
Liabilities	(262.5)	(294.6)
Washington Gas Light Company | Level 3 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	19.2	13.5
Liabilities	(262.5)	$ (294.6)
Washington Gas Light Company | Level 3 | Interest Rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	$ 0

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative information) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2016USD ($)$ / MwH$ / dekatherm	Sep. 30, 2015USD ($)$ / MwH$ / dekatherm	Mar. 31, 2016USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Sep. 30, 2014USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (251.2)	$ (325.7)	$ (234.8)	$ (359.8)	$ (330.1)	$ (299.7)
Natural Gas Related Derivatives
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (240.5)	$ (309.7)	(204.3)	(351)	(319.6)	(294.7)
Natural Gas Related Derivatives | Discounted Cash Flow | Maximum | Natural Gas Basis Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour)	3.815	3.580
Natural Gas Related Derivatives | Discounted Cash Flow | Minimum | Natural Gas Basis Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour)	(1.060)	(1.441)
Natural Gas Related Derivatives | Option Model | Maximum | Natural Gas Basis Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour)	3.815	2.950
Natural Gas Related Derivatives | Option Model | Maximum | Annualized Volatility Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Option Volatility Percentage	915.60%	867.00%
Natural Gas Related Derivatives | Option Model | Minimum | Natural Gas Basis Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour)	(1.060)	(1.283)
Natural Gas Related Derivatives | Option Model | Minimum | Annualized Volatility Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Option Volatility Percentage	25.00%	22.50%
Electricity Related Derivatives
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (10.7)	$ (16)	(30.5)	(8.8)	(10.5)	(5)
Electricity Related Derivatives | Discounted Cash Flow | Maximum | Electricity Congestion Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour) | $ / MwH	69.70	73.35
Electricity Related Derivatives | Discounted Cash Flow | Minimum | Electricity Congestion Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour) | $ / MwH	(6.20)	(5.75)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (243.3)	$ (281.1)	$ (194.3)	$ (307.2)	$ (299.8)	$ (270.6)
Washington Gas Light Company | Natural Gas Related Derivatives | Discounted Cash Flow | Maximum | Natural Gas Basis Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour)	3.750	3.500
Washington Gas Light Company | Natural Gas Related Derivatives | Discounted Cash Flow | Minimum | Natural Gas Basis Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Input price (usd per dekatherm/megawatt hour)	(1.019)	(1.441)

Fair Value Measurements (Reconc

Fair Value Measurements (Reconciliation with Level 3 Inputs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ (234.8)	$ (330.1)	$ (325.7)	$ (299.7)
Recorded to income	13.6	(38.4)	20.4	(66.3)
Recorded to regulatory assets—gas costs	(27.6)	(7.7)	15.9	(48)
Transfers into Level 3	0.1		(0.8)	5.4
Transfers out of Level 3	(0.2)	3.9	8.7	3.6
Purchases	(10.7)	3.9	(4.4)	7.3
Settlements	8.4	8.6	34.7	37.9
Ending balance	(251.2)	(359.8)	(251.2)	(359.8)
Natural Gas Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(204.3)	(319.6)	(309.7)	(294.7)
Recorded to income	(8.9)	(33.6)	34.6	(51)
Recorded to regulatory assets—gas costs	(27.6)	(7.7)	15.9	(48)
Transfers into Level 3	0.1		(0.8)	5.4
Transfers out of Level 3	(0.2)	3.9	8.7	3.6
Settlements	0.4	6	10.8	33.7
Ending balance	(240.5)	(351)	(240.5)	(351)
Electricity Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(30.5)	(10.5)	(16)	(5)
Recorded to income	22.5	(4.8)	(14.2)	(15.3)
Purchases	(10.7)	3.9	(4.4)	7.3
Settlements	8	2.6	23.9	4.2
Ending balance	(10.7)	(8.8)	(10.7)	(8.8)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(194.3)	(299.8)	(281.1)	(270.6)
Recorded to income	(21.6)	(7.6)	3.3	(30.3)
Recorded to regulatory assets—gas costs	(27.6)	(7.7)	15.9	(48)
Transfers into Level 3	0		(0.2)	5.4
Transfers out of Level 3	0	2.8	8.8	2.5
Settlements	0.2	5.1	10	33.8
Ending balance	$ (243.3)	$ (307.2)	$ (243.3)	$ (307.2)

Fair Value Measurements (Realiz

Fair Value Measurements (Realized and Unrealized Gains and Losses with Level 3 Measurements) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	$ 13.6	$ (38.4)	$ 20.4	$ (66.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	(28.9)	(9.2)	9.2	(38.1)
Total	(16.3)	(34.6)	46.1	(90.3)
Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(8.9)	(33.6)	34.6	(51)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	(28.9)	(9.2)	9.2	(38.1)
Total	(39.2)	(37.9)	37.7	(80.5)
Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	22.5	(4.8)	(14.2)	(15.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Total	22.9	3.3	8.4	(9.8)
Operating revenues—non-utility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(10.9)	(25.3)	(3.4)	0.3
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(3.6)	(20.5)	19.4	4.1
Operating revenues—non-utility | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	6.5	(22.3)	22.5	(20.7)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	6.7	(21.3)	26.1	(17.6)
Operating revenues—non-utility | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(17.4)	(3)	(25.9)	21
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(10.3)	0.8	(6.7)	21.7
Utility cost of gas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(21.6)	(7.6)	3.3	(30.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(22.2)	(1.8)	(0.2)	(23.1)
Utility cost of gas | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(21.6)	(7.6)	3.3	(30.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(22.2)	(1.8)	(0.2)	(23.1)
Non-utility cost of energy-related sales
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	46.1	(5.5)	20.5	(36.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	38.4	(3.1)	17.7	(33.2)
Non-utility cost of energy-related sales | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	6.2	(3.7)	8.8	0
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	5.2	(5.6)	2.6	(1.7)
Non-utility cost of energy-related sales | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	39.9	(1.8)	11.7	(36.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	33.2	2.5	15.1	(31.5)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(21.6)	(7.6)	3.3	(30.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	(28.9)	(9.2)	9.2	(38.1)
Total	(51.1)	(11)	9	(61.2)
Washington Gas Light Company | Utility cost of gas | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and unrealized gains (losses) recorded to income for Level 3 measurements	(21.6)	(7.6)	3.3	(30.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	$ (22.2)	$ (1.8)	$ (0.2)	$ (23.1)

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Amounts and Estimated Fair Value) (Details) - USD ($) $ in Millions		Jun. 30, 2016	Sep. 30, 2015
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	$ 20.5	$ 11
Other Short-term Investments	[1]	0.1	0.4
Commercial Paper	[2]	306	332
Project financing	[2]	52.3
Long-term debt	[3]	1,194.3	944.2
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	20.5	11
Other Short-term Investments	[1]	0.1	0.4
Commercial Paper	[2]	306	332
Project financing	[2]	52.3
Long-term debt	[3]	1,373.1	1,057.9
Washington Gas Light Company | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	4	4.3
Other Short-term Investments	[1]	0.1	0.4
Commercial Paper	[2]	150	89
Project financing	[2]	52.3
Long-term debt	[3]	695.9	695.9
Washington Gas Light Company | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	4	4.3
Other Short-term Investments	[1]	0.1	0.4
Commercial Paper	[2]	150	89
Project financing	[2]	52.3
Long-term debt	[3]	$ 868.2	$ 811.9
[1]	Balance is located in cash and cash equivalents in the accompanying balance sheets. These amounts may be offset by outstanding checks.
[2]	Balance is located in notes payable in the accompanying balance sheets.
[3]	Includes adjustments for current maturities and unamortized discounts, as applicable.

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in direct financing leases, capital leases		$ 31,262	$ 35,234
Washington Gas Resources | Nextility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lease Impairment		3,000
Investments in direct financing leases, capital leases		$ 2,200
Washington Gas Resources | ASDHI
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment loss	$ 5,600

Operating Segment (Narrative) (

Operating Segment (Narrative) (Details)	9 Months Ended
	Jun. 30, 2016segment
Segment Reporting [Abstract]
Number of operating segments	4

Operating Segment Financial Inf

Operating Segment Financial Information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015
Operating Segment Financial Information [Line Items]
Operating Revenue, Regulated Utility		$ 181,622	$ 185,179	$ 912,612	$ 1,173,396
Operating Revenue, Non-Utility		258,965	255,994	977,048	1,018,747
Operating Revenues	[1]	440,587	441,173	1,889,660	2,192,143
Depreciation and Amortization		33,786	30,696	98,368	90,159
Equity in earnings of unconsolidated affiliates		4,527	1,262	10,558	4,238
EBIT		20,125	(13,976)	319,850	249,711
Total Assets		5,742,813	4,977,040	5,742,813	4,977,040	$ 5,261,359
Capital Expenditures		141,666	102,769	348,594	317,043
Equity Method Investments		282,780	121,290	282,780	121,290
Other activities
Operating Segment Financial Information [Line Items]
Equity in earnings of unconsolidated affiliates					750
EBIT		(517)	(970)	(2,773)	(8,915)
Total Assets		201,354	106,861	201,354	106,861
Eliminations
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1],[2]	(15,557)	(6,294)	(43,156)	(22,176)
Depreciation and Amortization	[2]	(5)	(13)	(24)	(55)
EBIT	[2]	178	(541)	(416)	(592)
Total Assets	[2]	(631,144)	(492,362)	(631,144)	(492,362)
Regulated utility | Operating Segments
Operating Segment Financial Information [Line Items]
Operating Revenue, Regulated Utility	[1]	187,077	190,345	934,347	1,193,232
Depreciation and Amortization		29,632	27,740	86,318	81,958
EBIT		(20,458)	(6,262)	243,102	238,645
Total Assets		4,467,449	4,095,646	4,467,449	4,095,646
Capital Expenditures		106,773	75,413	267,230	235,707
Retail energy-marketing | Operating Segments
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1]	266,214	268,249	925,180	1,003,339
Depreciation and Amortization		233	151	872	470
EBIT		49,544	16,654	52,055	39,185
Total Assets		484,511	458,745	484,511	458,745
Capital Expenditures		768	0	7,595	5
Commercial energy systems | Operating Segments
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1]	20,842	14,674	57,066	35,745
Depreciation and Amortization		3,900	2,787	11,105	7,693
Equity in earnings of unconsolidated affiliates		2,162	544	5,554	1,623
EBIT		8,286	3,750	10,251	4,731
Total Assets		787,248	611,380	787,248	611,380
Capital Expenditures		34,125	27,271	73,769	81,246
Equity Method Investments		65,289	64,323	65,289	64,323
Midstream energy services | Operating Segments
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1]	(17,989)	(25,801)	16,223	(17,997)
Depreciation and Amortization		26	31	97	93
Equity in earnings of unconsolidated affiliates		2,365	718	5,004	1,865
EBIT		(16,908)	(26,607)	17,631	(23,343)
Total Assets		433,395	196,770	433,395	196,770
Capital Expenditures			85		85
Equity Method Investments		$ 217,491	$ 56,967	$ 217,491	$ 56,967
[1]	Operating revenues are reported gross of revenue taxes. Operating revenue amounts in the “Eliminations” row represent total intersegment revenues associated with sales from the regulated utility segment to the retail energy-marketing segment. Midstream Energy Services’ cost of energy related sales is netted with its gross revenues.
[2]	Eliminations include any trading activities, including mark-to market valuations, between WGL Midstream and WGL Energy Services, project financing intercompany loans and a timing difference between Commercial Energy Systems’ recognition of revenue for the sale of Renewable Energy Credits (RECs) to Retail Energy-Marketing and Retail Energy-Marketing’s recognition of the associated expense. Retail Energy-Marketing has recorded a portion of the REC’s purchased as inventory to be used in future periods at which time they will be expensed.

Operating Segment - Reconcilati

Operating Segment - Reconcilation from EBIT to Net Income Applicable to Common Stock (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting [Abstract]
Total consolidated EBIT	$ 20,125	$ (13,976)	$ 319,850	$ 249,711
Interest expense	12,998	13,140	38,757	38,704
INCOME (LOSS) BEFORE INCOME TAXES	7,127	(27,116)	281,093	211,007
Income tax expense (benefit)	4,772	(11,756)	103,619	80,364
Net income (loss)	2,355	(15,360)	177,474	130,643
Dividends on Washington Gas Light Company preferred stock	330	330	990	990
Net Income (Loss) applicable to common stock	$ 2,025	$ (15,690)	$ 176,484	$ 129,653

Other Investments (Narrative) (

Other Investments (Narrative) (Details) $ in Thousands, MMBTU in Millions	9 Months Ended		12 Months Ended
	Jun. 30, 2016USD ($)MMBTUBcfecompanyinvestmentagreementmi	Jun. 30, 2015USD ($)	Sep. 30, 2015USD ($)	Feb. 29, 2016	Mar. 31, 2015	Sep. 30, 2014USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Number of investments qualifying as variable interest entities | investment	4
Investments in unconsolidated affiliates	$ 282,780		$ 136,884
Investments in direct financing leases, capital leases	$ 31,262		35,234
WGL Midstream | Meade
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Pipeline length in miles | mi	185
Transportation and delivery capacity in dekatherms per day | MMBTU	1.7
Estimated Investment in Meade	$ 410,000
Ownership percentage	55.00%
Investments in unconsolidated affiliates	$ 68,100		30,500
Maximum financial exposure	$ 68,400
WGL Midstream | Constitution
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Ownership percentage	10.00%
Investments in unconsolidated affiliates	$ 39,900
Estimated investment In Constitution	$ 95,500
WGL Midstream | Mountain Valley Pipeline
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Transportation and delivery capacity in dekatherms per day | MMBTU	2
Ownership percentage					7.00%
Investments in unconsolidated affiliates	$ 16,700
WGL Midstream | Mountain Valley Pipeline | External Partners
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Minimum financial exposure	$ 97,900
Ownership interest in joint venture after funding requirements are met	3.00%
Pro rata share of project cost	$ 6,800
WGL Midstream | Mountain Valley Pipeline | Scenario, Plan
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Pro rata share of project cost	228,000
WGL Midstream | Mountain Valley Pipeline | Performance guarantee | External Partners
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Minimum financial exposure	6,000
WGL Midstream | Mountain Valley Pipeline | Performance guarantee | WGL Midstream
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Minimum financial exposure	$ 14,000
WGL Midstream | Stonewall
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Ownership percentage				35.00%
Expected decrease in equity method investment ownership percentage	30.00%
Investments in unconsolidated affiliates	$ 92,800
Difference between carrying amount and underlying equity	9,100
Investment in Stonewall System	$ 89,400
Pipeline gathering capacity | Bcfe	1.4
WGSW | SunEdison/Nextility
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Investments in direct financing leases, capital leases	$ 32,500		37,200
Current investment recorded in accounts receivable	1,200		2,000
Unamortized investment tax credits	14,000		14,700
Residual value	9,700
Tax related items	4,400
Unearned income	18,700
Initial direct costs	700
Impairment loss	$ 3,000
Number of agreements | agreement	2
Number of counterparties | company	2
WGSW | Nextility
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Investments in direct financing leases, capital leases	$ 2,200
Impairment loss	3,000
WGSW | ASD
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Investments in unconsolidated affiliates	65,300		$ 63,500
Maximum financial exposure	72,600
Difference between carrying amount and underlying equity	$ 35,800
Washington Gas Resources Corp. | ASDHI
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost method investments						$ 5,600
Impairment loss		$ 5,600

Other Investments Financing Lea

Other Investments Financing Leases Table (Details) - WGSW $ in Millions	Jun. 30, 2016USD ($)
Minimum Payments Receivable for Direct Financing Leases
Remainder of 2016	$ 0.7
2,017	2.2
2,018	2.2
2,019	2.1
2,020	2.2
Thereafter	30.7
Total	$ 40.1

Other Investments Balance Sheet

Other Investments Balance Sheet Location Table (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Sep. 30, 2015
Assets [Abstract]
Investments in unconsolidated affiliates		$ 282,780	$ 136,884
Investments in direct financing leases, capital leases		31,262	35,234
Allowance for doubtful accounts		(24,798)	(26,224)
VIEs
Assets [Abstract]
Investments in unconsolidated affiliates		133,400	94,000
Investments in direct financing leases, capital leases		31,300	35,200
Accounts receivable		1,200	2,000
Total assets		165,900	131,200
Non VIEs
Assets [Abstract]
Investments in unconsolidated affiliates		149,400	42,900
Accounts receivable	[1]	6,800	4,200
Total assets		156,200	47,100
Total
Assets [Abstract]
Investments in unconsolidated affiliates		282,800	136,900
Investments in direct financing leases, capital leases		31,300	35,200
Accounts receivable		8,000	6,200
Total assets		$ 322,100	$ 178,300
[1]	Represents the financing provided to another partner in Mountain Valley to fund its capital commitment. Acquired ownership interest represents the collateral for repayment of the financing.

Other Investments Income Statem

Other Investments Income Statement Location Table (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	$ 4,527	$ 1,262	$ 10,558	$ 4,238
Operation and maintenance	97,461	98,642	296,813	295,309
Other income (expenses)-net	1,915	2,329	3,689	(1,688)
Net income (loss)	2,355	(15,360)	177,474	130,643
VIEs
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	2,200	800	5,500	2,400
Depreciation and amortization	0	100	200	200
Operation and maintenance	0		3,000
Other income (expenses)-net	800	1,000	2,400	2,400
Net income (loss)	3,000	1,700	4,700	4,600
Non VIEs
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	2,400	500	5,100	1,800
Depreciation and amortization	0	0	0	0
Operation and maintenance	0		0
Other income (expenses)-net	0	0	(100)	(5,600)
Net income (loss)	2,400	500	5,000	(3,800)
Total Other Investments
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	4,600	1,300	10,600	4,200
Depreciation and amortization	0	100	200	200
Operation and maintenance	0		3,000
Other income (expenses)-net	800	1,000	2,300	(3,200)
Net income (loss)	$ 5,400	$ 2,200	$ 9,700	$ 800

Related Party Transactions (Det

Related Party Transactions (Details) $ in Thousands	Apr. 01, 2016MMBTU$ / dekatherm	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Sep. 30, 2015USD ($)
Washington Gas Light Company
Related Party Transaction [Line Items]
Receivables from associated companies		$ 11,500		$ 11,500		$ 3,200
Payables to associated companies		73,100		73,100		68,600
WGL Energy Services | Washington Gas Light Company
Related Party Transaction [Line Items]
Accounts payable, related parties		4,900		4,900		500
Washington Gas Light Company
Related Party Transaction [Line Items]
Receivables from associated companies		11,488		11,488		3,176
Payables to associated companies		73,106		73,106		68,623
Gas Volume in dekatherms | MMBTU	723,706
Price of gas | $ / dekatherm	0.594
Cash received				900
Washington Gas Light Company | WGL Energy Services
Related Party Transaction [Line Items]
Gas balancing service charge		5,500	$ 5,300	21,700	$ 19,800
Receivables purchased from related party		$ 12,700		$ 12,700		$ 6,600

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Sep. 30, 2015	Aug. 05, 2014
Washington Gas Light Company
Commitments And Contingencies [Line Items]
Excess payment amount			$ 2.4
Estimated reimbursement to competitive service providers		$ 2.4
Parent Company | Washington Gas Light Company | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	$ 30.6
Parent Company | WGL Energy Services | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	238.1
Parent Company | WGL Energy Systems | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	11.5
Parent Company | WGL Midstream | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	327.4
Parent Company | Other Non-Utility | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	2
Parent Company | Other External Partners | Performance guarantee
Commitments And Contingencies [Line Items]
Financial guarantees	18.9
WGL Midstream
Commitments And Contingencies [Line Items]
Losses associated with contract dispute	$ 8.8

Pension and Other Post-Retire63

Pension and Other Post-Retirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Amortization period regulatory assets liabilities-net	5 years	5 years	5 years	5 years
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3.6	$ 3.9	$ 10.7	$ 11.6
Interest cost	10.3	9.7	31	29.3
Expected return on plan assets	(10.2)	(11.2)	(30.7)	(33.5)
Amortization of prior service cost (credit)	0	0.1	0.2	0.2
Amortization of net actuarial loss	4.3	4.7	12.7	14.1
Net periodic benefit cost (income)	8	7.2	23.9	21.7
Amount allocated to construction projects	(1.5)	(1.2)	(4.1)	(3.4)
Amortization of regulatory asset (liability)-net	1.8	1.8	5.3	5.3
Amount charged (credited) to expense	8.3	7.8	25.1	23.6
Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.2	1.8	3.4	5.3
Interest cost	3.2	3.7	9.8	11
Expected return on plan assets	(5.1)	(5.2)	(15.3)	(15.6)
Amortization of prior service cost (credit)	(4.4)	(3.8)	(13.2)	(11.4)
Amortization of net actuarial loss	0.3	1.1	0.9	3.3
Net periodic benefit cost (income)	(4.8)	(2.4)	(14.4)	(7.4)
Amount allocated to construction projects	1.1	0.5	3	1.5
Amortization of regulatory asset (liability)-net	(0.1)	(0.1)	(0.2)	(0.2)
Amount charged (credited) to expense	$ (3.8)	$ (2)	$ (11.6)	$ (6.1)

Accumulated Other Comprehensi64

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
AOCI, Net of Tax [Roll Forward]
Beginning Balance		$ (24,258)	$ (11,643)	$ (14,236)	$ (7,961)
Qualified cash flow hedging instruments	[1]	(16,995)	49	(34,545)	(7,994)
Amortization of net prior service credit	[2]	(216)	(170)	(644)	(511)
Amortization of net actuarial loss	[2]	420	529	1,258	1,503
Current-period other comprehensive income (loss)		(16,791)	408	(33,931)	(7,002)
Income tax expense (benefit) related to other comprehensive income (loss)		(6,969)	163	(14,087)	(3,565)
Ending Balance		(34,080)	(11,398)	(34,080)	(11,398)
Washington Gas Light Company
AOCI, Net of Tax [Roll Forward]
Beginning Balance		(6,464)	(6,031)	(6,712)	(6,413)
Amortization of net prior service credit	[3]	(216)	(170)	(644)	(511)
Amortization of net actuarial loss	[3]	420	529	1,258	1,503
Current-period other comprehensive income (loss)		204	359	614	992
Income tax expense (benefit) related to other comprehensive income (loss)		82	143	244	394
Ending Balance		$ (6,342)	$ (5,815)	$ (6,342)	$ (5,815)
[1]	Cash flow hedging instruments represent interest rate swap agreements related to future debt issuances. Refer to Note 8- Derivative and Weather-related Instruments for further discussion of the interest rate swap agreements.
[2]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14- Pension and other post-retirement benefit plans for additional details.
[3]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 14-Pension and other post-retirement benefit plans for additional details.