Washington Gas Light (WGLCP) 10-Q 5 Feb 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2015	Jan. 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	Dec. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		49,847,937
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	Dec. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--09-30
Entity Filer Category	Non-accelerated Filer

Balance Sheets (Unaudited)

Balance Sheets (Unaudited) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Property, Plant and Equipment
At original cost	$ 5,090,450	$ 5,003,910
Accumulated depreciation and amortization	(1,343,829)	(1,331,182)
Net property, plant and equipment	3,746,621	3,672,728
Current Assets
Cash and cash equivalents	15,778	6,733
Receivables
Accounts receivable	307,717	276,358
Gas costs and other regulatory assets	21,094	5,797
Unbilled revenues	144,148	102,560
Allowance for doubtful accounts	(23,924)	(26,224)
Net receivables	449,035	358,491
Materials and supplies—principally at average cost	21,282	21,402
Storage gas	212,969	211,443
Prepaid taxes	67,533	48,726
Other prepayments	58,915	32,850
Derivatives	22,019	22,933
Assets held for sale	22,906	22,906
Other	47,559	23,057
Total current assets	917,996	748,541
Regulatory assets
Gas costs	172,802	190,676
Pension and other post-retirement benefits	206,153	212,041
Other	84,791	80,018
Prepaid post-retirement benefits	144,484	138,629
Derivatives	29,735	32,132
Investments in direct financing leases, capital leases	34,751	35,234
Investments in unconsolidated affiliates	145,183	136,884
Other	17,739	14,476
Total deferred charges and other assets	835,638	840,090
Total Assets	5,500,255	5,261,359
Capitalization
Common shareholders’ equity	1,289,102	1,243,247
Washington Gas Light Company preferred stock	28,173	28,173
Long-term debt	945,582	944,201
Total capitalization	2,262,857	2,215,621
Current Liabilities
Current maturities of long-term debt	25,000	25,000
Notes payable	527,875	332,000
Accounts payable and other accrued liabilities	309,339	325,146
Wages payable	19,689	21,091
Accrued interest	13,327	7,835
Dividends declared	23,378	23,377
Customer deposits and advance payments	94,796	88,897
Gas costs and other regulatory liabilities	36,401	34,551
Accrued taxes	20,508	13,867
Derivatives	67,117	63,504
Liabilities held for sale	1,621	1,621
Other	41,898	46,025
Total current liabilities	1,180,949	982,914
Deferred Credits
Unamortized investment tax credits	148,216	135,673
Deferred income taxes	713,585	672,963
Accrued pensions and benefits	179,920	176,128
Asset retirement obligations	206,037	200,732
Regulatory liabilities
Accrued asset removal costs	320,250	325,496
Other post-retirement benefits	100,986	104,382
Other	16,823	17,067
Derivatives	261,760	322,259
Other	108,872	108,124
Total deferred credits	$ 2,056,449	$ 2,062,824
Commitments and Contingencies (Note 13)
Total Capitalization and Liabilities	$ 5,500,255	$ 5,261,359
Washington Gas Light Company
Property, Plant and Equipment
At original cost	4,574,364	4,521,535
Accumulated depreciation and amortization	(1,286,614)	(1,278,089)
Net property, plant and equipment	3,287,750	3,243,446
Current Assets
Cash and cash equivalents	1	1
Receivables
Accounts receivable	165,696	126,356
Gas costs and other regulatory assets	21,094	5,797
Unbilled revenues	60,260	21,027
Allowance for doubtful accounts	(17,012)	(19,254)
Net receivables	230,038	133,926
Materials and supplies—principally at average cost	21,236	21,356
Storage gas	89,013	94,489
Prepaid taxes	67,808	30,365
Other prepayments	21,377	11,899
Receivables from associated companies	4,469	3,176
Derivatives	6,058	4,588
Assets held for sale	22,906	22,906
Total current assets	462,906	322,706
Regulatory assets
Gas costs	172,802	190,676
Pension and other post-retirement benefits	204,951	210,811
Other	84,720	79,946
Prepaid post-retirement benefits	143,605	137,754
Derivatives	14,333	13,155
Other	6,826	5,638
Total deferred charges and other assets	627,237	637,980
Total Assets	4,377,893	4,204,132
Capitalization
Common shareholders’ equity	1,115,648	1,081,292
Washington Gas Light Company preferred stock	28,173	28,173
Long-term debt	697,243	695,885
Total capitalization	1,841,064	1,805,350
Current Liabilities
Current maturities of long-term debt	25,000	25,000
Notes payable	207,475	89,000
Accounts payable and other accrued liabilities	138,218	159,280
Wages payable	18,200	19,456
Accrued interest	11,802	4,023
Dividends declared	20,263	20,269
Customer deposits and advance payments	94,048	88,450
Gas costs and other regulatory liabilities	36,401	34,551
Accrued taxes	16,780	11,659
Payables to associated companies	82,267	68,623
Derivatives	23,981	33,856
Liabilities held for sale	1,621	1,621
Other	7,026	7,013
Total current liabilities	683,082	562,801
Deferred Credits
Unamortized investment tax credits	5,443	5,646
Deferred income taxes	734,869	668,764
Accrued pensions and benefits	178,090	174,318
Asset retirement obligations	201,262	198,938
Regulatory liabilities
Accrued asset removal costs	320,250	325,496
Other post-retirement benefits	100,316	103,683
Other	16,823	17,067
Derivatives	228,549	269,661
Other	68,145	72,408
Total deferred credits	$ 1,853,747	$ 1,835,981
Commitments and Contingencies (Note 13)
Total Capitalization and Liabilities	$ 4,377,893	$ 4,204,132

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
OPERATING REVENUES
Utility		$ 288,153	$ 381,712
Non-utility		325,231	367,525
Total Operating Revenues	[1]	613,384	749,237
OPERATING EXPENSES
Utility cost of gas		50,025	129,704
Non-utility cost of energy-related sales		282,487	336,568
Operation and maintenance		95,419	92,380
Depreciation and Amortization		31,412	29,360
General taxes and other assessments		36,532	39,383
Total Operating Expenses		495,875	627,395
OPERATING INCOME		117,509	121,842
Equity in Earnings of Unconsolidated Affiliates		1,263	1,144
Other income (expenses)—net		979	(4,355)
Interest expense		12,760	12,310
INCOME BEFORE INCOME TAXES		106,991	106,321
INCOME TAX EXPENSE		38,490	42,103
NET INCOME		68,501	64,218
Dividends on Washington Gas Light Company preferred stock		330	330
NET INCOME APPLICABLE TO COMMON STOCK		$ 68,171	$ 63,888
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Basic (in shares)		49,807	49,946
Diluted (in shares)		50,030	50,091
EARNINGS PER AVERAGE COMMON SHARE
Basic (in dollars per share)		$ 1.37	$ 1.28
Diluted (in dollars per share)		1.36	1.28
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)		$ 0.4625	$ 0.44
Washington Gas Light Company
OPERATING REVENUES
Utility		$ 295,246	$ 387,193
OPERATING EXPENSES
Utility cost of gas		57,118	135,165
Operation and maintenance		79,308	74,957
Depreciation and Amortization		27,205	26,604
General taxes and other assessments		32,638	35,844
Total Operating Expenses		196,269	272,570
OPERATING INCOME		98,977	114,623
Other income (expenses)—net		(220)	(450)
Interest expense		10,323	10,264
INCOME BEFORE INCOME TAXES		88,434	103,909
INCOME TAX EXPENSE		33,822	38,958
NET INCOME		54,612	64,951
Dividends on Washington Gas Light Company preferred stock		330	330
NET INCOME APPLICABLE TO COMMON STOCK		$ 54,282	$ 64,621
[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
	Dec. 31, 2015		Dec. 31, 2014
Net Income (Loss)	$ 68,501		$ 64,218
OTHER COMPREHENSIVE INCOME, BEFORE INCOME TAXES:
Qualified cash flow hedging instruments	1,084	[1]	(8,265)
Pension and other post-retirement benefit plans
Change in net prior service credit	(214)	[2]	(171)
Change in actuarial net loss	419	[2]	484
Total pension and other post-retirement benefit plans	205		313
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME	531		(3,947)
OTHER COMPREHENSIVE INCOME (LOSS)	758		(4,005)
COMPREHENSIVE INCOME	69,259		60,213
Washington Gas Light Company
Net Income (Loss)	54,612		64,951
Pension and other post-retirement benefit plans
Change in net prior service credit	(214)	[2]	(171)
Change in actuarial net loss	419	[2]	484	[3]
Total pension and other post-retirement benefit plans	205		313
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME	81		124
OTHER COMPREHENSIVE INCOME (LOSS)	124		189
COMPREHENSIVE INCOME	$ 54,736		$ 65,140
[1]	Cash flow hedging instruments represent interest rate swap agreements related to 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	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
OPERATING ACTIVITIES
Net income	$ 68,501	$ 64,218
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and Amortization	31,412	29,360
Amortization of:
Other regulatory assets and liabilities—net	325	327
Debt related costs	316	240
Deferred income taxes—net	78,038	62,774
Accrued/deferred pension and other post-retirement benefit cost	4,944	4,776
Compensation expense related to stock-based awards	3,549	338
Provision for doubtful accounts	2,533	3,575
Impairment loss	0	5,625
Other non-cash charges (credits)—net	380	2,139
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable and unbilled revenues—net	(77,780)	(226,539)
Gas costs and other regulatory assets/liabilities—net	(13,447)	40,397
Storage gas	(1,526)	36,691
Prepaid taxes	(18,807)	18,765
Other prepayments	(26,065)	1,164
Accounts payable and other accrued liabilities	(11,416)	51,648
Customer deposits and advance payments	5,899	10,355
Unamortized investment tax credits	12,543	15,071
Accrued taxes	6,641	13,302
Accrued interest	5,492	10,139
Other current assets	(25,772)	(13,803)
Other current liabilities	(7,369)	12,136
Deferred gas costs—net	17,874	(3,632)
Deferred assets—other	(12,097)	(2,551)
Deferred liabilities—other	(49,681)	(65,185)
Derivatives	(52,490)	(59,955)
Other—net	(82)	317
Net Cash (Used in) Provided by Operating Activities	(58,085)	11,692
FINANCING ACTIVITIES
Common stock issued	83	0
Long-term debt issued	0	296,481
Debt issuance costs	(135)	(2,443)
Notes payable issued (retired) —net	195,875	(103,500)
Dividends on common stock and preferred stock	(23,377)	(22,449)
Repurchase of common stock	0	(41,485)
Other financing activities—net	2,006	0
Net Cash Provided by Financing Activities	174,452	126,604
INVESTING ACTIVITIES
Capital expenditures (excluding AFUDC)	(101,013)	(132,954)
Investments in non-utility interests	(8,374)	(8,059)
Distributions from non-utility interests	2,065	1,296
Net Cash Used in Investing Activities	(107,322)	(139,717)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	9,045	(1,421)
Cash and Cash Equivalents at Beginning of Year	6,733	8,811
Cash and Cash Equivalents at End of Period	15,778	7,390
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid—net	1,615	880
Interest paid	7,190	1,839
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Project debt financing activities—net	1,356	(2,032)
Capital expenditure accruals included in accounts payable and other accrued liabilities	39,140	24,649
Dividends paid in common stock	0	1,306
Stock issued related to compensation	5,947	0
Washington Gas Light Company
OPERATING ACTIVITIES
Net income	54,612	64,951
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and Amortization	27,205	26,604
Amortization of:
Other regulatory assets and liabilities—net	325	164
Debt related costs	293	339
Deferred income taxes—net	58,522	54,492
Accrued/deferred pension and other post-retirement benefit cost	5,615	4,751
Compensation expense related to stock-based awards	3,350	2,305
Provision for doubtful accounts	1,997	2,800
Other non-cash charges (credits)—net	1,494	2,564
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable and unbilled revenues—net	(84,105)	(179,268)
Gas costs and other regulatory assets/liabilities—net	(13,447)	40,397
Storage gas	5,476	6,003
Prepaid taxes	(37,443)	(7,867)
Other prepayments	(9,478)	2,554
Accounts payable and other accrued liabilities	4,154	37,765
Customer deposits and advance payments	5,598	10,214
Accrued taxes	5,121	(2,612)
Accrued interest	7,779	8,628
Other current assets	120	(733)
Other current liabilities	(3,154)	376
Deferred gas costs—net	17,874	(3,632)
Deferred assets—other	(10,541)	(3,404)
Deferred liabilities—other	(4,461)	(3,074)
Derivatives	(53,635)	(57,063)
Other—net	(10)	191
Net Cash (Used in) Provided by Operating Activities	(16,739)	7,445
FINANCING ACTIVITIES
Long-term debt issued	0	50,000
Debt issuance costs	(135)	(672)
Notes payable issued (retired) —net	118,475	49,000
Dividends on common stock and preferred stock	(20,269)	(19,722)
Other financing activities—net	1,949	0
Net Cash Provided by Financing Activities	100,020	78,606
INVESTING ACTIVITIES
Capital expenditures (excluding AFUDC)	(83,281)	(87,110)
Net Cash Used in Investing Activities	(83,281)	(87,110)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	0	(1,059)
Cash and Cash Equivalents at Beginning of Year	1	1,060
Cash and Cash Equivalents at End of Period	1	1
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid—net	0	700
Interest paid	4,753	1,304
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Project debt financing activities—net	1,356	(2,032)
Capital expenditure accruals included in accounts payable and other accrued liabilities	$ 28,073	$ 17,734

Accounting Policies

Accounting Policies	3 Months Ended
	Dec. 31, 2015
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), Hampshire Gas Company (Hampshire) and Crab Run Gas Company (Crab Run). 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 . 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. Certain prior period amounts 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 . Assets Held for Sale At December 31, 2015 , the Springfield Operations Center met the criteria to be reported as held for sale. Those criteria specify that (a) the asset must be available for immediate sale in its present condition subject only to terms that are usual and customary for sales of such assets and (b) the sale of the asset must be probable, and its transfer expected to qualify for recognition as a completed sale, within one year, with certain exceptions. At December 31, 2015 and September 30, 2015 , the assets and liabilities associated with the Springfield Operations Center are 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. Storage Gas Valuations For Washington Gas and WGL Energy Services, storage gas inventories are stated at the lower-of-cost or market as determined using the first-in, first-out method. For WGL Midstream, storage gas inventory is stated at the lower-of-cost or market using the weighted average cost method. 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 months ended December 31, 2015 and 2014 . Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income Three Months Ended December 31, (In millions) 2015 2014 WGL (a) Operating revenues - non-utility $ (1.9 ) $ (17.5 ) Washington Gas Utility cost of gas — (0.7 ) Total Consolidated $ (1.9 ) $ (18.2 ) (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 Date of adoption Effect on the financial statements or other significant matters 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, 2019 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 permits prospective or retrospective application. An entity can defer and present debt issuance costs related to to line-of-credit arrangements as an asset and subsequently amortizing 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. ASU 2014-09 and ASU 2015-14, Revenue from Contracts with Customers (Topic 606) and Deferral of the Effective Date. The standard 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. The standard permits retrospective application. October 1, 2019 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	3 Months Ended
	Dec. 31, 2015
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) December 31, 2015 September 30, 2015 Accounts payable—trade $ 261.6 $ 277.3 Employee benefits and payroll accruals 19.2 31.4 Other accrued liabilities 28.5 16.4 Total $ 309.3 $ 325.1 Washington Gas Light Company (In millions) December 31, 2015 September 30, 2015 Accounts payable—trade $ 108.8 $ 122.2 Employee benefits and payroll accruals 18.2 29.5 Other accrued liabilities 11.2 7.6 Total $ 138.2 $ 159.3

Short-Term Debt

Short-Term Debt	3 Months Ended
	Dec. 31, 2015
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 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 December 31, 2015 and September 30, 2015 . Committed Credit Available (In millions) December 31, 2015 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 (320.4 ) (207.5 ) (527.9 ) Net committed credit available $ 129.6 $ 142.5 $ 272.1 Weighted average interest rate 0.55 % — 0.42 % 0.50 % 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 December 31, 2015 and September 30, 2015 , there were no outstanding bank loans from WGL’s or Washington Gas’ revolving credit facilities.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Dec. 31, 2015
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 December 31, 2015 and September 30, 2015 , WGL had the capacity under a shelf registration to issue an unspecified amount of long-term debt securities. At December 31, 2015 and September 30, 2015 Washington Gas had the capacity under a shelf registration statement to issue up to $600.0 million of additional Medium-Term Notes (MTNs). The following tables show the outstanding notes as of December 31, 2015 and September 30, 2015 . Long-Term Debt Outstanding ($ In millions) WGL (a) Washington Gas Total Consolidated December 31, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 Weighted average interest rate 3.66 % 5.58 % 5.08 % September 30, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 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 for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities. There were no issuances or retirements for the three months ended December 31, 2015 . The following tables show long-term debt issuances for the three months ended December 31, 2014 . There were no retirements for WGL or Washington Gas for the three months ended December 31, 2014 . Long-Term Debt Issuances ($ In millions) Principal (b) Interest Rate Effective Cost (c) Nominal Maturity Date Three Months Ended December 31, 2014 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 for WGL and both MTNs and private placement notes for Washington Gas. (c) The estimated effective cost of the issued notes, including consideration of issuance fees and hedge costs.

Common Shareholders' Equity

Common Shareholders' Equity	3 Months Ended
	Dec. 31, 2015
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 three months ended December 31, 2015 . WGL Holdings, Inc. Components of Common Shareholders’ Equity (In thousands) Common Stock Amount Paid-In Capital Retained Earnings Accumulated Other Comprehensive Income (Loss), Net of Taxes Total Balance at September 30, 2015 $ 485,456 $ 14,934 $ 757,093 $ (14,236 ) $ 1,243,247 Net income — — 68,501 — 68,501 Other comprehensive income — — — 758 758 Stock-based compensation (a) 5,947 (6,016 ) (40 ) — (109 ) Issuance of common stock 83 — — — 83 Dividends declared: Common stock — — (23,048 ) — (23,048 ) Preferred stock — — (330 ) — (330 ) Balance at December 31, 2015 $ 491,486 $ 8,918 $ 802,176 $ (13,478 ) $ 1,289,102 (a) Includes dividend equivalents related to our performance shares. Washington Gas Light Company Components of Common Shareholder’s Equity (In thousands) Common Stock Amount Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss, Net of Taxes Total Balance at September 30, 2015 $ 46,479 $ 483,677 $ 557,848 $ (6,712 ) $ 1,081,292 Net income — — 54,612 — 54,612 Other comprehensive loss — — — 124 124 Stock-based compensation — (117 ) — — (117 ) Dividends declared: Common stock — — (19,933 ) — (19,933 ) Preferred stock — — (330 ) — (330 ) Balance at December 31, 2015 $ 46,479 $ 483,560 $ 592,197 $ (6,588 ) $ 1,115,648 WGL had 49,833,349 and 49,728,662 shares issued of common stock at December 31, 2015 and September 30, 2015 , respectively. Washington Gas had 46,479,536 shares issued of common stock at both December 31, 2015 and September 30, 2015 .

Earnings Per Share

Earnings Per Share	3 Months Ended
	Dec. 31, 2015
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 months ended December 31, 2015 and 2014 . Basic and Diluted EPS (in thousands, except per share data) Net Income Applicable to Common Stock Shares Per Share Amount Three Months Ended December 31, 2015 Basic EPS $ 68,171 49,807 $ 1.37 Stock-based compensation plans — 223 Diluted EPS $ 68,171 50,030 $ 1.36 Three Months Ended December 31, 2014 Basic EPS $ 63,888 49,946 $ 1.28 Stock-based compensation plans — 145 Diluted EPS $ 63,888 50,091 $ 1.28 For the three months ended December 31, 2015 , 76,000 performance shares issuable pursuant to our stock-based compensation plans, were not considered in the diluted share calculation due to the anti-dilutive effect of such shares. There were no anti-dilutive shares for the three months ended December 31, 2014 .

Income Taxes

Income Taxes	3 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES As of December 31, 2015 and September 30, 2015 , our uncertain tax positions were approximately $35.6 million and $38.6 million , respectively, 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 December 31, 2015 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. Effective 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 presently 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 our retrospective adoption, $32.8 million and $24.7 million for WGL and Washington Gas, respectively, was reclassified from "Current Assets-Deferred income taxes" to "Deferred Credits-Deferred income taxes" on our September 30, 2015 balance sheets.

Derivative and Weather Related

Derivative and Weather Related Instruments	3 Months Ended
	Dec. 31, 2015
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 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 derivatives used under this program are subject to mark-to-market accounting treatment while the capacity and transportation resources are not. Regulatory sharing mechanisms allow the profits or losses from these transactions to be shared between Washington Gas' shareholders and customers; therefore, any changes in fair value are recorded through earnings, or as regulatory assets or liabilities to the extent that gains and losses associated with these derivative instruments will be included in the rates charged to customers when they are realized. Valuation changes for the portion of net profits or losses to be retained for shareholders may cause significant period-to-period volatility in earnings from unrealized gains and losses. 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 December 31, 2015 was a net gain of $26.8 million including an unrealized gain of $19.4 million . During the three months ended December 31, 2014 we recorded a gain of $31.1 million including an unrealized gain of $25.0 million . Managing Price Risk. To manage price risk associated with acquiring natural gas supply for utility customers, Washington Gas enters into forward contracts, option contracts, financial contracts and other contracts, as authorized by its regulators. These instruments are accounted for as derivative instruments. 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 newly issued debt. 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. The storage and transportation capacity utilized by WGL Midstream are not considered to be derivative instruments, and thus they are not recorded at fair value on our consolidated balance sheets. Managing Price Risk. WGL Energy Services enters into certain derivative contracts as part of managing 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 minimize the risk of interest-rate volatility associated with future debt issuances. In August 2015, WGL entered into two forward starting interest rate swap agreements, with a total notional amount of $125.0 million , and designated them as cash flow hedges in accordance with ASC 815. These derivatives hedge the variability in future interest payments due to changes in interest rates prior to WGL's expected issuance of 30-year debt in January 2018. The effective portion of changes in the fair value of qualified derivatives designated as cash flow hedges is recorded in accumulated other comprehensive income (loss) and subsequently reclassified into earnings in the period that the hedged forecasted transactions affects earnings. Any ineffective portion of these derivatives will be recognized directly through earnings as interest expense. Additionally, WGL elected cash flow hedge accounting for interest rate derivative instruments, 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 and are being amortized over the life of the debt (through 2044). The amortization will be minimal for 2016 . 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 December 31, 2015 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 December 31, 2015 Notional Amounts Natural Gas (In millions of therms) Asset Optimization 21,553.3 13,148.3 Retail sales 57.0 — Other risk-management activities 1,909.4 1,372.1 Electricity (In millions of kWhs) Retail sales 4,758.2 — Other risk-management activities 21,578.8 — Interest Rate Swaps (In millions of dollars) $ 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 19,965.7 — Interest Rate Swaps (In millions of dollars) $ 125.0 $ — The following tables present the balance sheet classification for all derivative instruments as of December 31, 2015 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 December 31, 2015 Gross Derivative Assets Gross Derivative Liabilities Gross Derivative Assets Gross Derivative Liabilities Netting of Collateral Total (a) Current Assets—Derivatives $ 22.9 $ (0.9 ) $ — $ — $ — $ 22.0 Deferred Charges and Other Assets—Derivatives 29.9 (0.2 ) — — — 29.7 Current Liabilities—Derivatives 18.3 (100.7 ) — — 15.3 (67.1 ) Deferred Credits—Derivatives 7.6 (276.2 ) — (2.3 ) 9.1 (261.8 ) Total $ 78.7 $ (378.0 ) $ — $ (2.3 ) $ 24.4 $ (277.2 ) 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 December 31, 2015 Gross Gross Netting of Total (a) Current Assets—Derivatives $ 6.5 $ (0.4 ) $ — $ 6.1 Deferred Charges and Other Assets—Derivatives 14.5 (0.2 ) — 14.3 Current Liabilities—Derivatives 5.0 (30.9 ) 1.9 (24.0 ) Deferred Credits—Derivatives — (228.5 ) — (228.5 ) Total $ 26.0 $ (260.0 ) $ 1.9 $ (232.1 ) 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 December 31, 2015 or September 30, 2015 . The following table presents all gains and losses associated with derivative instruments for the three months ended December 31, 2015 and 2014 . Gains and Losses on Derivative Instruments (In millions) WGL Holdings, Inc. Washington Gas Three Months Ended December 31, 2015 2014 2015 2014 Recorded to income Operating revenues—non-utility $ 25.7 $ 75.4 $ — $ — Utility cost of gas 21.4 25.8 21.4 25.8 Non-utility cost of energy-related sales 7.5 (49.6 ) — — Interest expense — (0.4 ) — — Recorded to regulatory assets Gas costs 34.8 28.2 34.8 28.2 Recorded to other comprehensive income (a) 1.1 (8.2 ) — — Total $ 90.5 $ 71.2 $ 56.2 $ 54.0 (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. At December 31, 2015 , Washington Gas, WGL Energy Services and WGL Midstream posted $8.6 million , $24.1 million and $8.9 million , respectively, of collateral deposits with counterparties that were not offset against open and settled derivative contracts. At September 30, 2015 , Washington Gas, WGL Energy Services and WGL Midstream posted $3.5 million , $12.4 million and $3.5 million , respectively, of collateral deposits with counterparties that were not offset against open and settled derivative contracts. At December 31, 2015 , Washington Gas and WGL Midstream held $0.4 million and $0.7 million , respectively, of cash collateral representing an obligation to counterparties that was not offset against open and settled derivative contracts. At September 30, 2015 , Washington Gas and WGL Midstream held $3.8 million and $0.4 million , respectively of cash collateral representing an obligation to counterparties that was not offset against open and settled derivative contracts. Any collateral posted that is not offset against open and settled derivative contracts is included in “Other prepayments” in the accompanying balance sheets. Collateral received and not offset against open and settled derivative contracts is included in “Customer deposits and advance payments” in the accompanying balance sheets. Certain derivative instruments of 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 Energy Services or WGL Midstream exceeds a certain level. Due to counterparty exposure levels, at December 31, 2015 , WGL Energy Services posted $16.9 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. Washington Gas and WGL Midstream were not required to post any collateral related to their respective derivative liabilities that contained credit-related contingent features at December 31, 2015 or September 30, 2015 . 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 December 31, 2015 and September 30, 2015 , respectively. Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features (In millions) WGL Holdings, Inc. Washington Gas December 31, 2015 Derivative liabilities with credit-risk-contingent features $ 63.5 $ 17.1 Maximum potential collateral requirements 53.6 15.0 September 30, 2015 Derivative liabilities with credit-risk-contingent features $ 61.7 $ 18.9 Maximum potential collateral requirements 54.6 18.8 Washington Gas, WGL Energy Services and WGL Midstream 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 December 31, 2015 , two counterparties represented over 10% of Washington Gas’ credit exposure to wholesale derivative counterparties for a total credit risk of $19.1 million ; three counterparties represented over 10% of WGL Energy Services’ credit exposure to wholesale counterparties for a total credit risk of $1.0 million ; and one counterparty represented over 10% of WGL Midstream’s credit exposure to wholesale counterparties for a total credit risk of $13.5 million . WEATHER-RELATED INSTRUMENTS Washington Gas did not use any weather-related instruments during the three months ended December 31, 2015 and 2014 . 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 December 31, 2015 and 2014 , WGL Energy Services recorded a pre-tax gain of $6.0 million and a pre-tax loss of $1.7 million , respectively, related to these contracts.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Dec. 31, 2015
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 December 31, 2015 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 December 31, 2015 and September 30, 2015 , Level 2 financial assets and liabilities included energy-related derivatives such as financial contracts, options and physical forward contracts for deliveries at active market locations, as well as our interest rate hedges. 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 December 31, 2015 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 December 31, 2015 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 December 31, 2015 Assets Natural gas related derivatives $ — $ 25.3 $ 35.7 $ 61.0 Electricity related derivatives — 2.2 15.5 17.7 Total Assets $ — $ 27.5 $ 51.2 $ 78.7 Liabilities Natural gas related derivatives $ — $ (56.1 ) $ (279.3 ) $ (335.4 ) Electricity related derivatives — (2.7 ) (39.9 ) (42.6 ) Interest rate derivatives — (2.3 ) — (2.3 ) Total Liabilities $ — $ (61.1 ) $ (319.2 ) $ (380.3 ) 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 December 31, 2015 Assets Natural gas related derivatives $ — $ 12.8 $ 13.2 $ 26.0 Total Assets $ — $ 12.8 $ 13.2 $ 26.0 Liabilities Natural gas related derivatives $ — $ (24.7 ) $ (235.3 ) $ (260.0 ) Total Liabilities $ — $ (24.7 ) $ (235.3 ) $ (260.0 ) 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 December 31, 2015 and September 30, 2015 . Quantitative Information about Level 3 Fair Value Measurements (In millions) Net Fair Value Valuation Techniques Unobservable Inputs Range WGL Holdings, Inc. Natural gas related derivatives $(243.6) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.147) - $3.148 Option Model Natural Gas Basis Price (per dekatherm) ($0.183) - $3.208 Annualized Volatility of Spot Market Natural Gas 25.0% - 755.3% Electricity related derivatives $(24.4) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($6.32) - $71.75 Washington Gas Light Company Natural gas related derivatives $(222.1) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.147) - $2.250 Net Fair Value 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 months ended December 31, 2015 and 2014 , 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 December 31, 2015 Balance at October 1, 2015 $ (309.7 ) $ (16.0 ) $ (325.7 ) Realized and unrealized gains (losses) Recorded to income 22.8 (22.3 ) 0.5 Recorded to regulatory assets—gas costs 29.6 — 29.6 Transfers into Level 3 (0.9 ) — (0.9 ) Transfers out of Level 3 8.9 — 8.9 Purchases — 6.4 6.4 Settlements 5.7 7.5 13.2 Balance at December 31, 2015 $ (243.6 ) $ (24.4 ) $ (268.0 ) Three Months Ended December 31, 2014 Balance at October 1, 2014 $ (294.7 ) $ (5.0 ) $ (299.7 ) Realized and unrealized gains (losses) Recorded to income 20.3 (10.9 ) 9.4 Recorded to regulatory assets—gas costs 13.6 — 13.6 Transfers out of Level 3 (1.7 ) — (1.7 ) Purchases — 3.2 3.2 Settlements 9.9 1.2 11.1 Balance at December 31, 2014 $ (252.6 ) $ (11.5 ) $ (264.1 ) Washington Gas Light Company Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs (In millions) Natural Gas Related Derivatives Three Months Ended December 31, 2015 Balance at October 1, 2015 $ (281.1 ) Realized and unrealized gains (losses) Recorded to income 17.0 Recorded to regulatory assets—gas costs 29.6 Transfers into Level 3 (0.2 ) Transfers out of Level 3 8.8 Settlements 3.8 Balance at December 31, 2015 $ (222.1 ) Three Months Ended December 31, 2014 Balance at October 1, 2014 $ (270.6 ) Realized and unrealized gains (losses) Recorded to income 14.7 Recorded to regulatory assets—gas costs 13.6 Transfers out of Level 3 (1.7 ) Settlements 9.2 Balance at December 31, 2014 $ (234.8 ) Transfers between different levels of the fair value hierarchy may occur based 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 reporting period. Transfers out of Level 3 during the three months ended December 31, 2015 and 2014 were due to an increase in valuations using observable market inputs. Transfers into Level 3 during the three months ended December 31, 2015 were due to an increase in unobservable market inputs used in valuations. There were no transfers into Level 3 during the three months ended December 31, 2014 . The table below sets forth the line items on the statements of income to which amounts are recorded for the three months ended December 31, 2015 and 2014 , 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 December 31, 2015 Operating revenues—non-utility $ 9.5 $ (12.2 ) $ (2.7 ) Utility cost of gas 17.0 — 17.0 Non-utility cost of energy-related sales (3.7 ) (10.1 ) (13.8 ) Total $ 22.8 $ (22.3 ) $ 0.5 Three Months Ended December 31, 2014 Operating revenues—non-utility $ 10.5 $ 20.8 $ 31.3 Utility cost of gas 14.7 — 14.7 Non-utility cost of energy-related sales (4.9 ) (31.7 ) (36.6 ) Total $ 20.3 $ (10.9 ) $ 9.4 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 December 31, 2015 Utility cost of gas $ 17.0 Total $ 17.0 Three Months Ended December 31, 2014 Utility cost of gas $ 14.7 Total $ 14.7 Unrealized gains (losses) attributable to derivative assets and liabilities measured using significant Level 3 inputs were recorded as follows, for the three months ended December 31, 2015 and 2014 , 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 December 31, 2015 Recorded to income Operating revenues—non-utility $ 11.3 $ (5.0 ) $ 6.3 Utility cost of gas 15.9 — 15.9 Non-utility cost of energy-related sales (4.4 ) (3.6 ) (8.0 ) Recorded to regulatory assets—gas costs 27.0 — 27.0 Total $ 49.8 $ (8.6 ) $ 41.2 Three Months Ended December 31, 2014 Recorded to income Operating revenues—non-utility $ 11.9 $ 20.8 $ 32.7 Utility cost of gas 14.8 — 14.8 Non-utility cost of energy-related sales (5.5 ) (27.1 ) (32.6 ) Recorded to regulatory assets—gas costs 18.5 — 18.5 Total $ 39.7 $ (6.3 ) $ 33.4 Washington Gas Light Company Unrealized Gains (Losses) Recorded for Level 3 Measurements (In millions) Natural Gas Related Derivatives Three Months Ended December 31, 2015 Recorded to income - utility cost of gas $ 15.9 Recorded to regulatory assets—gas costs 27.0 Total $ 42.9 Three Months Ended December 31, 2014 Recorded to income - utility cost of gas $ 14.8 Recorded to regulatory assets—gas costs 18.5 Total $ 33.3 The following table presents the carrying amounts and estimated fair values of our financial instruments at December 31, 2015 and September 30, 2015 . WGL Holdings, Inc. Fair Value of Financial Instruments December 31, 2015 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 21.4 $ 21.4 $ 11.0 $ 11.0 Other short-term investments (a) $ 0.5 $ 0.5 $ 0.4 $ 0.4 Commercial paper (b) $ 527.9 $ 527.9 $ 332.0 $ 332.0 Long-term debt (c) $ 945.6 $ 1,028.5 $ 944.2 $ 1,057.9 Washington Gas Light Company Fair Value of Financial Instruments December 31, 2015 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 5.7 $ 5.7 $ 4.3 $ 4.3 Other short-term investments (a) $ 0.5 $ 0.5 $ 0.4 $ 0.4 Commercial paper (b) $ 207.5 $ 207.5 $ 89.0 $ 89.0 Long-term debt (c) $ 697.2 $ 789.3 $ 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) Less current maturities and unamortized discounts. Our money market funds are Level 1 valuations and their carrying amount approximates fair value. Other short-term investments are primarily overnight investment accounts; therefore, their carrying amount approximates fair value based on Level 2 inputs. The maturity of our commercial paper outstanding at both December 31, 2015 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. 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 three months ended December 31, 2014 , 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	3 Months Ended
	Dec. 31, 2015
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 months ended December 31, 2015 and 2014 . 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 December 31, 2015 Regulated utility $ 295,246 $ 27,595 $ — $ 99,289 $ 4,400,622 $ 83,561 $ — Retail energy-marketing 289,395 306 — (567 ) 482,780 430 — Commercial energy systems 15,622 3,481 394 943 729,312 17,022 62,618 Midstream energy services 21,210 35 869 20,839 258,013 — 82,565 Other activities — — — (780 ) 273,819 — — Eliminations (b) (8,089 ) (5 ) — 27 (644,291 ) — — Total consolidated $ 613,384 $ 31,412 $ 1,263 $ 119,751 $ 5,500,255 $ 101,013 $ 145,183 Three Months Ended December 31, 2014 Regulated utility $ 387,193 $ 26,952 $ — $ 114,627 $ 4,200,780 $ 89,603 $ — Retail energy-marketing 330,489 167 — (15,895 ) 436,204 34 — Commercial energy systems 9,539 2,235 577 259 544,682 43,317 66,100 Midstream energy services 28,092 31 536 26,771 249,789 — 36,167 Other activities — — 31 (7,099 ) 409,123 — 48 Eliminations (b) (6,076 ) (25 ) — (32 ) (692,486 ) — — Total consolidated $ 749,237 $ 29,360 $ 1,144 $ 118,631 $ 5,148,092 $ 132,954 $ 102,315 (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, 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 December 31, (In thousands) 2015 2014 Total consolidated EBIT $ 119,751 $ 118,631 Interest expense 12,760 12,310 Income before income taxes 106,991 106,321 Income tax expense 38,490 42,103 Net income 68,501 64,218 Dividends on Washington Gas Light Company preferred stock 330 330 Net income applicable to common stock $ 68,171 $ 63,888

Other Investments

Other Investments	3 Months Ended
	Dec. 31, 2015
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 to the entity, otherwise 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) and Mountain Valley Pipeline, LLC (Mountain Valley) 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 December 31, 2015 , 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). The 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 million for a 55% interest in 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 December 31, 2015 and September 30, 2015 , WGL Midstream held a $36.3 million and $30.5 million , respectively, equity method investment in Meade. Our maximum financial exposure includes contributions and guarantees on behalf of WGL Midstream. Our maximum exposure to loss at December 31, 2015 was $59.4 million , which represents the minimum funding requirements owed to Williams under the Construction and Ownership Agreement should Meade terminate its agreement with Williams early. SunEdison/Nextility WGSW is party to two agreements to fund residential and commercial retail solar energy installations with two separate companies. WGSW has a master purchase agreement and master lease agreement with SunEdison, Inc. (SunEdison) and 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 interest in the financing leases in “Other income (expenses)-net” line in the accompanying Consolidated Statements of Income. WGSW held a $36.5 million and $37.2 million combined investment in direct financing leases at December 31, 2015 and September 30, 2015 , respectively, of which $1.7 million and $2.0 million are current receivables recorded in “Accounts Receivable” in the accompanying Consolidated Balance Sheets at December 31, 2015 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 $ 2.2 2017 2.2 2018 2.2 2019 2.1 2020 2.2 Thereafter 30.7 Total $ 41.6 Minimum payments receivable exclude $9.7 million of residual values and $4.6 million in tax credits. Associated with these investments, WGSW holds $19.4 million of unearned income 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. 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. ASD In addition to SunEdison and Nextility, 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 a total of $72.6 million . 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 December 31, 2015 and September 30, 2015 , WGSW held a $62.6 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 December 31, 2015 , the carrying amount of WGSW’s investment in ASD exceeded the amount of the underlying equity in net assets by $35.9 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 three months ended December 31, 2014 , 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). WGL Midstream will invest an estimated aggregate amount of $83 million in the project for a 10% share in the pipeline venture over the term of the agreement. This natural gas pipeline venture will 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. WGL Midstream held a $36.3 million equity method investment in Constitution at December 31, 2015 . At December 31, 2015 , WGL Midstream's maximum financial exposure is limited to its contributions made to the partnership, which was a total of $31.8 million . Mountain Valley Pipeline 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, in 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 million. WGL Midstream held a $9.9 million equity method investment in Mountain Valley at December 31, 2015 . 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. Our maximum financial exposure includes guarantees on behalf of WGL Midstream and another partner in the venture. WGL's maximum exposure to loss due to the provided guarantees was $20.0 million at December 31, 2015 which represents a $14.0 million minimum funding requirement for WGL Midstream and the 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 $4.2 million as of December 31, 2015 related to this agreement. The balance sheet location of the investments discussed in this footnote at December 31, 2015 and September 30, 2015 are as follows: WGL Holdings, Inc. Balance Sheet Location of Other Investments As of December 31, 2015 (in millions) VIEs Non-VIEs Total Assets Investments in unconsolidated affiliates $ 98.9 $ 46.3 $ 145.2 Investments in direct financing leases, capital leases 34.8 — 34.8 Accounts receivable 1.7 4.2 (a) 5.9 Total assets $ 135.4 $ 50.5 $ 185.9 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 months ended December 31, 2015 and 2014 are as follows: WGL Holdings, Inc. Income Statement Location of Other Investments (In millions) VIEs Non-VIEs Total Three Months Ended December 31, 2015 Equity in earnings of unconsolidated affiliates $ 0.4 $ 0.9 $ 1.3 Depreciation and amortization 0.1 — 0.1 Other income—net 0.9 — 0.9 Net income $ 1.2 $ 0.9 $ 2.1 Three Months Ended December 31, 2014 Equity in earnings of unconsolidated affiliates $ 0.6 $ 0.5 $ 1.1 Depreciation and amortization 0.1 — 0.1 Other income (expenses)—net 0.6 (5.6 ) (5.0 ) Net income (loss) $ 1.1 $ (5.1 ) $ (4.0 )

Related Party Transactions

Related Party Transactions	3 Months Ended
	Dec. 31, 2015
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 yet 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 and with other miscellaneous billing processes, Washington Gas collects cash on behalf of affiliates and transfers the cash in a reasonable time period. Cash collected by Washington Gas on behalf of its affiliates but not yet transferred is recorded in “Payables to associated companies” on Washington Gas’ balance sheets. The following table presents the receivables and payables from associated companies as of December 31, 2015 and September 30, 2015 . Washington Gas Receivables / Payables from Associated Companies (In millions) December 31, 2015 September 30, 2015 Receivables from Associated Companies $ 4.5 $ 3.2 Payables to Associated Companies $ 82.3 $ 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 balance services. Washington Gas - Gas Balancing Service Charges Three Months Ended December 31, (In millions) 2015 2014 Gas balancing service charge $ 7.1 $ 5.5 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 $3.2 million and $0.5 million at December 31, 2015 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 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 December 31, 2015 and September 30, 2015 , Washington Gas had balances of $8.6 million and $6.6 million , respectively, of purchased receivables from WGL Energy Services.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Dec. 31, 2015
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. The following is an update on significant regulatory matters pending. 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’s application for reconsideration. The PSC of DC directed the parties to file initial briefs by February 18, 2016, and reply briefs by February 28, 2016, on the issue of whether a “fairer way” to reconcile the over-deliveries by CSPs is through volumetric adjustments, or through cash payments. FINANCIAL GUARANTEES WGL has guaranteed payments primarily for certain commitments on behalf of Washington Gas, WGL Energy Services, WGL Energy Systems and WGL Midstream. At December 31, 2015 , these guarantees totaled $30.7 million , $259.0 million , $8.6 million and $333.5 million for Washington Gas, WGL Energy Services, WGL Energy Systems and WGL Midstream, respectively. At December 31, 2015 , 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 December 31, 2015 , these guarantees totaled $8.6 million and the fair value of these guarantees was insignificant.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefit Plans	3 Months Ended
	Dec. 31, 2015
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 months ended December 31, 2015 and 2014 . Components of Net Periodic Benefit Costs (Income) Three Months Ended December 31, 2015 2014 (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 3.5 $ 1.1 $ 3.9 $ 1.7 Interest cost 10.3 3.3 9.8 3.7 Expected return on plan assets (10.2 ) (5.1 ) (11.2 ) (5.2 ) Amortization of prior service cost (credit) 0.1 (4.4 ) 0.1 (3.8 ) Amortization of net actuarial loss 4.2 0.3 4.7 1.1 Net periodic benefit cost (income) 7.9 (4.8 ) 7.3 (2.5 ) Amount allocated to construction projects (1.3 ) 1.0 (1.1 ) 0.5 Amount deferred as regulatory asset/liability — net 1.8 (0.1 ) 1.8 (0.1 ) Amount charged (credited) to expense $ 8.4 $ (3.9 ) $ 8.0 $ (2.1 ) 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)	3 Months Ended
	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income	ACCUMULATED OTHER COMPREHENSIVE INCOME The following tables show the changes in accumulated other comprehensive income (loss) for WGL and Washington Gas by component for the three months ended December 31, 2015 and 2014 . WGL Holdings, Inc. Changes in Accumulated Other Comprehensive Income (Loss) by Component (In thousands) Three Months Ended December 31, 2015 2014 Beginning Balance $ (14,236 ) $ (7,961 ) Qualified cash flow hedging instruments (a) 1,084 (8,265 ) Amortization of net prior service credit (b) (214 ) (171 ) Amortization of net actuarial loss (b) 419 484 Current-period other comprehensive income (loss) 1,289 (7,952 ) Income tax expense (benefit) related to other comprehensive income (loss) 531 (3,947 ) Ending Balance $ (13,478 ) $ (11,966 ) (a) Cash flow hedging instruments represent interest rate swap agreements related to 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 Income (Loss) by Component (In thousands) Three Months Ended December 31, 2015 2014 Beginning Balance $ (6,712 ) $ (6,413 ) Amortization of net prior service credit (a) (214 ) (171 ) Amortization of net actuarial loss (a) 419 484 Current-period other comprehensive income 205 313 Income tax expense related to other comprehensive income 81 124 Ending Balance $ (6,588 ) $ (6,224 ) (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 (Policies)

Accounting Policies (Policies)	3 Months Ended
	Dec. 31, 2015
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), Hampshire Gas Company (Hampshire) and Crab Run Gas Company (Crab Run). 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 . 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. Certain prior period amounts 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 .
Assets Held for Sale	Assets Held for Sale At December 31, 2015 , the Springfield Operations Center met the criteria to be reported as held for sale. Those criteria specify that (a) the asset must be available for immediate sale in its present condition subject only to terms that are usual and customary for sales of such assets and (b) the sale of the asset must be probable, and its transfer expected to qualify for recognition as a completed sale, within one year, with certain exceptions. At December 31, 2015 and September 30, 2015 , the assets and liabilities associated with the Springfield Operations Center are 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.
Storage Gas Valuation Methods	Storage Gas Valuations For Washington Gas and WGL Energy Services, storage gas inventories are stated at the lower-of-cost or market as determined using the first-in, first-out method. For WGL Midstream, storage gas inventory is stated at the lower-of-cost or market using the weighted average cost method. 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 Period	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 2016-01, 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, 2019 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 permits prospective or 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. ASU 2014-09 and ASU 2015-14, Revenue from Contracts with Customers (Topic 606) and Deferral of the Effective Date. The standard 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. The standard permits retrospective application. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.
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	Managing Price Risk. To manage price risk associated with acquiring natural gas supply for utility customers, Washington Gas enters into forward contracts, option contracts, financial contracts and other contracts, as authorized by its regulators. These instruments are accounted for as derivative instruments. 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 newly issued debt. 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. The storage and transportation capacity utilized by WGL Midstream are not considered to be derivative instruments, and thus they are not recorded at fair value on our consolidated balance sheets. Managing Price Risk. WGL Energy Services enters into certain derivative contracts as part of managing 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 minimize 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 derivatives used under this program are subject to mark-to-market accounting treatment while the capacity and transportation resources are not. Regulatory sharing mechanisms allow the profits or losses from these transactions to be shared between Washington Gas' shareholders and customers; therefore, any changes in fair value are recorded through earnings, or as regulatory assets or liabilities to the extent that gains and losses associated with these derivative instruments will be included in the rates charged to customers when they are realized. Valuation changes for the portion of net profits or losses to be retained for shareholders may cause significant period-to-period volatility in earnings from unrealized gains and losses. 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. 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 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. 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.
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; therefore, their carrying amount approximates fair value based on Level 2 inputs. The maturity of our commercial paper outstanding at both December 31, 2015 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. 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 three months ended December 31, 2014 , 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. 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	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. 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. Our agreements with SunEdison and Nextility are accounted for as direct financing leases. WGSW records associated interest in the financing leases in “Other income (expenses)-net” line in the accompanying Consolidated Statements of Income. 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 to the entity, otherwise 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) and Mountain Valley Pipeline, LLC (Mountain Valley) 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. 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)	3 Months Ended
	Dec. 31, 2015
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 months ended December 31, 2015 and 2014 . Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income Three Months Ended December 31, (In millions) 2015 2014 WGL (a) Operating revenues - non-utility $ (1.9 ) $ (17.5 ) Washington Gas Utility cost of gas — (0.7 ) Total Consolidated $ (1.9 ) $ (18.2 ) (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 Date of adoption Effect on the financial statements or other significant matters 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, 2019 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 permits prospective or retrospective application. An entity can defer and present debt issuance costs related to to line-of-credit arrangements as an asset and subsequently amortizing 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. ASU 2014-09 and ASU 2015-14, Revenue from Contracts with Customers (Topic 606) and Deferral of the Effective Date. The standard 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. The standard permits retrospective application. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.

Accounts Payable and Other Ac23

Accounts Payable and Other Accrued Liabilities (Tables)	3 Months Ended
	Dec. 31, 2015
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) December 31, 2015 September 30, 2015 Accounts payable—trade $ 261.6 $ 277.3 Employee benefits and payroll accruals 19.2 31.4 Other accrued liabilities 28.5 16.4 Total $ 309.3 $ 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) December 31, 2015 September 30, 2015 Accounts payable—trade $ 108.8 $ 122.2 Employee benefits and payroll accruals 18.2 29.5 Other accrued liabilities 11.2 7.6 Total $ 138.2 $ 159.3

Short-Term Debt (Tables)

Short-Term Debt (Tables)	3 Months Ended
	Dec. 31, 2015
Short-term Debt [Abstract]
Committed Credit Available	The following is a summary of committed credit available at December 31, 2015 and September 30, 2015 . Committed Credit Available (In millions) December 31, 2015 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 (320.4 ) (207.5 ) (527.9 ) Net committed credit available $ 129.6 $ 142.5 $ 272.1 Weighted average interest rate 0.55 % — 0.42 % 0.50 % 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)	3 Months Ended
	Dec. 31, 2015
Long-term Debt, by Current and Noncurrent [Abstract]
Long-Term Debt Outstanding	The following tables show the outstanding notes as of December 31, 2015 and September 30, 2015 . Long-Term Debt Outstanding ($ In millions) WGL (a) Washington Gas Total Consolidated December 31, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 Weighted average interest rate 3.66 % 5.58 % 5.08 % September 30, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 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 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 for the three months ended December 31, 2014 . There were no retirements for WGL or Washington Gas for the three months ended December 31, 2014 . Long-Term Debt Issuances ($ In millions) Principal (b) Interest Rate Effective Cost (c) Nominal Maturity Date Three Months Ended December 31, 2014 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 for WGL and both MTNs and private placement notes for Washington Gas. (c) The estimated effective cost of the issued notes, including consideration of issuance fees and hedge costs.

Common Shareholders' Equity (Ta

Common Shareholders' Equity (Tables)	3 Months Ended
	Dec. 31, 2015
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 three months ended December 31, 2015 . WGL Holdings, Inc. Components of Common Shareholders’ Equity (In thousands) Common Stock Amount Paid-In Capital Retained Earnings Accumulated Other Comprehensive Income (Loss), Net of Taxes Total Balance at September 30, 2015 $ 485,456 $ 14,934 $ 757,093 $ (14,236 ) $ 1,243,247 Net income — — 68,501 — 68,501 Other comprehensive income — — — 758 758 Stock-based compensation (a) 5,947 (6,016 ) (40 ) — (109 ) Issuance of common stock 83 — — — 83 Dividends declared: Common stock — — (23,048 ) — (23,048 ) Preferred stock — — (330 ) — (330 ) Balance at December 31, 2015 $ 491,486 $ 8,918 $ 802,176 $ (13,478 ) $ 1,289,102 (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) Common Stock Amount Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss, Net of Taxes Total Balance at September 30, 2015 $ 46,479 $ 483,677 $ 557,848 $ (6,712 ) $ 1,081,292 Net income — — 54,612 — 54,612 Other comprehensive loss — — — 124 124 Stock-based compensation — (117 ) — — (117 ) Dividends declared: Common stock — — (19,933 ) — (19,933 ) Preferred stock — — (330 ) — (330 ) Balance at December 31, 2015 $ 46,479 $ 483,560 $ 592,197 $ (6,588 ) $ 1,115,648

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings per Share	The following table reflects the computation of our basic and diluted EPS for the three months ended December 31, 2015 and 2014 . Basic and Diluted EPS (in thousands, except per share data) Net Income Applicable to Common Stock Shares Per Share Amount Three Months Ended December 31, 2015 Basic EPS $ 68,171 49,807 $ 1.37 Stock-based compensation plans — 223 Diluted EPS $ 68,171 50,030 $ 1.36 Three Months Ended December 31, 2014 Basic EPS $ 63,888 49,946 $ 1.28 Stock-based compensation plans — 145 Diluted EPS $ 63,888 50,091 $ 1.28

Derivative and Weather Relate28

Derivative and Weather Related Instruments (Tables)	3 Months Ended
	Dec. 31, 2015
Derivative [Line Items]
Absolute Notional Amounts of Open Positions on Derivative Instruments	At December 31, 2015 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 December 31, 2015 Notional Amounts Natural Gas (In millions of therms) Asset Optimization 21,553.3 13,148.3 Retail sales 57.0 — Other risk-management activities 1,909.4 1,372.1 Electricity (In millions of kWhs) Retail sales 4,758.2 — Other risk-management activities 21,578.8 — Interest Rate Swaps (In millions of dollars) $ 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 19,965.7 — Interest Rate Swaps (In millions of dollars) $ 125.0 $ —
Balance Sheet Classification of Derivative Instruments	The following tables present the balance sheet classification for all derivative instruments as of December 31, 2015 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 December 31, 2015 Gross Derivative Assets Gross Derivative Liabilities Gross Derivative Assets Gross Derivative Liabilities Netting of Collateral Total (a) Current Assets—Derivatives $ 22.9 $ (0.9 ) $ — $ — $ — $ 22.0 Deferred Charges and Other Assets—Derivatives 29.9 (0.2 ) — — — 29.7 Current Liabilities—Derivatives 18.3 (100.7 ) — — 15.3 (67.1 ) Deferred Credits—Derivatives 7.6 (276.2 ) — (2.3 ) 9.1 (261.8 ) Total $ 78.7 $ (378.0 ) $ — $ (2.3 ) $ 24.4 $ (277.2 ) 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 months ended December 31, 2015 and 2014 . Gains and Losses on Derivative Instruments (In millions) WGL Holdings, Inc. Washington Gas Three Months Ended December 31, 2015 2014 2015 2014 Recorded to income Operating revenues—non-utility $ 25.7 $ 75.4 $ — $ — Utility cost of gas 21.4 25.8 21.4 25.8 Non-utility cost of energy-related sales 7.5 (49.6 ) — — Interest expense — (0.4 ) — — Recorded to regulatory assets Gas costs 34.8 28.2 34.8 28.2 Recorded to other comprehensive income (a) 1.1 (8.2 ) — — Total $ 90.5 $ 71.2 $ 56.2 $ 54.0 (a) Represents the effective portion of our cash flow hedges.
Potential Collateral Requirements for Derivative Liabilities with Credit-risk-Contingent Features	December 31, 2015 and September 30, 2015 , respectively. Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features (In millions) WGL Holdings, Inc. Washington Gas December 31, 2015 Derivative liabilities with credit-risk-contingent features $ 63.5 $ 17.1 Maximum potential collateral requirements 53.6 15.0 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 December 31, 2015 Gross Gross Netting of Total (a) Current Assets—Derivatives $ 6.5 $ (0.4 ) $ — $ 6.1 Deferred Charges and Other Assets—Derivatives 14.5 (0.2 ) — 14.3 Current Liabilities—Derivatives 5.0 (30.9 ) 1.9 (24.0 ) Deferred Credits—Derivatives — (228.5 ) — (228.5 ) Total $ 26.0 $ (260.0 ) $ 1.9 $ (232.1 ) 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 December 31, 2015 or September 30, 2015 .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2015
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 December 31, 2015 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 December 31, 2015 Assets Natural gas related derivatives $ — $ 25.3 $ 35.7 $ 61.0 Electricity related derivatives — 2.2 15.5 17.7 Total Assets $ — $ 27.5 $ 51.2 $ 78.7 Liabilities Natural gas related derivatives $ — $ (56.1 ) $ (279.3 ) $ (335.4 ) Electricity related derivatives — (2.7 ) (39.9 ) (42.6 ) Interest rate derivatives — (2.3 ) — (2.3 ) Total Liabilities $ — $ (61.1 ) $ (319.2 ) $ (380.3 ) 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 December 31, 2015 and September 30, 2015 . Quantitative Information about Level 3 Fair Value Measurements (In millions) Net Fair Value Valuation Techniques Unobservable Inputs Range WGL Holdings, Inc. Natural gas related derivatives $(243.6) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.147) - $3.148 Option Model Natural Gas Basis Price (per dekatherm) ($0.183) - $3.208 Annualized Volatility of Spot Market Natural Gas 25.0% - 755.3% Electricity related derivatives $(24.4) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($6.32) - $71.75 Washington Gas Light Company Natural gas related derivatives $(222.1) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($1.147) - $2.250 Net Fair Value 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 months ended December 31, 2015 and 2014 , 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 December 31, 2015 Balance at October 1, 2015 $ (309.7 ) $ (16.0 ) $ (325.7 ) Realized and unrealized gains (losses) Recorded to income 22.8 (22.3 ) 0.5 Recorded to regulatory assets—gas costs 29.6 — 29.6 Transfers into Level 3 (0.9 ) — (0.9 ) Transfers out of Level 3 8.9 — 8.9 Purchases — 6.4 6.4 Settlements 5.7 7.5 13.2 Balance at December 31, 2015 $ (243.6 ) $ (24.4 ) $ (268.0 ) Three Months Ended December 31, 2014 Balance at October 1, 2014 $ (294.7 ) $ (5.0 ) $ (299.7 ) Realized and unrealized gains (losses) Recorded to income 20.3 (10.9 ) 9.4 Recorded to regulatory assets—gas costs 13.6 — 13.6 Transfers out of Level 3 (1.7 ) — (1.7 ) Purchases — 3.2 3.2 Settlements 9.9 1.2 11.1 Balance at December 31, 2014 $ (252.6 ) $ (11.5 ) $ (264.1 )
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 months ended December 31, 2015 and 2014 , 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 December 31, 2015 Operating revenues—non-utility $ 9.5 $ (12.2 ) $ (2.7 ) Utility cost of gas 17.0 — 17.0 Non-utility cost of energy-related sales (3.7 ) (10.1 ) (13.8 ) Total $ 22.8 $ (22.3 ) $ 0.5 Three Months Ended December 31, 2014 Operating revenues—non-utility $ 10.5 $ 20.8 $ 31.3 Utility cost of gas 14.7 — 14.7 Non-utility cost of energy-related sales (4.9 ) (31.7 ) (36.6 ) Total $ 20.3 $ (10.9 ) $ 9.4
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 months ended December 31, 2015 and 2014 , 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 December 31, 2015 Recorded to income Operating revenues—non-utility $ 11.3 $ (5.0 ) $ 6.3 Utility cost of gas 15.9 — 15.9 Non-utility cost of energy-related sales (4.4 ) (3.6 ) (8.0 ) Recorded to regulatory assets—gas costs 27.0 — 27.0 Total $ 49.8 $ (8.6 ) $ 41.2 Three Months Ended December 31, 2014 Recorded to income Operating revenues—non-utility $ 11.9 $ 20.8 $ 32.7 Utility cost of gas 14.8 — 14.8 Non-utility cost of energy-related sales (5.5 ) (27.1 ) (32.6 ) Recorded to regulatory assets—gas costs 18.5 — 18.5 Total $ 39.7 $ (6.3 ) $ 33.4
Fair Value of Financial Instruments	The following table presents the carrying amounts and estimated fair values of our financial instruments at December 31, 2015 and September 30, 2015 . WGL Holdings, Inc. Fair Value of Financial Instruments December 31, 2015 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 21.4 $ 21.4 $ 11.0 $ 11.0 Other short-term investments (a) $ 0.5 $ 0.5 $ 0.4 $ 0.4 Commercial paper (b) $ 527.9 $ 527.9 $ 332.0 $ 332.0 Long-term debt (c) $ 945.6 $ 1,028.5 $ 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 December 31, 2015 Assets Natural gas related derivatives $ — $ 12.8 $ 13.2 $ 26.0 Total Assets $ — $ 12.8 $ 13.2 $ 26.0 Liabilities Natural gas related derivatives $ — $ (24.7 ) $ (235.3 ) $ (260.0 ) Total Liabilities $ — $ (24.7 ) $ (235.3 ) $ (260.0 ) 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 December 31, 2015 Balance at October 1, 2015 $ (281.1 ) Realized and unrealized gains (losses) Recorded to income 17.0 Recorded to regulatory assets—gas costs 29.6 Transfers into Level 3 (0.2 ) Transfers out of Level 3 8.8 Settlements 3.8 Balance at December 31, 2015 $ (222.1 ) Three Months Ended December 31, 2014 Balance at October 1, 2014 $ (270.6 ) Realized and unrealized gains (losses) Recorded to income 14.7 Recorded to regulatory assets—gas costs 13.6 Transfers out of Level 3 (1.7 ) Settlements 9.2 Balance at December 31, 2014 $ (234.8 )
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 December 31, 2015 Utility cost of gas $ 17.0 Total $ 17.0 Three Months Ended December 31, 2014 Utility cost of gas $ 14.7 Total $ 14.7
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 December 31, 2015 Recorded to income - utility cost of gas $ 15.9 Recorded to regulatory assets—gas costs 27.0 Total $ 42.9 Three Months Ended December 31, 2014 Recorded to income - utility cost of gas $ 14.8 Recorded to regulatory assets—gas costs 18.5 Total $ 33.3
Fair Value of Financial Instruments	Washington Gas Light Company Fair Value of Financial Instruments December 31, 2015 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 5.7 $ 5.7 $ 4.3 $ 4.3 Other short-term investments (a) $ 0.5 $ 0.5 $ 0.4 $ 0.4 Commercial paper (b) $ 207.5 $ 207.5 $ 89.0 $ 89.0 Long-term debt (c) $ 697.2 $ 789.3 $ 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) Less current maturities and unamortized discounts.

Operating Segment Reporting (Ta

Operating Segment Reporting (Tables)	3 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Operating Segment Financial Information	The following tables present operating segment information for the three months ended December 31, 2015 and 2014 . 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 December 31, 2015 Regulated utility $ 295,246 $ 27,595 $ — $ 99,289 $ 4,400,622 $ 83,561 $ — Retail energy-marketing 289,395 306 — (567 ) 482,780 430 — Commercial energy systems 15,622 3,481 394 943 729,312 17,022 62,618 Midstream energy services 21,210 35 869 20,839 258,013 — 82,565 Other activities — — — (780 ) 273,819 — — Eliminations (b) (8,089 ) (5 ) — 27 (644,291 ) — — Total consolidated $ 613,384 $ 31,412 $ 1,263 $ 119,751 $ 5,500,255 $ 101,013 $ 145,183 Three Months Ended December 31, 2014 Regulated utility $ 387,193 $ 26,952 $ — $ 114,627 $ 4,200,780 $ 89,603 $ — Retail energy-marketing 330,489 167 — (15,895 ) 436,204 34 — Commercial energy systems 9,539 2,235 577 259 544,682 43,317 66,100 Midstream energy services 28,092 31 536 26,771 249,789 — 36,167 Other activities — — 31 (7,099 ) 409,123 — 48 Eliminations (b) (6,076 ) (25 ) — (32 ) (692,486 ) — — Total consolidated $ 749,237 $ 29,360 $ 1,144 $ 118,631 $ 5,148,092 $ 132,954 $ 102,315 (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, 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 December 31, (In thousands) 2015 2014 Total consolidated EBIT $ 119,751 $ 118,631 Interest expense 12,760 12,310 Income before income taxes 106,991 106,321 Income tax expense 38,490 42,103 Net income 68,501 64,218 Dividends on Washington Gas Light Company preferred stock 330 330 Net income applicable to common stock $ 68,171 $ 63,888

Other Investment (Tables)

Other Investment (Tables)	3 Months Ended
	Dec. 31, 2015
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 $ 2.2 2017 2.2 2018 2.2 2019 2.1 2020 2.2 Thereafter 30.7 Total $ 41.6
Location of Investments	The income statement location of the investments discussed in this footnote for the three months ended December 31, 2015 and 2014 are as follows: WGL Holdings, Inc. Income Statement Location of Other Investments (In millions) VIEs Non-VIEs Total Three Months Ended December 31, 2015 Equity in earnings of unconsolidated affiliates $ 0.4 $ 0.9 $ 1.3 Depreciation and amortization 0.1 — 0.1 Other income—net 0.9 — 0.9 Net income $ 1.2 $ 0.9 $ 2.1 Three Months Ended December 31, 2014 Equity in earnings of unconsolidated affiliates $ 0.6 $ 0.5 $ 1.1 Depreciation and amortization 0.1 — 0.1 Other income (expenses)—net 0.6 (5.6 ) (5.0 ) Net income (loss) $ 1.1 $ (5.1 ) $ (4.0 ) The balance sheet location of the investments discussed in this footnote at December 31, 2015 and September 30, 2015 are as follows: WGL Holdings, Inc. Balance Sheet Location of Other Investments As of December 31, 2015 (in millions) VIEs Non-VIEs Total Assets Investments in unconsolidated affiliates $ 98.9 $ 46.3 $ 145.2 Investments in direct financing leases, capital leases 34.8 — 34.8 Accounts receivable 1.7 4.2 (a) 5.9 Total assets $ 135.4 $ 50.5 $ 185.9 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.

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	The following table presents the receivables and payables from associated companies as of December 31, 2015 and September 30, 2015 . Washington Gas Receivables / Payables from Associated Companies (In millions) December 31, 2015 September 30, 2015 Receivables from Associated Companies $ 4.5 $ 3.2 Payables to Associated Companies $ 82.3 $ 68.6 The following table shows the amounts Washington Gas charged WGL Energy Services for balance services. Washington Gas - Gas Balancing Service Charges Three Months Ended December 31, (In millions) 2015 2014 Gas balancing service charge $ 7.1 $ 5.5

Pension and Other Post-Retire33

Pension and Other Post-Retirement Benefit Plan (Tables)	3 Months Ended
	Dec. 31, 2015
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 months ended December 31, 2015 and 2014 . Components of Net Periodic Benefit Costs (Income) Three Months Ended December 31, 2015 2014 (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Service cost $ 3.5 $ 1.1 $ 3.9 $ 1.7 Interest cost 10.3 3.3 9.8 3.7 Expected return on plan assets (10.2 ) (5.1 ) (11.2 ) (5.2 ) Amortization of prior service cost (credit) 0.1 (4.4 ) 0.1 (3.8 ) Amortization of net actuarial loss 4.2 0.3 4.7 1.1 Net periodic benefit cost (income) 7.9 (4.8 ) 7.3 (2.5 ) Amount allocated to construction projects (1.3 ) 1.0 (1.1 ) 0.5 Amount deferred as regulatory asset/liability — net 1.8 (0.1 ) 1.8 (0.1 ) Amount charged (credited) to expense $ 8.4 $ (3.9 ) $ 8.0 $ (2.1 )

Accumulated Other Comprehensi34

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Dec. 31, 2015
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 months ended December 31, 2015 and 2014 . WGL Holdings, Inc. Changes in Accumulated Other Comprehensive Income (Loss) by Component (In thousands) Three Months Ended December 31, 2015 2014 Beginning Balance $ (14,236 ) $ (7,961 ) Qualified cash flow hedging instruments (a) 1,084 (8,265 ) Amortization of net prior service credit (b) (214 ) (171 ) Amortization of net actuarial loss (b) 419 484 Current-period other comprehensive income (loss) 1,289 (7,952 ) Income tax expense (benefit) related to other comprehensive income (loss) 531 (3,947 ) Ending Balance $ (13,478 ) $ (11,966 ) (a) Cash flow hedging instruments represent interest rate swap agreements related to 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 Income (Loss) by Component (In thousands) Three Months Ended December 31, 2015 2014 Beginning Balance $ (6,712 ) $ (6,413 ) Amortization of net prior service credit (a) (214 ) (171 ) Amortization of net actuarial loss (a) 419 484 Current-period other comprehensive income 205 313 Income tax expense related to other comprehensive income 81 124 Ending Balance $ (6,588 ) $ (6,224 ) (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 (Details)

Accounting Policies (Details) $ in Millions		3 Months Ended
		Dec. 31, 2015USD ($)subsidiary	Dec. 31, 2014USD ($)
Inventory [Line Items]
Lower of cost or market adjustment		$ (1.9)	$ (18.2)
Washington Gas Resources
Inventory [Line Items]
Number of subsidiaries | subsidiary		4
WGL | Operating revenues - non-utility
Inventory [Line Items]
Lower of cost or market adjustment	[1]	$ (1.9)	(17.5)
Washington Gas Light Company | Utility cost of gas
Inventory [Line Items]
Lower of cost or market adjustment		$ 0	$ (0.7)
[1]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Accounts Payable and Other Ac36

Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Accounts Payable and Other Accrued Liabilities [Line Items]
Accounts payable—trade	$ 261,600	$ 277,300
Employee benefits and payroll accruals	19,200	31,400
Other accrued liabilities	28,500	16,400
Total	309,339	325,146
Washington Gas Light Company
Accounts Payable and Other Accrued Liabilities [Line Items]
Accounts payable—trade	108,800	122,200
Employee benefits and payroll accruals	18,200	29,500
Other accrued liabilities	11,200	7,600
Total	$ 138,218	$ 159,280

Short-Term Debt (Details)

Short-Term Debt (Details) - USD ($)		Dec. 31, 2015	Sep. 30, 2015
Short-term Debt [Line Items]
Less: Commercial Paper		$ (527,875,000)	$ (332,000,000)
Committed Credit
Short-term Debt [Line Items]
Unsecured revolving credit facility	[1]	800,000,000	800,000,000
Less: Commercial Paper		(527,900,000)	(332,000,000)
Net committed credit available		$ 272,100,000	$ 468,000,000
Weighted average interest rate		0.50%	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	[1],[2]	450,000,000	450,000,000
Less: Commercial Paper	[2]	(320,400,000)	(243,000,000)
Net committed credit available	[2]	$ 129,600,000	$ 207,000,000
Weighted average interest rate	[2]	0.55%	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		(207,475,000)	$ (89,000,000)
Outstanding bank loans		0	0
Washington Gas Light Company | Committed Credit
Short-term Debt [Line Items]
Unsecured revolving credit facility	[1]	350,000,000	350,000,000
Less: Commercial Paper		(207,500,000)	(89,000,000)
Net committed credit available		$ 142,500,000	$ 261,000,000
Weighted average interest rate		0.42%	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 ($)		3 Months Ended
		Dec. 31, 2014		Dec. 31, 2015		Sep. 30, 2015
Total Consolidated Issuances
Debt Instrument [Line Items]
Long-term notes		$ 300,000,000	[1]	$ 971,000,000	[2]	$ 971,000,000	[2]
Interest rate				5.08%		5.08%
WGL | Total Consolidated Issuances
Debt Instrument [Line Items]
Long-term notes	[2],[3]			$ 250,000,000		$ 250,000,000
Interest rate	[3]			3.66%		3.66%
Washington Gas Light Company | Issuances
Debt Instrument [Line Items]
Long-term notes		$ 50,000,000	[1]	$ 0
Washington Gas Light Company | Issuances | 12/15/2044
Debt Instrument [Line Items]
Interest rate		4.24%
Principal	[1]	$ 50,000,000
Effective cost	[4]	4.41%
Nominal Maturity Date		Dec. 15, 2044
Washington Gas Light Company | Retirements [Member]
Debt Instrument [Line Items]
Long-term notes		$ 0		0
Washington Gas Light Company | Total Consolidated Issuances
Debt Instrument [Line Items]
Long-term notes	[2]			$ 721,000,000		$ 721,000,000
Interest rate				5.58%		5.58%
Washington Gas Light Company | Medium-Term Notes
Debt Instrument [Line Items]
Unused borrowing capacity amount				$ 600,000,000		$ 600,000,000
WGL Holdings and Subsidiaries Excluding Washington Gas Light Company Member [Member] | Issuances
Debt Instrument [Line Items]
Long-term notes		$ 250,000,000	[1],[5]	0
WGL Holdings and Subsidiaries Excluding Washington Gas Light Company Member [Member] | Issuances | 11/1/2019
Debt Instrument [Line Items]
Interest rate	[5]	2.25%
Principal	[1],[5]	$ 100,000,000
Effective cost	[4],[5]	2.42%
Nominal Maturity Date	[5]	Nov. 1, 2019
WGL Holdings and Subsidiaries Excluding Washington Gas Light Company Member [Member] | Issuances | 11/1/2044
Debt Instrument [Line Items]
Interest rate	[5]	4.60%
Principal	[1],[5]	$ 125,000,000
Effective cost	[4],[5]	5.11%
Nominal Maturity Date	[5]	Nov. 1, 2044
WGL Holdings and Subsidiaries Excluding Washington Gas Light Company Member [Member] | Issuances | 11/01/2044
Debt Instrument [Line Items]
Interest rate	[5]	4.60%
Principal	[1],[5]	$ 25,000,000
Effective cost	[4],[5]	5.53%
Nominal Maturity Date	[5]	Nov. 1, 2044
WGL Holdings and Subsidiaries Excluding Washington Gas Light Company Member [Member] | Retirements [Member]
Debt Instrument [Line Items]
Long-term notes		$ 0		$ 0
[1]	Represents face amount of senior notes for WGL and both MTNs and private placement notes for Washington Gas.
[2]	Includes Senior Notes for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities.
[3]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.
[4]	The estimated effective cost of the issued notes, including consideration of issuance fees and hedge costs.
[5]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Common Shareholders' Equity (De

Common Shareholders' Equity (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		$ 1,243,247
Net income		68,501	$ 64,218
Other comprehensive income (loss)		758	(4,005)
Stock-based compensation(a)	[1]	(109)
Issuance of common stock		83
Common shareholders' equity, ending balance		1,289,102
Dividends declared:
Common stock		(23,048)
Preferred stock		$ (330)
Shares outstanding (in shares)		49,833,349		49,728,662
Common Stock
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		$ 485,456
Stock-based compensation(a)	[1]	5,947
Issuance of common stock		83
Common shareholders' equity, ending balance		491,486
Paid-In Capital
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		14,934
Stock-based compensation(a)	[1]	(6,016)
Common shareholders' equity, ending balance		8,918
Retained Earnings
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		757,093
Net income		68,501
Stock-based compensation(a)	[1]	(40)
Common shareholders' equity, ending balance		802,176
Dividends declared:
Common stock		(23,048)
Preferred stock		(330)
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)		758
Common shareholders' equity, ending balance		(13,478)
Washington Gas Light Company
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		1,081,292
Net income		54,612	64,951
Other comprehensive income (loss)		124	$ 189
Stock-based compensation(a)		(117)
Common shareholders' equity, ending balance		1,115,648
Dividends declared:
Common stock		(19,933)
Preferred stock		$ (330)
Shares outstanding (in shares)		46,479,536		46,479,536
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
Washington Gas Light Company | Paid-In Capital
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		483,677
Stock-based compensation(a)		(117)
Common shareholders' equity, ending balance		483,560
Washington Gas Light Company | Retained Earnings
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Common shareholders' equity, beginning balance		557,848
Net income		54,612
Common shareholders' equity, ending balance		592,197
Dividends declared:
Common stock		(19,933)
Preferred stock		(330)
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)		124
Common shareholders' equity, ending balance		$ (6,588)
[1]	(a) Includes dividend equivalents related to our performance shares.

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income (Loss) applicable to common stock	$ 68,171	$ 63,888
Basic EPS (in shares)	49,807,000	49,946,000
Stock-based compensation plans (in shares)	223,000	145,000
Diluted EPS (in shares)	50,030,000	50,091,000
Basic EPS (in dollars per share)	$ 1.37	$ 1.28
Diluted EPS (in dollars per share)	$ 1.36	$ 1.28
Antidilutive securities excluded from computation of earnings per share	76,000	0

Income Taxes-Balance Sheet (Det

Income Taxes-Balance Sheet (Details) - USD ($)	Dec. 31, 2015	Sep. 30, 2015
Income Tax Expense Benefit Details [Line Items]
Unrecognized tax benefits	$ 35,600,000	$ 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 Relate42

Derivative and Weather Related Instruments (Narrative) (Details) $ in Millions	3 Months Ended
	Dec. 31, 2015USD ($)Counterpartiesderivative	Dec. 31, 2014USD ($)	Sep. 30, 2015USD ($)
Interest Rate Swap
Asset Optimization [Abstract]
Number of interest rate derivatives held | derivative	2
Derivative notional amount			$ 125
Washington Gas Light Company
Asset Optimization [Abstract]
Gain (loss) on asset optimization transactions, net pretax	$ 26.8	$ 31.1
Unrealized gain (loss) on asset optimization derivative instruments, net pretax	19.4	25
Derivative, Collateral [Abstract]
Right to reclaim cash	8.6		3.5
Obligation to return cash	0.4		3.8
Collateral already posted, aggregate fair value	$ 0		0
Concentration of Credit Risk
Number of counterparties | Counterparties	2
Percentage of credit exposure	10.00%
Obligation to counterparties	$ 19.1
WGL Energy Services
Derivative, Collateral [Abstract]
Right to reclaim cash	24.1		12.4
Collateral already posted, aggregate fair value	$ 16.9		10.3
Concentration of Credit Risk
Number of counterparties | Counterparties	3
Percentage of credit exposure	10.00%
Obligation to counterparties	$ 1
Gain (losses) on weather related instruments, pretax	6	$ (1.7)
WGL Midstream
Derivative, Collateral [Abstract]
Right to reclaim cash	8.9		3.5
Obligation to return cash	0.7		0.4
Collateral already posted, aggregate fair value	$ 0		$ 0
Concentration of Credit Risk
Number of counterparties | Counterparties	1
Percentage of credit exposure	10.00%
Obligation to counterparties	$ 13.5

Derivative and Weather Relate43

Derivative and Weather Related Instruments (Details) kWh in Millions, MMBTU in Millions, $ in Millions		Dec. 31, 2015USD ($)kWhMMBTU	Sep. 30, 2015USD ($)kWhMMBTU
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		$ 24.4	$ 10.2
Total	[1]	(277.2)	(330.8)
Derivative Instruments Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Liabilities		(2.3)	(3.4)
Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		78.7	74.5
Gross Derivative Liabilities		(378)	(412.1)
Current Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Total	[1]	22	22.9
Current Assets-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		22.9	29.7
Gross Derivative Liabilities		(0.9)	(6.8)
Deferred Charges and Other Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Total	[1]	29.7	32.1
Deferred Charges and Other Assets-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		29.9	32.3
Gross Derivative Liabilities		(0.2)	(0.2)
Current Liabilities-Derivatives
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		15.3	2.9
Total	[1]	(67.1)	(63.5)
Current Liabilities-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		18.3	9.8
Gross Derivative Liabilities		(100.7)	(76.2)
Deferred Credits-Derivatives
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		9.1	7.3
Total	[1]	(261.8)	(322.3)
Deferred Credits-Derivatives | Derivative Instruments Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Liabilities		(2.3)	(3.4)
Deferred Credits-Derivatives | Derivative Instruments Not Designated as Hedging Instruments
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		7.6	2.7
Gross Derivative Liabilities		$ (276.2)	$ (328.9)
Asset Optimization
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		2,155,330,000	2,082,920,000
Retail sales
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		5,700,000	5,220,000
Electricity notional amounts (in kWhs) | kWh		4,758.2	4,292.7
Other risk-management activities
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		190,940,000	181,170,000
Electricity notional amounts (in kWhs) | kWh		21,578.8	19,965.7
Interest Rate Swap
Absolute Notional Amounts of Open Positions on Derivative Instruments
Derivative notional amount		$ 125	$ 125
Washington Gas Light Company
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	26	20.4
Gross Derivative Liabilities	[2]	(260)	(306.2)
Netting of Collateral	[2]	1.9	0
Total	[1],[2]	(232.1)	(285.8)
Washington Gas Light Company | Current Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	6.5	5.2
Gross Derivative Liabilities	[2]	(0.4)	(0.6)
Total	[1],[2]	6.1	4.6
Washington Gas Light Company | Deferred Charges and Other Assets-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	14.5	13.3
Gross Derivative Liabilities	[2]	(0.2)	(0.1)
Total	[1],[2]	14.3	13.2
Washington Gas Light Company | Current Liabilities-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[2]	5	1.9
Gross Derivative Liabilities	[2]	(30.9)	(35.8)
Netting of Collateral	[2]	1.9	0
Total	[1],[2]	(24)	(33.9)
Washington Gas Light Company | Deferred Credits-Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Liabilities	[2]	(228.5)	(269.7)
Total	[1],[2]	$ (228.5)	$ (269.7)
Washington Gas Light Company | Asset Optimization
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		1,314,830,000	1,331,670,000
Washington Gas Light Company | Retail sales
Absolute Notional Amounts of Open Positions on Derivative Instruments
Electricity notional amounts (in kWhs) | kWh		0	0
Washington Gas Light Company | Other risk-management activities
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural gas notional amounts (in mmbtu) | MMBTU		137,210,000	138,180,000
Electricity notional amounts (in kWhs) | kWh		0	0
Washington Gas Light Company | Interest Rate Swap
Absolute Notional Amounts of Open Positions on Derivative Instruments
Derivative notional amount		$ 0	$ 0
[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 December 31, 2015 or September 30, 2015.

Derivative and Weather Relate44

Derivative and Weather Related Instruments (Gains and Losses) (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Gains and (Losses) on Derivative Instruments
Recorded to other comprehensive income		$ 1,084	[1]	$ (8,265)
Total Gains (losses) on derivative instruments		90,500		71,200
Operating revenues—non-utility
Gains and (Losses) on Derivative Instruments
Recorded to income		25,700		75,400
Utility cost of gas
Gains and (Losses) on Derivative Instruments
Recorded to income		21,400		25,800
Non-utility cost of energy-related sales
Gains and (Losses) on Derivative Instruments
Recorded to income		7,500		(49,600)
Gas costs
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		34,800		28,200
Parent Company | Interest expense
Gains and (Losses) on Derivative Instruments
Recorded to income		0		(400)
Parent Company | Recorded to other comprehensive income
Gains and (Losses) on Derivative Instruments
Total Gains (losses) on derivative instruments	[2]	1,100		(8,200)
Washington Gas Light Company
Gains and (Losses) on Derivative Instruments
Total Gains (losses) on derivative instruments		56,200		54,000
Washington Gas Light Company | Utility cost of gas
Gains and (Losses) on Derivative Instruments
Recorded to income		21,400		25,800
Washington Gas Light Company | Gas costs
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		$ 34,800		$ 28,200
[1]	Cash flow hedging instruments represent interest rate swap agreements related to 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 Relate45

Derivative and Weather Related Instruments (Aggregate Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Potential Collateral Requirements for Derivative Liabilities with Credit-risk-Contingent Features
Derivative liabilities with credit-risk-contingent features	$ 63.5	$ 61.7
Maximum potential collateral requirements	53.6	54.6
Washington Gas Light Company
Potential Collateral Requirements for Derivative Liabilities with Credit-risk-Contingent Features
Derivative liabilities with credit-risk-contingent features	17.1	18.9
Maximum potential collateral requirements	$ 15	$ 18.8

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Hierarchy) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	$ 78.7	$ 74.5
Liabilities	(380.3)	(415.5)
Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	61	51.2
Liabilities	(335.4)	(372.1)
Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	17.7	23.3
Liabilities	(42.6)	(40)
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	(2.3)	(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 Swap
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	27.5	24.7
Liabilities	(61.1)	(40)
Level 2 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	25.3	22.7
Liabilities	(56.1)	(33.9)
Level 2 | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	2.2	2
Liabilities	(2.7)	(2.7)
Level 2 | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Liabilities	(2.3)	(3.4)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	51.2	49.8
Liabilities	(319.2)	(375.5)
Level 3 | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	35.7	28.5
Liabilities	(279.3)	(338.2)
Level 3 | Electricity Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	15.5	21.3
Liabilities	(39.9)	(37.3)
Level 3 | Interest Rate Swap
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	26	20.4
Liabilities	(260)	(306.2)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	26	20.4
Liabilities	(260)	(306.2)
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 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	12.8	6.9
Liabilities	(24.7)	(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	12.8	6.9
Liabilities	(24.7)	(11.6)
Washington Gas Light Company | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	13.2	13.5
Liabilities	(235.3)	(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	13.2	13.5
Liabilities	$ (235.3)	$ (294.6)

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative information) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015USD ($)$ / MwH$ / dekatherm	Sep. 30, 2015USD ($)$ / MwH$ / dekatherm	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (268)	$ (325.7)	$ (264.1)	$ (299.7)
Natural Gas Related Derivatives
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (243.6)	$ (309.7)	(252.6)	(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)	3.148	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)	(1.147)	(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)	3.208	2.950
Natural Gas Related Derivatives | Option Model | Maximum | Annualized Volatility Price
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Option Volatility Percentage	755.30%	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)	(0.183)	(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 | $	$ (24.4)	$ (16)	(11.5)	(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	71.750	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	(6.32)	(5.75)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net Fair Value | $	$ (222.1)	$ (281.1)	$ (234.8)	$ (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)	2.250	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)	(1.147)	(1.441)

Fair Value Measurements (Reconc

Fair Value Measurements (Reconciliation with Level 3 Inputs) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ (325.7)	$ (299.7)
Recorded to income	0.5	9.4
Recorded to regulatory assets—gas costs	29.6	13.6
Transfers into Level 3	(0.9)
Transfers out of Level 3	8.9	(1.7)
Purchases	6.4	3.2
Settlements	13.2	11.1
Ending balance	(268)	(264.1)
Natural Gas Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(309.7)	(294.7)
Recorded to income	22.8	20.3
Recorded to regulatory assets—gas costs	29.6	13.6
Transfers into Level 3	(0.9)
Transfers out of Level 3	8.9	(1.7)
Settlements	5.7	9.9
Ending balance	(243.6)	(252.6)
Electricity Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(16)	(5)
Recorded to income	(22.3)	(10.9)
Purchases	6.4	3.2
Settlements	7.5	1.2
Ending balance	(24.4)	(11.5)
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	(281.1)	(270.6)
Recorded to income	17	14.7
Recorded to regulatory assets—gas costs	29.6	13.6
Transfers into Level 3	(0.2)
Transfers out of Level 3	8.8	(1.7)
Settlements	3.8	9.2
Ending balance	$ (222.1)	$ (234.8)

Fair Value Measurements (Realiz

Fair Value Measurements (Realized and Unrealized Gains and Losses with Level 3 Measurements) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
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	$ 0.5	$ 9.4
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	27	18.5
Total	41.2	33.4
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	22.8	20.3
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	27	18.5
Total	49.8	39.7
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	(22.3)	(10.9)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Total	(8.6)	(6.3)
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	(2.7)	31.3
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	6.3	32.7
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	9.5	10.5
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	11.3	11.9
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	(12.2)	20.8
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(5)	20.8
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	17	14.7
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	15.9	14.8
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	17	14.7
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	15.9	14.8
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	(13.8)	(36.6)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(8)	(32.6)
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	(3.7)	(4.9)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(4.4)	(5.5)
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	(10.1)	(31.7)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(3.6)	(27.1)
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	17	14.7
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	27	18.5
Total	42.9	33.3
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	17	14.7
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	$ 15.9	$ 14.8

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Amounts and Estimated Fair Value) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Sep. 30, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial Paper		$ 527,875	$ 332,000
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	21,400	11,000
Other Short-term Investments	[1]	500	400
Commercial Paper	[2]	527,900	332,000
Long-term debt	[3]	945,600	944,200
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	21,400	11,000
Other Short-term Investments	[1]	500	400
Commercial Paper	[2]	527,900	332,000
Long-term debt	[3]	1,028,500	1,057,900
Washington Gas Light Company
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial Paper		207,475	89,000
Washington Gas Light Company | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	5,700	4,300
Other Short-term Investments	[1]	500	400
Commercial Paper	[2]	207,500	89,000
Long-term debt	[3]	697,200	695,900
Washington Gas Light Company | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds	[1]	5,700	4,300
Other Short-term Investments	[1]	500	400
Commercial Paper	[2]	207,500	89,000
Long-term debt	[3]	$ 789,300	$ 811,900
[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]	Less current maturities and unamortized discounts.

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) $ in Millions	3 Months Ended
	Dec. 31, 2014USD ($)
Washington Gas Resources
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment loss	$ 5.6

Operating Segment (Narrative) (

Operating Segment (Narrative) (Details)	3 Months Ended
	Dec. 31, 2015segment
Segment Reporting [Abstract]
Number of operating segments	4

Operating Segment Financial Inf

Operating Segment Financial Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Operating Segment Financial Information [Line Items]
Operating Revenues	[1]	$ 613,384	$ 749,237
Operating Revenue, Regulated Utility		288,153	381,712
Operating Revenue, Non-Utility		325,231	367,525
Depreciation and Amortization		31,412	29,360
Equity in Earnings of Unconsolidated Affiliates		1,263	1,144
EBIT		119,751	118,631
Total Assets		5,500,255	5,148,092	$ 5,261,359
Capital Expenditures		101,013	132,954
Equity Method Investments		145,183	102,315
Other activities
Operating Segment Financial Information [Line Items]
Equity in Earnings of Unconsolidated Affiliates		0	31
EBIT		(780)	(7,099)
Total Assets		273,819	409,123
Equity Method Investments		0	48
Eliminations
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1],[2]	(8,089)	(6,076)
Depreciation and Amortization	[2]	(5)	(25)
EBIT	[2]	27	(32)
Total Assets	[2]	(644,291)	(692,486)
Regulated utility
Operating Segment Financial Information [Line Items]
Operating Revenue, Regulated Utility	[1]	295,246	387,193
Depreciation and Amortization		27,595	26,952
EBIT		99,289	114,627
Total Assets		4,400,622	4,200,780
Capital Expenditures		83,561	89,603
Retail energy-marketing
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1]	289,395	330,489
Depreciation and Amortization		306	167
EBIT		(567)	(15,895)
Total Assets		482,780	436,204
Capital Expenditures		430	34
Commercial energy systems
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1]	15,622	9,539
Depreciation and Amortization		3,481	2,235
Equity in Earnings of Unconsolidated Affiliates		394	577
EBIT		943	259
Total Assets		729,312	544,682
Capital Expenditures		17,022	43,317
Equity Method Investments		62,618	66,100
Midstream energy services
Operating Segment Financial Information [Line Items]
Operating Revenue, Non-Utility	[1]	21,210	28,092
Depreciation and Amortization		35	31
Equity in Earnings of Unconsolidated Affiliates		869	536
EBIT		20,839	26,771
Total Assets		258,013	249,789
Equity Method Investments		$ 82,565	$ 36,167
[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, 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
	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting [Abstract]
Total consolidated EBIT	$ 119,751	$ 118,631
Interest expense	12,760	12,310
INCOME BEFORE INCOME TAXES	106,991	106,321
Income tax expense	38,490	42,103
NET INCOME	68,501	64,218
Dividends on Washington Gas Light Company preferred stock	330	330
NET INCOME APPLICABLE TO COMMON STOCK	$ 68,171	$ 63,888

Other Investments (Narrative) (

Other Investments (Narrative) (Details) $ in Thousands, MMBTU in Millions	3 Months Ended
	Dec. 31, 2014USD ($)	Dec. 31, 2015USD ($)MMBTUcompanyinvestmentagreementmi	Sep. 30, 2015USD ($)	Mar. 31, 2015	Sep. 30, 2014USD ($)
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		$ 145,183	$ 136,884
Investments in direct financing leases, capital leases		$ 34,751	35,234
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		$ 36,300	30,500
Maximum financial exposure		59,400
ASD Solar, LP
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Maximum financial exposure		$ 72,600
Constitution
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Ownership percentage		10.00%
Investments in unconsolidated affiliates		$ 36,300
Maximum financial exposure		31,800
Estimated investment In constitution		83,000
Washington Gas Resources Corp. | American Solar Direct Holdings Inc. (ASDHI)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost method investments					$ 5,600
Impairment loss	$ 5,600
WGSW
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Residual value		9,700
Tax credits		4,600
Unearned income		19,400
Initial direct costs		700
WGSW | Sun Edison/Nextility
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Investments in direct financing leases, capital leases		36,500	37,200
Current investment recorded in accounts receivable		$ 1,700	2,000
Number of agreements | agreement		2
Number of counterparties | company		2
WGSW | ASD Solar, LP
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Investments in unconsolidated affiliates		$ 62,600	$ 63,500
Difference between carrying amount and underlying equity		$ 35,900
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		$ 9,900
Pro rata share of project cost		4,200
Minimum | Mistream Energy Services [Member] | Constitution
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Ownership percentage			5.00%
Maximum | Mistream Energy Services [Member] | Constitution
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Ownership percentage			50.00%
External Partners | WGL Midstream | Mountain Valley Pipeline
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Minimum financial exposure		$ 97,900
External Partners | WGL Midstream | Mountain Valley Pipeline
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Ownership interest in joint venture after funding requirements are met		3.00%
Scenario, Plan | WGL Midstream | Mountain Valley Pipeline
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Pro rata share of project cost		$ 228,000
Performance guarantee | WGL Midstream | Mountain Valley Pipeline
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Maximum financial exposure		20,000
Performance guarantee | WGL Midstream | WGL Midstream | Mountain Valley Pipeline
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Minimum financial exposure		$ 14,000

Other Investments Financing Lea

Other Investments Financing Leases Table (Details) - WGSW $ in Millions	Dec. 31, 2015USD ($)
Minimum Payments Receivable for Direct Financing Leases
Remainder of 2016	$ 2.2
2,017	2.2
2,018	2.2
2,019	2.1
2,020	2.2
Thereafter	30.7
Total	$ 41.6

Other Investments Balance Sheet

Other Investments Balance Sheet Location Table (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Sep. 30, 2015
Assets [Abstract]
Investments in unconsolidated affiliates		$ 145,183	$ 136,884
Investments in direct financing leases, capital leases		34,751	35,234
VIEs
Assets [Abstract]
Investments in unconsolidated affiliates		98,900	94,000
Investments in direct financing leases, capital leases		34,800	35,200
Accounts receivable		1,700	2,000
Total assets		135,400	131,200
Non VIEs
Assets [Abstract]
Investments in unconsolidated affiliates		46,300	42,900
Accounts receivable	[1]	4,200	4,200
Total assets		50,500	47,100
Total
Assets [Abstract]
Investments in unconsolidated affiliates		145,200	136,900
Investments in direct financing leases, capital leases		34,800	35,200
Accounts receivable		5,900	6,200
Total assets		$ 185,900	$ 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
	Dec. 31, 2015	Dec. 31, 2014
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	$ 1,263	$ 1,144
Other income (expenses)-net	979	(4,355)
NET INCOME	68,501	64,218
VIEs
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	400	600
Depreciation and amortization	100	100
Other income (expenses)-net	900	600
NET INCOME	1,200	1,100
Non VIEs
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	900	500
Depreciation and amortization	0	0
Other income (expenses)-net	0	(5,600)
NET INCOME	900	(5,100)
Total Other Investments
Net Income (Loss) Attributable to Parent [Abstract]
Equity in earnings of unconsolidated affiliates	1,300	1,100
Depreciation and amortization	100	100
Other income (expenses)-net	900	(5,000)
NET INCOME	$ 2,100	$ (4,000)

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Washington Gas Light Company
Related Party Transaction [Line Items]
Receivables from associated companies	$ 4,500		$ 3,200
Payables to associated companies	82,300		68,600
WGL Energy Services | Washington Gas Light Company
Related Party Transaction [Line Items]
Accounts payable, related parties	3,200		500
Washington Gas Light Company
Related Party Transaction [Line Items]
Receivables from associated companies	4,469		3,176
Payables to associated companies	82,267		68,623
Washington Gas Light Company | WGL Energy Services
Related Party Transaction [Line Items]
Gas balancing service charge	7,100	$ 5,500
Receivables purchased from related party	$ 8,600		$ 6,600

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2015	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	$ 30.7
Parent Company | WGL Energy Services | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	259
Parent Company | WGL Midstream | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	333.5
Parent Company | Other External Partners [Member] | Performance guarantee
Commitments And Contingencies [Line Items]
Financial guarantees	8.6
Parent Company | Other Non-Utility [Member] | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	2
Parent Company | WGL Energy Systems | Guarantee on behalf of subsidiary
Commitments And Contingencies [Line Items]
Financial guarantees	$ 8.6

Pension and Other Post-Retire61

Pension and Other Post-Retirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Amortization period regulatory assets liabilities-net	5 years
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3.5	$ 3.9
Interest cost	10.3	9.8
Expected return on plan assets	(10.2)	(11.2)
Amortization of prior service cost (credit)	0.1	0.1
Amortization of net actuarial loss	4.2	4.7
Net periodic benefit cost (income)	7.9	7.3
Amount allocated to construction projects	(1.3)	(1.1)
Amortization of regulatory asset (liability)-net	1.8	1.8
Amount charged (credited) to expense	8.4	8
Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.1	1.7
Interest cost	3.3	3.7
Expected return on plan assets	(5.1)	(5.2)
Amortization of prior service cost (credit)	(4.4)	(3.8)
Amortization of net actuarial loss	0.3	1.1
Net periodic benefit cost (income)	(4.8)	(2.5)
Amount allocated to construction projects	1	0.5
Amortization of regulatory asset (liability)-net	(0.1)	(0.1)
Amount charged (credited) to expense	$ (3.9)	$ (2.1)

Accumulated Other Comprehensi62

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015		Dec. 31, 2014
AOCI, Net of Tax [Roll Forward]
Beginning Balance	$ (14,236)		$ (7,961)
Qualified cash flow hedging instruments	1,084	[1]	(8,265)
Change in net prior service credit	(214)	[2]	(171)
Change in actuarial net loss	419	[2]	484
Current-period other comprehensive income	1,289		(7,952)
Income tax expense (benefit) related to other comprehensive income (loss)	531		(3,947)
Ending Balance	(13,478)		(11,966)
Washington Gas Light Company
AOCI, Net of Tax [Roll Forward]
Beginning Balance	(6,712)		(6,413)
Change in net prior service credit	(214)	[2]	(171)
Change in actuarial net loss	419	[2]	484	[3]
Current-period other comprehensive income	205		313
Income tax expense (benefit) related to other comprehensive income (loss)	81		124
Ending Balance	$ (6,588)		$ (6,224)
[1]	Cash flow hedging instruments represent interest rate swap agreements related to 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.