Washington Gas Light (WGLCP) 10-K 22 Nov 16 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2016	Oct. 31, 2016	Mar. 31, 2016
Document Information [Line Items]
Entity Registrant Name	WGL Holdings Inc.
Entity Central Index Key	1,103,601
Document Type	10-K
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 3,611,520,637
Entity Common Stock, Shares Outstanding		51,187,031
Washington Gas Light Company
Document Information [Line Items]
Entity Registrant Name	Washington Gas Light Company
Entity Central Index Key	104,819
Document Type	10-K
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Sep. 30, 2016		Sep. 30, 2015
Property, Plant and Equipment
At original cost		$ 5,542,916		$ 5,003,910
Accumulated depreciation and amortization		(1,415,679)		(1,331,182)
Net property, plant and equipment		4,127,237	[1]	3,672,728
Current Assets
Cash and cash equivalents		5,573		6,733
Receivables
Accounts receivable		329,989		276,358
Gas costs and other regulatory assets		15,294		5,797
Unbilled revenues		173,076		102,560
Allowance for doubtful accounts		(27,339)		(26,224)
Net receivables		491,020		358,491
Materials and supplies—principally at average cost		18,414		21,402
Storage gas		207,132		211,443
Prepaid taxes		33,397		48,726
Other prepayments		42,626		32,850
Derivatives		18,510		22,933
Assets held for sale		0		22,906
Other		26,802		23,057
Total current assets		843,474		748,541
Deferred Charges and Other Assets
Gas costs		179,856		190,676
Pension and other post-retirement benefits		223,242		212,041
Other		98,592		80,018
Prepaid post-retirement benefits		180,686		138,629
Derivatives		55,020		32,132
Investments in direct financing leases, capital leases		29,780		35,234
Investments in unconsolidated affiliates		303,491		136,884
Other		17,327		14,476
Total deferred charges and other assets		1,087,994		840,090
Total Assets		6,058,705		5,261,359
Capitalization
WGL Holdings common shareholders’ equity		1,375,561		1,243,247
Non-controlling Interest		409		0
Washington Gas Light Company preferred stock		28,173		28,173
Total Equity		1,404,143		1,271,420
Long-term debt		1,444,300		944,201
Total capitalization		2,848,443		2,215,621
Current Liabilities
Current maturities of long-term debt		0		25,000
Notes payable		331,385		332,000
Accounts payable and other accrued liabilities		405,351		325,146
Wages payable		17,908		21,091
Accrued interest		7,645		7,835
Dividends declared		25,283		23,377
Customer deposits and advance payments		86,384		88,897
Gas costs and other regulatory liabilities		12,973		34,551
Accrued taxes		15,672		13,867
Derivatives		82,334		63,504
Liabilities held for sale		0		1,621
Other		41,991		46,025
Total current liabilities		1,026,926		982,914
Deferred Credits
Unamortized investment tax credits		163,493		135,673
Deferred income taxes		726,763		672,963
Accrued pensions and benefits		228,377		176,128
Asset retirement obligations		203,105		200,732
Regulatory liabilities
Accrued asset removal costs		310,788		325,496
Other post-retirement benefits		113,875		104,382
Other		14,450		17,067
Derivatives		304,198		322,259
Other		118,287		108,124
Total deferred credits		2,183,336		2,062,824
Commitments and Contingencies (Note 13)
Total Capitalization and Liabilities		6,058,705		5,261,359
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Property, Plant and Equipment
Net property, plant and equipment	[1]	13,200
Washington Gas Light Company
Property, Plant and Equipment
At original cost		4,874,905		4,521,535
Accumulated depreciation and amortization		(1,348,173)		(1,278,089)
Net property, plant and equipment		3,526,732		3,243,446
Current Assets
Cash and cash equivalents		1		1
Receivables
Accounts receivable		140,457		126,356
Gas costs and other regulatory assets		15,294		5,797
Unbilled revenues		89,945		21,027
Allowance for doubtful accounts		(20,220)		(19,254)
Net receivables		225,476		133,926
Materials and supplies—principally at average cost		18,368		21,356
Storage gas		82,473		94,489
Prepaid taxes		16,826		30,365
Other prepayments		10,924		11,899
Receivables from associated companies		13,799		3,176
Derivatives		7,285		4,588
Assets held for sale		0		22,906
Other		51		0
Total current assets		375,203		322,706
Deferred Charges and Other Assets
Gas costs		179,856		190,676
Pension and other post-retirement benefits		221,971		210,811
Other		98,527		79,946
Prepaid post-retirement benefits		179,675		137,754
Derivatives		25,590		13,155
Other		8,877		5,638
Total deferred charges and other assets		714,496		637,980
Total Assets		4,616,431		4,204,132
Capitalization
WGL Holdings common shareholders’ equity		1,113,446		1,081,292
Washington Gas Light Company preferred stock		28,173		28,173
Long-term debt		945,891		695,885
Total capitalization		2,087,510		1,805,350
Current Liabilities
Current maturities of long-term debt		0		25,000
Notes payable		104,385		89,000
Accounts payable and other accrued liabilities		204,980		159,280
Wages payable		16,235		19,456
Accrued interest		3,758		4,023
Dividends declared		21,453		20,269
Customer deposits and advance payments		80,936		88,450
Gas costs and other regulatory liabilities		12,973		34,551
Accrued taxes		17,639		11,659
Payables to associated companies		65,770		68,623
Derivatives		58,295		33,856
Liabilities held for sale		0		1,621
Other		7,193		7,013
Total current liabilities		593,617		562,801
Deferred Credits
Unamortized investment tax credits		4,851		5,646
Deferred income taxes		763,720		668,764
Accrued pensions and benefits		226,339		174,318
Asset retirement obligations		199,377		198,938
Regulatory liabilities
Accrued asset removal costs		310,788		325,496
Other post-retirement benefits		113,169		103,683
Other		14,450		17,067
Derivatives		232,040		269,661
Other		70,570		72,408
Total deferred credits		1,935,304		1,835,981
Commitments and Contingencies (Note 13)
Total Capitalization and Liabilities		$ 4,616,431		$ 4,204,132
[1]	Property, plant and equipment include $13.2 million related to SFGF. See Note 17—Other investments of the Notes to Consolidated Financial Statements.

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
OPERATING REVENUES
Utility		$ 1,044,117	$ 1,303,044	$ 1,416,951
Non-utility		1,305,442	1,356,786	1,363,996
Total Operating Revenues	[1]	2,349,559	2,659,830	2,780,947
OPERATING EXPENSES
Utility cost of gas		245,189	510,900	700,305
Non-utility cost of energy-related sales		1,123,077	1,218,331	1,255,279
Operation and maintenance		401,776	395,770	365,873
Depreciation and amortization		132,566	121,892	110,772
General taxes and other assessments		146,655	152,164	151,196
Total Operating Expenses		2,049,263	2,399,057	2,583,425
OPERATING INCOME		300,296	260,773	197,522
Equity in earnings of unconsolidated affiliates		13,806	5,468	3,194
Other income (expense) —net		4,646	653	1,536
Interest expense		52,310	50,511	37,738
INCOME BEFORE INCOME TAXES		266,438	216,383	164,514
INCOME TAX EXPENSE		98,074	83,804	57,254
NET INCOME		168,364	132,579	107,260
Net Income (Loss) Attributable to Noncontrolling Interest		(550)	0	0
Dividends on Washington Gas Light Company preferred stock		1,320	1,320	1,320
NET INCOME APPLICABLE TO COMMON STOCK		$ 167,594	$ 131,259	$ 105,940
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Basic (in shares)		50,369	49,794	51,759
Diluted (in shares)		50,564	50,060	51,770
EARNINGS PER AVERAGE COMMON SHARE
Basic		$ 3.33	$ 2.64	$ 2.05
Diluted		3.31	2.62	2.05
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)		$ 1.9250	$ 1.8275	$ 1.7400
Washington Gas Light Company
OPERATING REVENUES
Total Operating Revenues		$ 1,070,904	$ 1,328,191	$ 1,443,800
OPERATING EXPENSES
Utility cost of gas		271,975	536,027	726,879
Operation and maintenance		325,726	323,967	294,613
Depreciation and amortization		114,605	108,902	102,713
General taxes and other assessments		130,231	136,911	137,472
Total Operating Expenses		842,537	1,105,807	1,261,677
OPERATING INCOME		228,367	222,384	182,123
Other income (expense) —net		(2,143)	(487)	862
Interest expense		41,444	41,828	37,127
INCOME BEFORE INCOME TAXES		184,780	180,069	145,858
INCOME TAX EXPENSE		71,666	71,391	47,534
NET INCOME		113,114	108,678	98,324
Dividends on Washington Gas Light Company preferred stock		1,320	1,320	1,320
NET INCOME APPLICABLE TO COMMON STOCK		$ 111,794	$ 107,358	$ 97,004
[1]	Operating revenues are reported gross of revenue taxes. Revenue taxes of both the regulated utility and the retail energy-marketing segments include gross receipt taxes. Revenue taxes of the regulated utility segment also include public service commission fees, franchise fees and energy 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 - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
NET INCOME	$ 168,364		$ 132,579		$ 107,260
OTHER COMPREHENSIVE INCOME (LOSS), BEFORE INCOME TAXES:
Qualified cash flow hedging instruments	(39,289)	[1]	(11,309)	[1]	(1,548)
Pension and other post-retirement benefit plans
Change in prior service (cost) credit	(891)	[2]	696	[2]	6,095
Change in actuarial net gain (loss)	(936)	[2]	(1,195)	[2]	1,594
TOTAL OTHER COMPREHENSIVE INCOME (LOSS) BEFORE TAXES	(41,116)		(11,808)		6,141
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME (LOSS)	(16,813)		(5,533)		3,054
OTHER COMPREHENSIVE INCOME (LOSS)	(24,303)		(6,275)		3,087
Comprehensive Income	144,061		126,304		110,347
Comprehensive Income (Loss) Attributable to Noncontrolling Interests	(550)		0		0
Dividends on Washington Gas Light Company preferred stock	1,320		1,320		1,320
Comprehensive Income (Loss) Attributable to WGL Holdings, Inc.	143,291		124,984		109,027
Washington Gas Light Company
NET INCOME	113,114		108,678		98,324
Pension and other post-retirement benefit plans
Change in prior service (cost) credit	(891)	[3]	696	[3]	6,095
Change in actuarial net gain (loss)	(936)	[3]	(1,195)	[3]	1,594
Total pension and other post-retirement benefit plans	(1,827)		(499)		7,689
TOTAL OTHER COMPREHENSIVE INCOME (LOSS) BEFORE TAXES	(1,827)		(499)
INCOME TAX EXPENSE (BENEFIT) RELATED TO OTHER COMPREHENSIVE INCOME (LOSS)	(709)		(200)		3,054
OTHER COMPREHENSIVE INCOME (LOSS)	(1,118)		(299)		4,635
Comprehensive Income	111,996		108,379		102,959
Dividends on Washington Gas Light Company preferred stock	$ 1,320		$ 1,320		$ 1,320
[1]	Cash flow hedging instruments represent interest rate swap agreements related to debt issuances. Refer to Note 14—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 10—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 10—Pension and other post-retirement benefit plans for additional details.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
OPERATING ACTIVITIES
Net income (loss)	$ 168,364	$ 132,579	$ 107,260
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and amortization	132,566	121,892	110,772
Amortization of:
Other regulatory assets and liabilities—net	1,909	1,305	610
Debt related costs	1,284	1,187	886
Deferred income taxes-net	163,879	104,405	25,795
Accrued/deferred pension and other post-retirement benefit cost	19,548	25,572	33,384
Earnings in equity interests	(13,806)	(5,066)	(3,194)
Compensation expense related to stock-based awards	12,308	16,478	4,105
Provision for doubtful accounts	13,036	18,197	14,252
Impairment loss	4,110	5,625	2,639
Other non-cash charges (credits)—net	(1,308)	(3,903)	(3,079)
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable and unbilled revenues—net	(105,720)	(71,514)	(1,769)
Gas costs and other regulatory assets/liabilities—net	(31,075)	9,943	2,623
Storage gas	4,311	122,159	13,689
Prepaid Taxes	(76,779)	(38,630)	(42,128)
Accounts payable and other accrued liabilities	33,470	21,841	21,326
Customer deposits and advance payments	(2,513)	20,579	1,164
Accrued taxes	1,805	(266)	(1,923)
Unamortized investment tax credits	27,820	36,322	56,639
Other current assets	(10,533)	5,583	(16,130)
Other current liabilities	(8,774)	13,583	(1,062)
Deferred gas costs—net	10,820	670	(97,383)
Deferred assets—other	(22,312)	(10,153)	(7,525)
Deferred liabilities—other	(31,236)	(34,902)	64
Derivatives	(56,985)	24,468	178,104
Pension and other post-retirement benefits	(10,244)	(14,546)	(16,602)
Other—net	3,821	651	(350)
Net Cash Provided by Operating Activities	227,766	504,059	382,167
FINANCING ACTIVITIES
Common stock issued	78,287	0	714
Long-term debt issued	498,125	298,227	175,253
Long-term debt retired	(25,000)	(20,000)	(67,000)
Debt issuance costs	(445)	(3,497)	(1,543)
Notes payable issued (retired)—net	(63,000)	(121,500)	80,400
Noncontrolling Interest	959	0	0
Project financing	38,468	0	0
Dividends on common stock and preferred stock	(92,841)	(91,316)	(85,901)
Repurchase of common stock	0	(41,485)	(56,136)
Other financing activities—net	1,986	(1,457)	(560)
Net Cash Provided by (Used in) Financing Activities	436,539	18,972	45,227
INVESTING ACTIVITIES
Capital expenditures (excluding AFUDC)	(530,385)	(464,291)	(394,762)
Investments in non-utility interests	(158,052)	(67,447)	(31,415)
Distributions and receipts from non-utility interests	8,254	10,780	4,116
Net proceeds from sale of assets	19,749	0	0
Loans to external parties	(5,031)	(4,151)	0
Net Cash Used in Investing Activities	(665,465)	(525,109)	(422,061)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(1,160)	(2,078)	5,333
Cash and Cash Equivalents at Beginning of Year	6,733	8,811	3,478
Cash and Cash Equivalents at End of Year	5,573	6,733	8,811
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid (refunded)—net	(10,723)	6,935	20,110
Interest paid	51,838	45,654	36,991
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Project debt financing activities-net	0	(8,350)	253
Capital expenditure accruals included in accounts payable and other accrued liabilities	84,132	45,780	55,164
Dividends paid in common stock	4,011	0	5,312
Stock Issued	6,742	1,009	2,244
Washington Gas Light Company
OPERATING ACTIVITIES
Net income (loss)	113,114	108,678	98,324
ADJUSTMENTS TO RECONCILE NET INCOME TO NET CASH PROVIDED BY OPERATING ACTIVITIES
Depreciation and amortization	114,605	108,902	102,713
Amortization of:
Other regulatory assets and liabilities—net	1,909	1,305	610
Debt related costs	1,191	1,275	886
Deferred income taxes-net	123,482	76,621	7,050
Accrued/deferred pension and other post-retirement benefit cost	19,497	24,757	33,670
Compensation expense related to stock-based awards	11,452	14,958	3,185
Provision for doubtful accounts	10,945	12,734	11,839
Impairment loss	0	0	2,639
Other non-cash charges (credits)—net	(197)	1,679	8,838
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable and unbilled revenues—net	(78,304)	(16,127)	(39,253)
Gas costs and other regulatory assets/liabilities—net	(31,075)	9,943	2,623
Storage gas	12,016	61,594	(23,857)
Prepaid Taxes	13,539	(14,228)	(1,269)
Accounts payable and other accrued liabilities	31,408	(1,007)	49,429
Customer deposits and advance payments	(7,514)	20,132	1,164
Accrued taxes	5,980	(12,951)	(770)
Other current assets	3,912	4,958	(5,089)
Other current liabilities	(4,486)	1,435	(526)
Deferred gas costs—net	10,820	670	(97,383)
Deferred assets—other	(22,057)	(10,036)	(10,073)
Deferred liabilities—other	(56,822)	(13,912)	(3,007)
Derivatives	(28,314)	4,466	170,744
Pension and other post-retirement benefits	(10,251)	(13,750)	(16,973)
Other—net	2,107	258	(359)
Net Cash Provided by Operating Activities	236,957	372,354	295,155
FINANCING ACTIVITIES
Long-term debt issued	248,125	50,000	175,253
Long-term debt retired	(25,000)	(20,000)	(67,000)
Debt issuance costs	(333)	(741)	(1,543)
Notes payable issued (retired)—net	(47,000)	0	(35,500)
Project financing	38,468	0	0
Dividends on common stock and preferred stock	(83,116)	(79,763)	(79,665)
Other financing activities—net	2,891	0	(1,749)
Net Cash Provided by (Used in) Financing Activities	134,035	(50,504)	(10,204)
INVESTING ACTIVITIES
Capital expenditures (excluding AFUDC)	(390,741)	(322,909)	(283,891)
Net proceeds from sale of assets	19,749	0	0
Net Cash Used in Investing Activities	(370,992)	(322,909)	(283,891)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	0	(1,059)	1,060
Cash and Cash Equivalents at Beginning of Year	1	1,060	0
Cash and Cash Equivalents at End of Year	1	1	1,060
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Income taxes paid (refunded)—net	(19,004)	8,902	19,007
Interest paid	40,972	36,971	36,380
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Project debt financing activities-net	0	(8,350)	253
Capital expenditure accruals included in accounts payable and other accrued liabilities	$ 43,687	$ 40,926	$ 46,331

Consolidated Statements of Capi

Consolidated Statements of Capitalization - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Common Shareholders' Equity
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (38,539)	$ (14,236)
WGL Holdings common shareholders' equity	1,375,561	1,243,247
Non-controlling Interest	409	0
Total Equity	1,404,143	1,271,420
Total capitalization	$ 2,848,443	$ 2,215,621
Total Capitalization As Percentage	100.00%	100.00%
Preferred Stock
Preferred Stock, Value, Issued	$ 0	$ 0
Preferred stock	$ 28,173	$ 28,173
Preferred stock, percentage of total capitalization	1.00%	1.30%
Long-Term Debt
Medium Term Notes	$ 1,446,000	$ 971,000
Unamortized discount	(1,700)	(1,799)
Less-current maturities	0	25,000
Total Long-term debt	$ 1,444,300	$ 944,201
Long Term Debt As Percentage Of Total Capitalization	50.70%	42.60%
Non-controlling Interest
Common Shareholders' Equity
Non-controlling Interest	$ 409	$ 0
Non-controlling Interest, percentage of total capitalization	0.10%	0.00%
Total Equity
Common Shareholders' Equity
Total Equity	$ 1,404,143	$ 1,271,420
Total equity, percentage of total capitalization	49.30%	57.40%
Due fiscal year 2016
Long-Term Debt
Medium Term Notes		$ 25,000
Due fiscal year 2018
Long-Term Debt
Medium Term Notes	$ 250,000
Due fiscal year 2019
Long-Term Debt
Medium Term Notes	50,000	50,000
Due fiscal year 2020
Long-Term Debt
Medium Term Notes	150,000	150,000
Due fiscal year 2023
Long-Term Debt
Medium Term Notes	20,000	20,000
Due fiscal year 2025
Long-Term Debt
Medium Term Notes	40,500	40,500
Due fiscal year 2027
Long-Term Debt
Medium Term Notes	125,000	125,000
Due fiscal year 2028
Long-Term Debt
Medium Term Notes	52,000	52,000
Due fiscal year 2030
Long-Term Debt
Medium Term Notes	8,500	8,500
Due fiscal year 2036
Long-Term Debt
Medium Term Notes	50,000	50,000
Due fiscal year 2041
Long-Term Debt
Medium Term Notes	75,000	75,000
Due fiscal year 2044
Long-Term Debt
Medium Term Notes	175,000	175,000
Due fiscal year 2045
Long-Term Debt
Medium Term Notes	200,000	200,000
Due fiscal year 2046
Long-Term Debt
Medium Term Notes	250,000
Common Stock
Common Shareholders' Equity
Common stock, value	574,496	485,456
Paid-in capital	12,519	14,934
Retained earnings	827,085	757,093
Accumulated Other Comprehensive Income (Loss), Net of Tax	(38,539)	(14,236)
WGL Holdings common shareholders' equity	$ 1,375,561	$ 1,243,247
Common shareholders' equity, percentage of total capitalization	48.20%	56.10%
$4.80 series
Preferred Stock
Preferred stock	$ 15,000	$ 15,000
$4.25 series
Preferred Stock
Preferred stock	7,173	7,173
$5.00 series
Preferred Stock
Preferred stock	6,000	6,000
Washington Gas Light Company
Common Shareholders' Equity
Accumulated Other Comprehensive Income (Loss), Net of Tax	(7,830)	(6,712)
WGL Holdings common shareholders' equity	1,113,446	1,081,292
Total capitalization	$ 2,087,510	$ 1,805,350
Total Capitalization As Percentage	100.00%	100.00%
Preferred Stock
Preferred stock	$ 28,173	$ 28,173
Long-Term Debt
Medium Term Notes	946,000	721,000
Unamortized discount	(109)	(115)
Less-current maturities	0	(25,000)
Total Long-term debt	$ 945,891	$ 695,885
Long Term Debt As Percentage Of Total Capitalization	45.30%	38.50%
Washington Gas Light Company | Due fiscal year 2016
Long-Term Debt
Medium Term Notes		$ 25,000
Washington Gas Light Company | Due fiscal year 2019
Long-Term Debt
Medium Term Notes	$ 50,000	50,000
Washington Gas Light Company | Due fiscal year 2020
Long-Term Debt
Medium Term Notes	50,000	50,000
Washington Gas Light Company | Due fiscal year 2023
Long-Term Debt
Medium Term Notes	20,000	20,000
Washington Gas Light Company | Due fiscal year 2025
Long-Term Debt
Medium Term Notes	40,500	40,500
Washington Gas Light Company | Due fiscal year 2027
Long-Term Debt
Medium Term Notes	125,000	125,000
Washington Gas Light Company | Due fiscal year 2028
Long-Term Debt
Medium Term Notes	52,000	52,000
Washington Gas Light Company | Due fiscal year 2030
Long-Term Debt
Medium Term Notes	8,500	8,500
Washington Gas Light Company | Due fiscal year 2036
Long-Term Debt
Medium Term Notes	50,000	50,000
Washington Gas Light Company | Due fiscal year 2041
Long-Term Debt
Medium Term Notes	75,000	75,000
Washington Gas Light Company | Due fiscal year 2044
Long-Term Debt
Medium Term Notes	175,000	175,000
Washington Gas Light Company | Due fiscal year 2045
Long-Term Debt
Medium Term Notes	50,000	50,000
Washington Gas Light Company | Due fiscal year 2046
Long-Term Debt
Medium Term Notes	250,000
Washington Gas Light Company | Common Stock
Common Shareholders' Equity
Common stock, value	46,479	46,479
Paid-in capital	488,135	483,677
Retained earnings	586,662	557,848
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (7,830)	$ (6,712)
Common shareholders' equity, percentage of total capitalization	53.30%	59.90%
Total Common Shareholder's Equity	$ 1,113,446	$ 1,081,292
Washington Gas Light Company | Preferred Stock
Preferred Stock
Preferred stock	$ 28,173	$ 28,173
Preferred stock, percentage of total capitalization	1.40%	1.60%
Washington Gas Light Company | $4.80 series
Preferred Stock
Preferred stock	$ 15,000	$ 15,000
Washington Gas Light Company | $4.25 series
Preferred Stock
Preferred stock	7,173	7,173
Washington Gas Light Company | $5.00 series
Preferred Stock
Preferred stock	$ 6,000	$ 6,000

Consolidated Statements of Cap7

Consolidated Statements of Capitalization - (Parenthetical) - $ / shares	Sep. 30, 2016	Sep. 30, 2015
Common Shareholders' Equity
Common Stock, Par or Stated Value Per Share	$ 0	$ 0
Common Stock, Shares Authorized	120,000,000	120,000,000
Common Stock, Shares, Issued	51,080,612	49,728,662
Preferred Stock [Abstract]
Preferred Stock, Shares Authorized	3,000,000	3,000,000
Preferred Stock, Issued	0	0
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0	$ 0
Due fiscal year 2016
Schedule of Capitalization [Line Items]
Note Rate		5.17%
Due fiscal year 2018
Schedule of Capitalization [Line Items]
Note Rate	1.34%
Due fiscal year 2019
Schedule of Capitalization [Line Items]
Note Rate	7.46%	7.46%
Due fiscal year 2020 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	4.76%	4.76%
Due fiscal year 2020 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	2.25%	2.25%
Due fiscal year 2023
Schedule of Capitalization [Line Items]
Note Rate	6.65%	6.65%
Due fiscal year 2025
Schedule of Capitalization [Line Items]
Note Rate	5.44%	5.44%
Due fiscal year 2027 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	6.82%	6.82%
Due fiscal year 2027 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	6.40%	6.40%
Due fiscal year 2028 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	6.85%	6.85%
Due fiscal year 2028 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	6.57%	6.57%
Due fiscal year 2030
Schedule of Capitalization [Line Items]
Note Rate	7.50%	7.50%
Due fiscal year 2036 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	5.78%	5.78%
Due fiscal year 2036 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	5.70%	5.70%
Due fiscal year 2041
Schedule of Capitalization [Line Items]
Note Rate	5.21%	5.21%
Due fiscal year 2044 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	5.00%	5.00%
Due fiscal year 2044 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	4.22%	4.22%
Due fiscal year 2045 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	4.60%	4.60%
Due fiscal year 2045 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	4.24%	4.24%
Due fiscal year 2046
Schedule of Capitalization [Line Items]
Note Rate	3.80%
Washington Gas Light Company
Preferred Stock [Abstract]
Preferred Stock, Shares Authorized	1,500,000	1,500,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0	$ 0
Washington Gas Light Company | Due fiscal year 2016
Schedule of Capitalization [Line Items]
Note Rate		5.17%
Washington Gas Light Company | Due fiscal year 2019
Schedule of Capitalization [Line Items]
Note Rate	7.46%	7.46%
Washington Gas Light Company | Due fiscal year 2020
Schedule of Capitalization [Line Items]
Note Rate	4.76%	4.76%
Washington Gas Light Company | Due fiscal year 2023
Schedule of Capitalization [Line Items]
Note Rate	6.65%	6.65%
Washington Gas Light Company | Due fiscal year 2025
Schedule of Capitalization [Line Items]
Note Rate	5.44%	5.44%
Washington Gas Light Company | Due fiscal year 2027 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	6.82%	6.82%
Washington Gas Light Company | Due fiscal year 2027 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	6.40%	6.40%
Washington Gas Light Company | Due fiscal year 2028 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	6.85%	6.85%
Washington Gas Light Company | Due fiscal year 2028 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	6.57%	6.57%
Washington Gas Light Company | Due fiscal year 2030
Schedule of Capitalization [Line Items]
Note Rate	7.50%	7.50%
Washington Gas Light Company | Due fiscal year 2036 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	5.78%	5.78%
Washington Gas Light Company | Due fiscal year 2036 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	5.70%	5.70%
Washington Gas Light Company | Due fiscal year 2041
Schedule of Capitalization [Line Items]
Note Rate	5.21%	5.21%
Washington Gas Light Company | Due fiscal year 2044 | Maximum
Schedule of Capitalization [Line Items]
Note Rate	5.00%	5.00%
Washington Gas Light Company | Due fiscal year 2044 | Minimum
Schedule of Capitalization [Line Items]
Note Rate	4.22%	4.22%
Washington Gas Light Company | Due fiscal year 2045
Schedule of Capitalization [Line Items]
Note Rate	4.24%
Washington Gas Light Company | Due fiscal year 2046
Schedule of Capitalization [Line Items]
Note Rate	3.80%
Common Stock | Washington Gas Light Company
Common Shareholders' Equity
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares Authorized	80,000,000	80,000,000
Common Stock, Shares, Issued	46,479,536	46,479,536
Preferred Stock | Washington Gas Light Company
Preferred Stock [Abstract]
Preferred Stock, Shares Authorized	1,500,000	1,500,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0	$ 0
$4.80 series
Preferred Stock [Abstract]
Preferred Stock, Shares Outstanding (in shares)	150,000	150,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 4.80	$ 4.80
$4.80 series | Washington Gas Light Company
Preferred Stock [Abstract]
Preferred Stock, Shares Outstanding (in shares)	150,000	150,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 4.80	$ 4.80
$4.25 series
Preferred Stock [Abstract]
Preferred Stock, Shares Outstanding (in shares)	70,600	70,600
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 4.25	$ 4.25
$4.25 series | Washington Gas Light Company
Preferred Stock [Abstract]
Preferred Stock, Shares Outstanding (in shares)	70,600	70,600
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 4.25	$ 4.25
$5.00 series
Preferred Stock [Abstract]
Preferred Stock, Shares Outstanding (in shares)	60,000	60,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 5	$ 5
$5.00 series | Washington Gas Light Company
Preferred Stock [Abstract]
Preferred Stock, Shares Outstanding (in shares)	60,000	60,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 5	$ 5

Consolidated Statements of Comm

Consolidated Statements of Common Shareholders Equity - USD ($) $ in Thousands		Total	WGLCommon Stock		WGLPaid-In Capital		WGLRetained Earnings		WGLAccumulated Other Comprehensive Loss, Net of Taxes	WGLWGL Common Shareholders' Equity		WGLNon-controlling Interest	WGLWashington Gas Light Company Preferred Stock	WGLTotal Equity		Washington Gas Light Company	Washington Gas Light CompanyCommon Stock	Washington Gas Light CompanyPaid-In Capital		Washington Gas Light CompanyRetained Earnings	Washington Gas Light CompanyAccumulated Other Comprehensive Loss, Net of Taxes	Washington Gas Light CompanyTotal		Common Stock	Common StockWashington Gas Light Company
NET INCOME APPLICABLE TO COMMON STOCK		$ 105,940														$ 97,004
Beginning Balance, shares at Sep. 30, 2013			51,774,204														46,479,536
Common shareholders' equity, beginning balance at Sep. 30, 2013			$ 574,461		$ 10,710		$ 700,422		$ (11,048)	$ 1,274,545			$ 28,173				$ 46,479	$ 477,968		$ 511,184	$ (11,048)	$ 1,024,583
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, beginning balance at Sep. 30, 2013														$ 1,302,718
Net income (loss)		107,260								105,940						98,324				98,324		98,324
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest														107,260
Non-controlling interest net income		0
OTHER COMPREHENSIVE INCOME (LOSS)		3,087							3,087	3,087				3,087		4,635					4,635	4,635
Dividend reinvestment			$ 4,649							4,649				4,649
Dividend reinvestment, shares			114,883
Repurchase of common stock			$ (56,136)							(56,136)				(56,136)
Repurchase of common stock, shares			(1,304,504)
Stock-based compensation			$ 2,958		1,137					4,095				4,095				2,652	[1]			2,652	[1]
Stock-based compensation, Shares			71,970
Preferred Stock Dividends, Income Statement Impact													1,320
Dividends Abstract
Common Stock							(89,604)			(89,604)				(89,604)						(78,708)		(78,708)
Preferred Stock													(1,320)	(1,320)						(1,320)		(1,320)
Common shareholders' equity, ending balance at Sep. 30, 2014			$ 525,932		11,847		716,758		(7,961)	1,246,576			28,173				$ 46,479	480,620		529,480	(6,413)	1,050,166
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, ending balance at Sep. 30, 2014														1,274,749
Ending Balance, shares at Sep. 30, 2014			50,656,553														46,479,536
NET INCOME APPLICABLE TO COMMON STOCK		131,259														107,358
Net income (loss)		132,579								131,259						108,678				108,678		108,678
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest														132,579
Non-controlling interest net income		0
OTHER COMPREHENSIVE INCOME (LOSS)		(6,275)								(6,275)				(6,275)		(299)					(299)	(299)
Repurchase of common stock			$ (41,485)							(41,485)				(41,485)
Repurchase of common stock, shares			(948,604)
Stock-based compensation			$ 1,009		3,087					4,096				4,096				3,057	[1]			3,057	[1]
Stock-based compensation, Shares			20,713
Preferred Stock Dividends, Income Statement Impact													1,320
Dividends Abstract
Common Stock							(90,924)			(90,924)				(90,924)						(78,990)		(78,990)
Preferred Stock													(1,320)	(1,320)						(1,320)		(1,320)
Common shareholders' equity, ending balance at Sep. 30, 2015		1,243,247	$ 485,456		14,934		757,093		(14,236)	1,243,247			28,173			1,081,292	$ 46,479	483,677		557,848	(6,712)	1,081,292		$ 1,243,247
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, ending balance at Sep. 30, 2015														1,271,420											$ 1,081,292
Ending Balance, shares at Sep. 30, 2015			49,728,662														46,479,536
NET INCOME APPLICABLE TO COMMON STOCK		167,594														111,794
Net income (loss)		168,364					167,594			167,594						113,114				113,114		113,114
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest														168,364
Non-controlling interest net income		(550)										$ (550)
OTHER COMPREHENSIVE INCOME (LOSS)		(24,303)							(24,303)	(24,303)				(24,303)		(1,118)					(1,118)	(1,118)
Stock-based compensation			$ 6,742	[2]	(2,415)	[2]	(164)	[2]		4,163	[2]			4,163	[2]			4,458	[1]			4,458	[1]
Stock-based compensation, Shares	[2]		115,974
Issuance of common stock, value	[3]		$ 82,298							82,298				82,298
Issuance of common stock (in shares)	[3]		1,235,976
Preferred Stock Dividends, Income Statement Impact													1,320
Dividends Abstract
Common Stock							(97,438)			(97,438)				(97,438)						(82,980)		(82,980)
Preferred Stock													(1,320)	(1,320)						(1,320)		(1,320)
Common shareholders' equity, ending balance at Sep. 30, 2016		$ 1,375,561	$ 574,496		$ 12,519		$ 827,085		$ (38,539)	$ 1,375,561		409	$ 28,173			$ 1,113,446	$ 46,479	$ 488,135		$ 586,662	$ (7,830)	$ 1,113,446		$ 1,375,561
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, ending balance at Sep. 30, 2016														1,404,143											$ 1,113,446
Ending Balance, shares at Sep. 30, 2016			51,080,612														46,479,536
Acquisition of non-controlling Interest												$ 959		$ 959
[1]	Stock-based compensation is based on the stock awards of WGL that are allocated to Washington Gas Light Company for its pro-rata share.
[2]	Includes dividend equivalents related to our performance shares.
[3]	Includes shares issued under the ATM program and the dividend reinvestment and common stock purchase plans.

Consolidated Statements of Com9

Consolidated Statements of Common Shareholders Equity (Parenthetical) - $ / shares	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
DIVIDENDS DECLARED PER COMMON SHARE (in dollars per share)	$ 1.9250	$ 1.8275	$ 1.7400

Accounting Policies

Accounting Policies	12 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Accounting Policies	NOTE 1. ACCOUNTING POLICIES GENERAL WGL Holdings, Inc. (WGL) is a holding company that owns all of the shares of common stock of Washington Gas Light Company (Washington Gas), a regulated natural gas utility, and all of the shares of common stock of Washington Gas Resources Corporation (Washington Gas Resources), and Hampshire Gas Company (Hampshire). Washington Gas Resources owns all of the shares of common stock of four non-utility subsidiaries that include WGL Energy Services, Inc. (WGL Energy Services), WGL Energy Systems, Inc. (WGL Energy Systems), WGL Midstream, Inc. (WGL Midstream) and WGSW, Inc. (WGSW). Except where the content clearly indicates otherwise, “WGL,” “we,” “us” or “our” refers to the holding company or the consolidated entity of WGL Holdings, Inc. and all of its subsidiaries. Unless otherwise noted, these notes apply equally to WGL and Washington Gas. NATURE OF OPERATIONS Washington Gas and Hampshire comprise our regulated utility segment. Washington Gas is a public utility that sells and delivers natural gas to more than one million customers primarily in the District of Columbia and the surrounding metropolitan areas in Maryland and Virginia. Deliveries to firm residential and commercial customers accounted for 70% of the total therms delivered to customers by Washington Gas in the fiscal year ended September 30, 2016 . Deliveries to interruptible customers accounted for 13% and deliveries to customers who use natural gas to generate electricity accounted for 16% . These amounts do not include deliveries related to Washington Gas’ asset optimization program discussed below. Hampshire operates an underground natural gas storage facility that provides services exclusively to Washington Gas. Hampshire is regulated under a cost of service tariff by the Federal Energy Regulatory Commission (FERC). The retail energy-marketing segment consists of WGL Energy Services which competes with regulated utilities and other unregulated third party marketers to sell natural gas and electricity directly to residential, commercial, industrial and governmental customers with the objective of earning a profit through competitive pricing. The commodities that WGL Energy Services sells are delivered to retail customers through assets owned by regulated utilities. Washington Gas delivers the majority of natural gas sold by WGL Energy Services, and unaffiliated electric utilities deliver all of the electricity sold. WGL Energy Services owned multiple solar PV distributed generation assets at September 30, 2016 , though the results from these activities are presented in the commercial energy systems segment. Other than these facilities, WGL Energy Services does not own or operate any other natural gas or electric generation, production, transmission or distribution assets. At September 30, 2016 , WGL Energy Services served approximately 133,000 natural gas customers and approximately 127,400 electricity customers located in Maryland, Virginia, Delaware, Pennsylvania and the District of Columbia. The commercial energy systems segment consists of WGL Energy Systems, WGSW and the results of operations of affiliate-owned commercial distributed energy projects. This segment focuses on clean and energy efficient solutions for its customers, driving earnings through: (i) upgrading the mechanical, electrical, water and energy-related infrastructure of large governmental and commercial facilities by implementing both traditional and alternative energy technologies; (ii) owning and operating distributed generation assets such as solar PV systems, combined heat and power plants, and natural gas fuel cells and (iii) passive investments in residential and commercial retail solar PV companies. In addition to our primary markets, this segment provides customized energy solutions across a much wider footprint, with business activities across the United States. The midstream energy services segment, which consists of the operations of WGL Midstream, specializes in the investment, management, development and optimization of natural gas storage and transportation midstream infrastructure projects. WGL Midstream enters into both physical and financial transactions in a manner intended to utilize energy risk management products to mitigate risks while seeking to maximize potential profits from the optimization of the transportation and storage assets it has under contract. Refer to Note 16— Operating Segment Reporting for further discussion of our segments. CONSOLIDATION OF FINANCIAL STATEMENTS The consolidated financial statements include the accounts of WGL and its subsidiaries during the fiscal years reported. Certain prior period amounts have been recast to conform to current period presentation. Refer to Note 9— Income Taxes , for a further discussion of prior year amounts reclassified as a result of the implementation of Income Taxes (Topic 740): Balance sheet Classification of Deferred Taxes , which was implemented retrospectively in the first quarter of fiscal year 2016. Inter-company transactions have been eliminated. Refer to Note 18— Related Party Transactions for a discussion of inter-company transactions. WGL has a variable interest in five investments that qualify as variable interest entities (VIEs). At September 30, 2016 , WGL and its subsidiaries are not the primary beneficiary for four of the five VIEs; therefore, we have not consolidated those VIE entities. WGSW is the primary beneficiary for one of the VIEs, SFGF, LLC (SFGF) and accordingly, it has been consolidated. Refer to Note 17— Other Investments for a discussion of VIEs and other investments. USE OF ESTIMATES IN THE PREPARATION OF FINANCIAL STATEMENTS In accordance with generally accepted accounting principles in the United States of America (GAAP), we make certain estimates and assumptions regarding: (i) reported assets and liabilities; (ii) disclosed contingent assets and liabilities at the date of the financial statements and (iii) reported revenues, revenues subject to refund, and expenses during the reporting period. Actual results could differ from those estimates. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment (comprised principally of utility plant) are stated at original cost, including labor, materials, taxes and overhead costs incurred during the construction period. The cost of utility plant of Washington Gas includes an allowance for funds used during construction (AFUDC) that is calculated under a formula prescribed by our regulators in Maryland and the District of Columbia. Washington Gas capitalizes AFUDC as a component of construction overhead. The rates for AFUDC for fiscal years September 30, 2016 , 2015 and 2014 were 5.51% , 4.12% and 3.36% , respectively. Washington Gas charges maintenance and repairs directly to operating expenses. Washington Gas capitalizes betterments and renewal costs, and calculates depreciation applicable to its utility gas plant in service primarily using a straight-line method over the estimated remaining life of the plant. The composite depreciation and amortization rate of the regulated utility segment was 2.70% , 2.73% and 2.77% during fiscal years 2016 , 2015 and 2014 , respectively. In accordance with regulatory requirements, such rates include a component related to asset removal costs for Washington Gas. These asset removal costs are accrued through depreciation expense with a corresponding credit to “Regulatory liabilities—Accrued asset removal costs.” When Washington Gas retires depreciable utility plant and equipment, it charges the associated original costs to “Accumulated depreciation and amortization” and any related removal costs incurred are charged to “Regulatory liabilities—Accrued asset removal costs.” Washington Gas periodically reviews the adequacy of its depreciation rates by considering estimated remaining lives and other factors. For information about Asset Retirement Obligations (ARO’s), refer to the section entitled “Asset Retirement Obligations” . At September 30, 2016 and 2015 , 88.7% and 91.2% , respectively, of WGL’s consolidated original cost of property, plant and equipment was related to the regulated utility segment as shown below. Property, Plant and Equipment at Original Cost ($ In millions) September 30, 2016 2015 Regulated utility segment Distribution, transmission and storage $ 4,210.6 75.9 % $ 3,927.2 78.5 % General, miscellaneous and intangibles 435.2 7.9 424.8 8.5 Construction work in progress (CWIP) 273.1 4.9 210.4 4.2 Total regulated utility segment 4,918.9 88.7 4,562.4 91.2 Unregulated segments 624.1 11.3 441.5 8.8 Total $ 5,543.0 100.0 % $ 5,003.9 100.0 % ASSETS SALE - BUILDING During the year ended September 30, 2016 , Washington Gas completed the sale of the Springfield Operation Center for approximately $ 20.3 million , net of selling and administrative expenses of $ 0.5 million . As a result of the sale, an additional minimal loss was recorded to "Other expense-net" in the accompanying Consolidated Statements of Income. At September 30, 2015, the assets and liabilities associated with the Springfield Operations Center were reported at their expected selling price, less selling expenses, as "Assets held for sale" and "Liabilities held for sale" on WGL's and Washington Gas' balance sheets. IMPAIRMENT OF LONG-LIVED ASSETS Management regularly reviews property and equipment and other long-lived assets, including certain definite-lived intangible assets and our equity method investments for possible impairment. For our equity method investments, an impairment is recorded when the investment has experienced decline in value that is other-than-temporary. Additionally, if the projects in which we hold an investment recognize an impairment loss, we would record our proportionate share of that impairment loss and evaluate the investment for decline in value that is other-than-temporary. This review occurs quarterly, or more frequently if events or changes in circumstances indicate the carrying amount of the asset may not be recoverable. During the fiscal year ended September 30, 2016 , WGL recorded a $ 4.1 million impairment for the Nextility investment in direct financing leases. During the fiscal year ended September 30, 2015 , WGL impaired its entire investment in ASDHI by its carrying value of $ 5.6 million based on management's assumption of the current valuation and expected return from the investment. During the fiscal year ended September 30, 2014 , Washington Gas recorded an impairment charges of $0.8 million in operation and maintenance expense related to its Springfield Operations Center asset and an impairment loss of $1.9 million for the unrecoverable portion of the costs incurred associated with an abandoned LNG storage project. Refer to Note 15 — Fair Value Measurements and Note 17 — Other Investments of the Notes to Consolidated Financial Statements for further discussion of these assets. OPERATING LEASES We have classified the lease of our corporate headquarters as an operating lease. We amortize as rent expense the total of all scheduled lease payments (including lease payment escalations) and tenant allowances on a straight-line basis over the term of the lease. For this purpose, the lease term began on the date when the lessor commenced constructing the leasehold improvements which allowed us to occupy our corporate headquarters. Leasehold improvement costs are classified as “Property, Plant and Equipment” on the Balance Sheets, and are being amortized to depreciation and amortization expense on a straight-line basis over the 15 -year non-cancelable period of the lease. Refer to Note 13— Commitments and Contingencies for financial data for all of our operating leases. CASH AND CASH EQUIVALENTS We consider all investments with original maturities of three months or less to be cash equivalents. We did not have any restrictions on our cash balances that would impact the payment of dividends by WGL or our subsidiaries as of September 30, 2016 and 2015 . REVENUE AND COST RECOGNITION Regulated Utility Operations Revenues. For regulated deliveries of natural gas, Washington Gas reads meters and bills customers on a 19 -day monthly cycle basis. The billing cycles for customers do not coincide with the accounting periods used for financial reporting purposes; therefore, Washington Gas accrues unbilled revenues for gas delivered, but not yet billed, at the end of each accounting period. Cost of Gas. Washington Gas’ jurisdictional tariffs contain mechanisms that provide for the recovery of the cost of gas incurred on behalf of firm customers, including related pipeline transportation and storage capacity charges. Under these mechanisms, Washington Gas periodically adjusts its firm customers’ rates to reflect increases and decreases in these costs. Under or over-collections of gas costs in the current cycle are charged or credited to deferred charges or credits on the balance sheet as non-current regulatory assets or liabilities. Amounts deferred at the end of the cycle, August 31 of each year, are fully reconciled and transferred to current assets or liabilities under the balance sheet captions “Gas costs and other regulatory assets” and “Gas costs and other regulatory liabilities.” These balances are recovered or refunded to customers over the subsequent 12 month period. Revenue Taxes. Revenue taxes such as gross receipts taxes, Public Service Commission (PSC) fees, franchise fees and energy taxes are reported gross in operating revenues. During September 30, 2016, 2015 and 2014 $ 73.0 million and $83.5 million , and $84.3 million , respectively, were recorded to operating revenues. Transportation Gas Imbalance. Interruptible shippers and third party marketer shippers transport gas to Washington Gas’ distribution system as part of the unbundled services offered. The delivered volumes of gas from third party shippers into Washington Gas’ distribution system rarely equal the volumes billed to third party marketer customers, resulting in transportation gas imbalances. These imbalances are usually short-term in duration, and Washington Gas monitors the activity and regularly notifies the shippers when their accounts have an imbalance. In accordance with regulatory treatment, Washington Gas does not record a receivable from or liability to third party marketers associated with gas volumes related to these transportation imbalances but, rather, reflects the financial impact as a regulatory asset or liability related to its gas cost adjustment mechanism, thereby eliminating any profit or loss that would occur as a result of the imbalance. The regulatory treatment combines the imbalance for all marketers, including WGL Energy Services, into a single “net” adjustment to the regulatory asset or liability. Refer to Note 18— Related Party Transactions for further discussion of the accounting for these imbalance transactions. Asset Optimization Program. Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources by entering into physical and financial transactions in the form of forwards, futures and option contracts for periods when these resources are not being used to physically serve utility customers. Refer to “Derivative Activities” below for further discussion of the accounting for derivative transactions entered into under this program. Regulatory sharing mechanisms in all three jurisdictions allow the profit from these transactions to be shared between Washington Gas’ customers and shareholders. All unrealized fair value gains and losses, and margins generated from the physical and financial settlement of these asset optimization contracts are recorded in utility cost of gas or, in the case of amounts to be shared with rate payers, regulatory assets/liabilities. Non-Utility Operations Retail Energy-Marketing Segment. WGL Energy Services sells natural gas and electricity on an unregulated basis to residential, commercial and industrial customers both inside and outside the Washington Gas service territory. WGL Energy Services enters into indexed or fixed-rate contracts with residential, commercial and industrial customers for sales of natural gas and electricity. Customer contracts, which typically have terms less than 24 months, but may extend up to 5 years , allow WGL Energy Services to bill customers based upon metered gas and electricity usage. Usage is measured either on a cycle basis at customer premises or based on quantities delivered to the local utility, both of which may vary by month. The billing cycles for customers do not coincide with the accounting periods used for financial reporting purposes; therefore, WGL Energy Services accrues unbilled revenues for gas and electricity delivered, but not yet billed, at the end of each accounting period. In addition, WGL Energy Services periodically makes spot sales in the wholesale market due to specific delivery requirements or to reduce customer supply costs. Revenues are reflected in “Operating Revenues—Non utility.” WGL Energy Services procures natural gas and electricity supply under contract structures in which it assembles the various components of supply from multiple suppliers to match its customer requirements. The cost of natural gas and electricity for these purchases is recorded using the contracted volumes and prices in “Non-Utility cost of energy-related sales.” Commercial Energy Systems Segment. WGL Energy Systems recognizes income and expenses for all design-build construction contracts using the percentage-of-completion method in “Operating Revenues—Non-utility” and “Non-Utility cost of energy-related sales.” WGL Energy Systems also recognizes income from its distributed energy assets based on the terms of the related power purchase agreements. Renewable Energy Certificates (RECs) are generated by WGL Energy Systems after every 1,000 Kilowatt-hours (kWh) of electricity are produced by an eligible solar facility. WGL Energy Systems recognizes income on the sale of RECs based on the contractual terms and conditions of the sale. Refer to Note 17— Other Investments for discussion of our sale leaseback arrangements and equity method investments. Midstream Energy Services Segment. WGL Midstream nets its revenues and costs related to its trading activities in "Operating Revenues—Non-utility". Any profits and losses from WGL Midstream's pipeline investments are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. Refer to Note 17— Other Investments for discussion of our equity method investments. STORAGE GAS VALUATION METHODS 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. There were no lower-of-cost or market adjustment recorded to net income for Washington Gas the fiscal year ended September 30, 2016 . WGL Midstream recorded quarterly adjustments that netted to zero for the fiscal year ended September 30, 2016 . The following table shows the lower-of-cost or market adjustments recorded to net income for the years ended September 30, 2015 and 2014 . Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income (In millions) September 30, 2015 2014 WGL (a) Operating revenues - non-utility $ (21.5 ) $ (3.0 ) Washington Gas Utility cost of gas $ (1.3 ) $ (0.2 ) Total Consolidated $ (22.8 ) $ (3.2 ) (a) WGL includes WGL Midstream. WEATHER-RELATED INSTRUMENTS Periodically, we purchase certain weather-related instruments, such as HDD derivatives and CDD derivatives. We account for these weather related instruments in accordance with Financial Accounting Standards Board Accounting Standards Codification (ASC) Subtopic 815-45, Derivatives and Hedging — Weather Derivatives . For weather insurance policies and HDD derivatives, benefits or costs are ultimately recognized to the extent actual HDDs fall above or below the contractual HDDs for each instrument. Benefits or costs are recognized for CDD derivatives when the average temperature exceeds or is below a contractually stated level during the contract period. Premiums for weather-related instruments are amortized based on the pattern of normal temperature days over the coverage period. Weather-related instruments for which we collect a premium are carried at fair value. Refer to Note 14— Derivative and Weather-Related Instruments for further discussion of our weather-related instruments. DERIVATIVE ACTIVITIES Regulated Utility . Washington Gas enters into both physical and financial derivative contracts for the purchase and sale of natural gas that are subject to mark-to-market accounting. Changes in the fair value of derivative instruments recoverable or refundable to customers and therefore subject to ASC Topic 980, Regulated Operations , are recorded as regulatory assets or liabilities while changes in the fair value of derivative instruments not affected by rate regulation are reflected in earnings. As part of its asset optimization program, Washington Gas enters into derivative contracts related to the sale and purchase of natural gas at a future price with the primary objective of securing operating margins that Washington Gas expects to ultimately realize. The derivatives used under this program may cause significant period-to-period volatility in earnings for the portion of net profits retained for shareholders; however, this earnings volatility will not change the realized margins that Washington Gas expects to earn. In accordance with ASC Topic 815, all financially and physically settled contracts under our asset optimization program are reported on a net basis in the statements of income in “Utility cost of gas”. From time to time, Washington Gas also utilizes derivative instruments that are designed to minimize the risk of interest-rate volatility associated with planned issuances of long-term debt. Gains or losses associated with these derivative transactions are deferred as regulatory assets or liabilities and amortized to interest expense in accordance with regulatory accounting requirements. Refer to Note 14— Derivative and Weather-Related Instruments for further discussion of our derivative activities. Non-Utility Operations. WGL Energy Services enters into both physical and financial contracts for the purchase and sale 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;” therefore, they are not subject to the mark-to-market accounting requirements of ASC Topic 815. WGL Energy Services records these derivatives as revenues or expenses depending on the nature of the economically hedged item. 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. The financial contracts and the portion of the physical contracts that qualify as derivative instruments are subject to the mark-to-market accounting requirements and are recorded on the balance sheet at fair value and are reflected in earnings. WGL Midstream nets financial and physical contracts in "Operating Revenues-Non-utility". WGL may, from time to time, designate interest rate swaps used to manage the interest rate risk associated with future debt issuances, as cash flow hedges. Any gains or losses arising from the effective portion of cash flow hedges are recorded in other comprehensive income and are amortized using the effective interest rate method into earnings over the same period as the hedged interest payments are made. Gains or losses arising from the ineffective portion of cash flow hedges are recognized in earnings immediately. INCOME TAXES We recognize deferred income tax assets and liabilities for all temporary differences between the financial statement basis and the tax basis of assets and liabilities, including those that are currently excluded for ratemaking purposes of Washington Gas. Regulatory assets or liabilities, corresponding to such additional deferred income tax assets or liabilities, may be recorded to the extent recoverable from or payable to customers through the ratemaking process in future periods. Refer to Note 2— Regulated Operations for Washington Gas’ regulatory assets and liabilities associated with income taxes due from and to customers at September 30, 2016 and 2015 . Amounts applicable to income taxes due from and due to customers primarily represent differences between the book and tax basis of net utility plant in service. We amortize investment tax credits as reductions to income tax expense over the estimated service lives of the related properties. During the year ended September 30, 2016 , WGL and Washington Gas early adopted ASU 2015-17. This standard amends the requirements to separately classify deferred income tax liabilities and assets into current and noncurrent amounts on a classified balance sheet and requires all deferred income tax liabilities and assets to be offset by taxing jurisdiction and classified as noncurrent. WGL and Washington Gas are applying ASU 2015-17 retrospectively. As a result of the retrospective adoption, $ 32.8 million and $ 24.7 million for WGL and Washington Gas, respectively, were reclassified from "Current Assets-Deferred income taxes" to "Deferred Credits-Deferred income taxes" on WGL's and Washington Gas' September 30, 2015 balance sheets. Refer to Note 9— Income Taxes which provides detailed financial information related to our income taxes. STOCK-BASED COMPENSATION We account for stock-based compensation expense in accordance with ASC Topic 718, Compensation—Stock Compensation, which requires us to measure and recognize stock-based compensation expense in our financial statements based on the fair value at the date of grant for our equity-classified share-based awards, which include performance shares granted to certain employees and shares issued to directors. For liability-classified share-based awards, which include performance units, we recognize stock-based compensation expense based on their fair value at the end of each reporting period. For both equity-classified and liability-classified share-based awards, we estimate forfeitures over the requisite service period when recognizing compensation expense; these estimates are periodically adjusted to the extent to which actual forfeitures differ from such estimates. Refer to Note 11— Stock-Based Compensation for further discussion of the accounting for our stock-based compensation plans. ASSET RETIREMENT OBLIGATIONS Washington Gas accounts for its AROs in accordance with ASC Subtopic 410-20, Asset Retirement and Environmental Obligations—Asset Retirement Obligations. Our asset retirement obligations include the costs to cut, purge and cap Washington Gas' distribution and transmission system and plug storage wells upon their retirement. We also have asset retirement obligations associated with our distributed generation assets. These standards require recording the estimated retirement cost over the life of the related asset by depreciating the present value of the retirement obligation, measured at the time of the asset’s acquisition, and accreting the liability until it is settled. There are timing differences between the ARO-related accretion and depreciation amounts being recorded pursuant to GAAP and the recognition of depreciation expense for legal asset removal costs that we are currently recovering in rates. These timing differences are recorded as a reduction to “Regulatory liabilities—Accrued asset removal costs” in accordance with ASC Topic 980. We do not have any assets that are legally restricted related to the settlement of asset retirement obligations. WGL Holdings, Inc. Changes in Asset Retirement Obligations (In millions) September 30, 2016 2015 Asset retirement obligations at beginning of year $ 207.7 $ 181.2 Liabilities incurred in the period 12.1 8.4 Liabilities settled in the period (a) (16.9 ) (14.6 ) Accretion expense 7.4 7.8 Revisions in estimated cash flows (b) — 24.9 Asset retirement obligations at the end of the year (c) $ 210.3 $ 207.7 Washington Gas Light Company Changes in Asset Retirement Obligations (In millions) September 30, 2016 2015 Asset retirement obligations at beginning of year $ 205.9 $ 179.8 Liabilities incurred in the period 10.4 8.1 Liabilities settled in the period (a) (16.9 ) (14.6 ) Accretion expense 7.2 7.7 Revisions in estimated cash flows (b) — 24.9 Asset retirement obligations at the end of the year (c) $ 206.6 $ 205.9 (a) Fiscal year 2015 includes asset retirement obligations of $1.6 million related to the Springfield Operations Center that were reclassified to "Current Liabilities - Liabilities held for sale." The building was sold in 2016. (b) WGL revised its assumptions regarding the timing and amounts related to its obligation to cut, cap and purge pipeline. The revision is primarily driven by our accelerated pipeline replacement programs. (c) Includes short-term asset retirement obligations of $7.2 million and $7.0 million for fiscal year 2016 and 2015 , respectively. 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 9 — Income taxes, for further discussion of this standard. OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required date of adoption Effect on the financial statements or other significant matters ASU 2015-03 and ASU 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost and Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements The standard requires an entity to present debt issuance costs in the balance sheet as a direct deduction of the debt liability in a manner consistent with its accounting treatment of debt discounts. The standard requires retrospective application. The new guidance does not change the recognition and measurement guidance for debt issuance costs. October 1, 2016 Implementation of these standards will result in a reduction of other deferred assets and long-term debt in our Consolidated Balance Sheets. The carrying amounts that would be reclassifed at September 30, 2016 is $9.3 million. 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 This standard is not expected to have an impact to net income nor a material impact on the balance sheet. ASU 2016-17, Consolidation (Topic 810): Interests Held through Related Parties that are Under Common Control The standard modifies the guidance issued with ASU 2015-02 to amend the consolidation guidance on how a reporting entity, that is the single decision maker of a VIE, should treat indirect interests in the entity held through related parties that are under common control with the reporting entity, when determining whether it is the primary beneficiary of that VIE. October 1, 2016 ASU 2016-17 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Entities that have already adopted th

Regulated Operations

Regulated Operations	12 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Regulated Operations	REGULATED OPERATIONS Washington Gas accounts for its regulated operations in accordance with ASC Topic 980. This standard includes accounting principles for companies whose rates are determined by independent third party regulators. When setting rates, regulators may require us to record expense in different periods than may be appropriate for unregulated enterprises. When this occurs, Washington Gas defers the associated costs as assets (regulatory assets) on its balance sheet and records them as expenses on its income statement as it collects the revenues designed to recover these costs through customers’ rates. Further, regulators can also impose liabilities upon a company for gains previously realized or for amounts previously collected from customers for expenses expected to be incurred in the future (regulatory liabilities). When Washington Gas files a request with certain regulatory commissions to modify customers’ rates, it is permitted to charge customers new rates, subject to refund, until the regulatory commission renders a final decision on the amount of the authorized change in rates. During this interim period, Washington Gas records a provision for a rate refund regulatory liability based on the difference between the amount it collects in rates and the amount it expects to recover from a final regulatory decision. Similarly, Washington Gas periodically records provisions for rate refunds related to other transactions. Actual results for these regulatory contingencies are often difficult to predict and could differ significantly from the estimates reflected in the financial statements. Refer to Note 13— Commitments and Contingencies for further discussion of regulatory matters and related contingencies. At September 30, 2016 and 2015 , we recorded the following regulatory assets and liabilities on our balance sheets. These assets and liabilities will be recognized as revenues or expenses in future periods as they are reflected in customers’ rates. Regulatory Assets and Liabilities (In millions) Regulatory Assets Regulatory Liabilities September 30, 2016 2015 2016 2015 Current: Gas costs due from/to customers (a) $ 4.1 $ 1.7 $ 12.1 $ 22.6 Interruptible sharing (a) 0.9 3.3 0.6 2.6 Revenue normalization mechanisms for Maryland and Virginia (a) 6.6 — — 8.4 Plant recovery mechanisms 3.7 0.8 0.3 1.0 Total current $ 15.3 $ 5.8 $ 13.0 $ 34.6 Deferred: Accrued asset removal costs $ — $ — $ 310.8 $ 325.5 Deferred gas costs (a)(b) 179.9 190.7 — — Pension and other post-retirement benefits Other post-retirement benefit costs—trackers (c) — 0.1 — — Deferred pension costs—trackers (c) 29.8 38.0 — — ASC Topic 715 unrecognized costs/income (a)(d) Pensions 193.4 173.9 — — Other post-retirement benefits — — 113.9 104.4 Total pension and other post-retirement benefits 223.2 212.0 113.9 104.4 Other Income tax-related amounts due from/to customers (e) 33.6 31.7 3.6 4.2 Losses/gains on issuance and extinguishments of debt and interest-rate derivative instruments (a)(f) 17.5 11.1 1.5 1.6 Deferred gain on sale of assets (a) — — 1.0 1.4 Rights-of-way fees (a) 0.3 1.6 — — Business process outsourcing and related costs (a) 9.8 2.7 — — Non-retirement post-employment benefits (a)(g) 19.2 18.9 — — Deferred integrity management expenditures (a)(h) 8.5 5.1 — — Recoverable portion of abandoned LNG facility 4.3 5.0 — — Environmental response costs (a)(i) 1.3 1.8 — — Other regulatory expenses (a) 4.1 2.1 8.3 9.9 Total other $ 98.6 $ 80.0 $ 14.4 $ 17.1 Total deferred $ 501.7 $ 482.7 $ 439.1 $ 447.0 Total $ 517.0 $ 488.5 $ 452.1 $ 481.6 (a) Washington Gas does not earn its overall rate of return on these assets. Washington Gas is allowed to recover and required to pay, using short-term interest rates, the carrying costs related to billed gas costs due from and to its customers in the District of Columbia and Virginia jurisdictions. (b) Includes fair value of derivatives, which are not included in customer bills until settled. (c) Relates to the District of Columbia jurisdiction. (d) Refer to Note 10-Pension and Other Post-Retirement Benefit Plans for a further discussion of these amounts. (e) This balance represents amounts due from customers for deferred tax liabilities related to tax benefits on deduction flowed directly to customers prior to the adoption of income tax normalization for ratemaking purposes. (f) The losses or gains on the issuance and extinguishment of debt and interest-rate derivative instruments include unamortized balances from transactions executed in prior fiscal years. These transactions create gains and losses that are amortized over the remaining life of the debt as prescribed by regulatory accounting requirements. (g) Represents the timing difference between the recognition of workers compensation and short-term disability costs in accordance with generally accepted accounting principles and the way these costs are recovered through rates. (h) This balance represents amounts for deferred expenditures associated with Washington Gas’ Distribution Integrity Management Program (DIMP) in Virginia. (i) This balance represents allowed remediation expenditures at Washington Gas sites to be recovered through rates for Maryland and the District of Columbia. The recovery period is over several years. As required by ASC Topic 980, Washington Gas monitors its regulatory and competitive environment to determine whether the recovery of its regulatory assets remains probable. If Washington Gas were to determine that recovery of these assets is no longer probable, it would write off the assets against earnings. We have determined that ASC Topic 980 continues to apply to our regulated operations, and the recovery of our regulatory assets at September 30, 2016 is probable.

Accounts Payable and Other Accr

Accounts Payable and Other Accrued Liabilities	12 Months Ended
	Sep. 30, 2016
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable and Other Accrued Liabilities	ACCOUNTS PAYABLE AND OTHER ACCRUED LIABILITIES The tables below provide details for the amounts included in “Accounts payable and other accrued liabilities” on the balance sheets for both WGL and Washington Gas. WGL Holdings, Inc. September 30, (In millions) 2016 2015 Accounts payable—trade $ 353.0 $ 277.3 Employee benefits and payroll accruals 34.4 31.4 Other accrued liabilities 18.0 16.4 Total $ 405.4 $ 325.1 Washington Gas Light Company September 30, (In millions) 2016 2015 Accounts payable—trade $ 161.0 $ 122.2 Employee benefits and payroll accruals 32.2 29.5 Other accrued liabilities 11.8 7.6 Total $ 205.0 $ 159.3

Short-Term Debt

Short-Term Debt	12 Months Ended
	Sep. 30, 2016
Short-term Debt [Abstract]
Short-Term Debt	SHORT-TERM DEBT WGL and Washington Gas satisfy their short-term financing requirements through the sale of commercial paper, financing arrangements with third-party lenders, or through bank borrowings. Due to the seasonal nature of the regulated utility and retail energy-marketing segments, short-term financing requirements can vary significantly during the year. Revolving credit agreements are maintained to support outstanding commercial paper and to permit short-term borrowing flexibility. The policy of each WGL and Washington Gas is to maintain bank credit facilities in amounts equal to or greater than the expected maximum commercial paper position. The following is a summary of committed credit available at September 30, 2016 and 2015 . Committed Credit Available (In millions) September 30, 2016 WGL (b) Washington Gas Total Consolidated Committed credit agreements Unsecured revolving credit facility, expires December 19, 2019 (a) $ 450.0 $ 350.0 $ 800.0 Less: Commercial Paper (227.0 ) (42.0 ) (269.0 ) Net committed credit available $ 223.0 $ 308.0 $ 531.0 Weighted average interest rate 0.73 % 0.46 % 0.69 % September 30, 2015 Committed credit agreements Unsecured revolving credit facility, expires April 3, 2017 (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 September 30, 2016 and 2015 , there were no outstanding bank loans from WGL’s or Washington Gas’ revolving credit facilities. Under the terms of the credit agreements, the ratio of consolidated financial indebtedness to consolidated total capitalization may not exceed 0.65 to 1.0 ( 65.0% ). At September 30, 2016 , WGL's and Washington Gas' ratios of consolidated financial indebtedness to consolidated total capitalization were 56% and 48% , respectively. In addition, WGL and Washington Gas are required to inform lenders of changes in corporate existence, financial conditions, litigation and environmental warranties that might have a material adverse effect. Failure to inform the lenders’ agent of these material changes might constitute default under the agreements. Another potential default may be deemed to exist if WGL or Washington Gas were to fail to pay principal or interest when due on any other indebtedness. Such defaults, if not remedied, could lead to suspension of further loans and/or acceleration in which obligations become immediately due and payable. At September 30, 2016 , WGL and Washington Gas were in compliance with all of the covenants under their revolving credit facilities. PROJECT FINANCING Washington Gas obtains third-party project financing on behalf of the Federal government to provide funds during the construction of certain energy management services projects entered into under Washington Gas' area-wide contract. As the financing entity funds the energy management services project, Washington Gas establishes a payable to the financing entity. As work is performed, Washington Gas establishes a receivable representing the government's obligation to remit principal and interest. The payable and receivable are equal to each other at the end of the construction period, but there could be timing differences in the recognition of the project related payable and receivable during the construction period. When these projects are formally “accepted” by the government and deemed complete, Washington Gas assigns the ownership of the receivable to the financing entity in satisfaction of the obligation to the financing entity and removes both the receivable and the obligation related to the financing from its financial statements. As of September 30, 2016 , Washington Gas recorded a $73.3 million "Unbilled revenues" on the balance sheet and a $62.4 million corresponding short-term obligation to the lender in "Notes payable", for energy management services projects that were not complete. Because these projects are financed for government agencies which have minimal credit risk, and with which we have previous collection experience, Washington Gas did not record a corresponding reserve for bad debts related to these receivables at September 30, 2016 .

Long-Term Debt

Long-Term Debt	12 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Long-Term Debt	LONG-TERM DEBT FIRST MORTGAGE BONDS The Mortgage of Washington Gas dated January 1, 1933 (Mortgage), as supplemented and amended, securing any First Mortgage Bonds (FMBs) it issues, constitutes a direct lien on substantially all property and franchises owned by Washington Gas, other than a small amount of property that is expressly excluded. At September 30, 2016 and 2015 , Washington Gas had no debt outstanding under the Mortgage. Any FMBs that may be issued in the future will represent indebtedness of Washington Gas. SHELF REGISTRATION At September 30, 2016 WGL had the capacity under a shelf registration to issue an unspecified amount of long-term debt securities and Washington Gas had the capacity under shelf registration statement to issue up to $350.0 million of additional MTNs. UNSECURED NOTES WGL and Washington Gas issue long-term notes with individual terms regarding interest rates, maturities and call or put options. These notes can have maturity dates of one or more years from the date of issuance. The following tables show the outstanding notes as of September 30, 2016 and 2015 . Long-Term Debt Outstanding ($ In millions) WGL (a) Washington Gas Total Consolidated September 30, 2016 Long-term debt (b) $ 500.0 $ 946.0 $ 1,446.0 Unamortized discount (1.6 ) (0.1 ) (1.7 ) Total Long-Term Debt $ 498.4 $ 945.9 $ 1,444.3 Weighted average interest rate 2.50 % 5.12 % 4.21 % September 30, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 Unamortized discount (1.7 ) (0.1 ) (1.8 ) Less — Current maturities — 25.0 25.0 Total Long-Term Debt $ 248.3 $ 695.9 $ 994.2 Weighted average interest rate 3.66 % 5.58 % 5.08 % (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. ( b) Includes Senior Notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities. The indenture for the unsecured MTNs and the note purchase agreement for the private placement notes provide that Washington Gas will not issue any FMBs under its Mortgage without securing all MTNs and the subject private placement notes with the Mortgage. Certain of Washington Gas’ outstanding MTNs and private placement notes have a make-whole call feature that pays the holder a premium based on a spread over the yield to maturity of a U.S. Treasury security having a comparable maturity, when that particular note is called by Washington Gas before its stated maturity date. With the exception of this make-whole call feature, Washington Gas is not required to pay call premiums for calling debt prior to the stated maturity date. On February 18, 2016, WGL entered into a credit agreement providing for a term loan facility and borrowed $250 million under the agreement. The credit agreement provides for a maturity date of February 18, 2018, with a one year extension option with the lenders' approval. In addition to the initial borrowings, the credit agreement permits, with the lenders' approval, additional borrowings of up to $100 million , for maximum potential borrowings under the credit agreement of $350 million . The interest rate on loans made under the credit agreement will be a fluctuating rate that will be determined from time to time based on parameters set forth in the credit agreement. In addition, on September 16, 2016, Washington Gas issued an aggregate principle amount of $250 million , 3.796% medium-term notes due in 2046 . The notes are subject to prepayment at Washington Gas' option at any time in whole or from time to time in part, at a redemption price equal to the greater of (i) 100% of the principal amount thereof and (ii) the sum of the present values of the remaining scheduled payments of principal and interest thereon, plus a make-whole call premium, plus, in either such case, accrued and unpaid interest on the principal of such notes to the date of redemption. At any time on and after March 15, 2046, Washington Gas may redeem the notes on any date or dates, in whole or from time to time in part, at 100% of the principal of such notes, plus accrued and unpaid interest on the principal of such notes to the date of redemption. The following tables show long-term debt issuances and retirements for the years ended September 30, 2016 and 2015 . Long-Term Debt Issuances and Retirements ($ In millions) Principal (b) Interest Rate Effective Cost Nominal Maturity Date Year Ended September 30, 2016 WGL (a) Issuances: 2/18/2016 $ 250.0 1.34 % (c) 1.34 % (c) 2/18/2018 Total $ 250.0 Washington Gas Issuances: 9/16/2016 $ 250.0 3.80 % 4.01 % (d) 3/15/2046 Total 250.0 Total consolidated issuances $ 500.0 Washington Gas Retirements: 1/18/2016 $ 25.0 5.17 % n/a 1/18/2016 Total $ 25.0 Year Ended September 30, 2015 WGL (a) Issuances: 10/24/2014 $ 100.0 2.25 % 2.42 % 11/1/2019 10/24/2014 125.0 4.60 % 5.11 % 11/1/2044 12/16/2014 25.0 4.60 % 5.53 % 11/1/2044 Total $ 250.0 Washington Gas Issuances: 12/15/2014 $ 50.0 4.24 % 4.41 % 12/15/2044 Total 50.0 Total consolidated issuances $ 300.0 Washington Gas Retirements: 8/9/2015 $ 20.0 4.83 % n/a 8/9/2015 Total $ 20.0 (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. (b) Represents face amount. (c) Floating rate per annum that will be determined from time to time based on parameters set forth in the credit agreement. Effective cost reflects current rate. (d) The estimated effective cost of the issued notes, including consideration of issuance fees and hedge costs. LONG-TERM DEBT MATURITIES Maturities of long-term debt for each of the next five fiscal years and thereafter as of September 30, 2016 are summarized in the following table. Long-Term Debt Maturities (a) (In millions) WGL (b) Washington Gas Total 2017 $ — $ — $ — 2018 250.0 — 250.0 2019 — 50.0 50.0 2020 100.0 50.0 150.0 2021 — — — Thereafter 150.0 846.0 996.0 Total $ 500.0 $ 946.0 $ 1,446.0 Less: current maturities — — — Total non-current $ 500.0 $ 946.0 $ 1,446.0 (a) Excludes unamortized discounts of $ 1.6 million and $0.1 million at September 30, 2016 , for WGL and Washington Gas, respectively. (b) WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Common Stock

Common Stock	12 Months Ended
	Sep. 30, 2016
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock	COMMON STOCK — WGL COMMON STOCK OUTSTANDING Shares of common stock outstanding were 51,080,612 and 49,728,662 at September 30, 2016 and 2015 , respectively. COMMON STOCK RESERVES At September 30, 2016 , there were 8,252,975 authorized, but unissued, shares of common stock reserved under the following plans: Common Stock Reserves Reserve for: Number of Shares Omnibus incentive compensation plan (a) 2,790,712 Dividend reinvestment and common stock purchase plan 2,775,341 Employee savings plans 637,196 Directors’ stock compensation plan 68,694 ATM program 1,981,032 Total common stock reserves 8,252,975 (a) In March 2007, WGL adopted a shareholder-approved Omnibus Incentive Compensation Plan to replace on a prospective basis the 1999 Incentive Compensation Plan. In December 2015, the Board of Directors approved the 2016 Omnibus Incentive Compensation Plan that became effective upon shareholder approval at WGL's Annual Meeting of Stockholders on March 1, 2016. The plan was included as an exhibit to WGL's proxy statement under cover of Form 14A filed on January 20, 2016. Following shareholder approval of the 2016 Omnibus Incentive Compensation Plan, WGL will no longer make equity grants under the 2007 Omnibus Incentive Compensation Plan (but shares issued pursuant to outstanding grants under the 2007 plan will be issued pursuant to that plan). Refer to Note 11—Stock-Based Compensation for a discussion regarding our stock-based compensation plans. On November 24, 2015, WGL entered into an equity distribution agreement and filed a prospectus supplement relating to a continuous offering under which WGL may sell common stock with an aggregate sales price of up to $ 150 million through an at-the-market (ATM) program. Sales of common stock can be made by means of privately negotiated transactions, as transactions on the New York Stock Exchange at market prices or in such other transactions as agreed upon by WGL and the sales agents and in accordance with applicable securities laws. During the fiscal year ended September 30, 2016 , WGL has issued 1,162,305 shares of common stock under the ATM program for gross proceeds of $78.2 million .

Preferred Stock

Preferred Stock	12 Months Ended
	Sep. 30, 2016
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock	PREFERRED STOCK Washington Gas has three series of cumulative preferred stock outstanding, and each series is subject to redemption by Washington Gas. All three series have a dividend preference that prohibits Washington Gas from declaring and paying dividends on shares of its common stock unless dividends on all outstanding shares of the preferred stock have been fully paid for all past quarterly dividend periods. In addition, all outstanding shares of preferred stock have a preference as to the amounts that would be distributed in the event of a liquidation or dissolution of Washington Gas. The following table presents this information, as well as call prices for each preferred stock series outstanding. Preferred Stock Preferred Liquidation Preference Series Shares Per Share Call Price Outstanding Outstanding Involuntary Voluntary Per Share $4.80 150,000 $100 $101 $101 $4.25 70,600 $100 $105 $105 $5.00 60,000 $100 $102 $102

Earnings Per Share

Earnings Per Share	12 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic EPS of WGL is computed by dividing net income by the weighted average number of common shares outstanding during the reported period. Diluted EPS assumes the issuance of common shares pursuant to stock-based compensation plans at the beginning of the applicable period unless the effect of such issuance would be anti-dilutive (refer to Note 11 —Stock-Based Compensation ). For the fiscal year ended September 30, 2016 , there were no outstanding stock options and we had 86,500 weighted average performance shares issuable pursuant to our stock-based compensation plans that were excluded from the diluted share calculation due to the anti-dilutive effect of such shares. For fiscal years ended September 30, 2015 and September 30, 2014 , there were no anti-dilutive shares excluded from the calculation of diluted EPS. The following table reflects the computation of our basic and diluted EPS for the fiscal years ended September 30, 2016 , 2015 and 2014 . Basic and Diluted EPS Years Ended September 30, (In thousands, except per share data) 2016 2015 2014 Basic earnings per average common share: Net income applicable to common stock $ 167,594 $ 131,259 $ 105,940 Average common shares outstanding—basic 50,369 49,794 51,759 Basic earnings per average common share $ 3.33 $ 2.64 $ 2.05 Diluted earnings per average common share: Net income applicable to common stock $ 167,594 $ 131,259 $ 105,940 Average common shares outstanding—basic 50,369 49,794 51,759 Stock-based compensation plans 195 266 11 Total average common shares outstanding—diluted 50,564 50,060 51,770 Diluted earnings per average common share $ 3.31 $ 2.62 $ 2.05

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES 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 (IRS) for years ended prior to September 30, 2012 except for pending carryback refund claims. Substantially all state income tax years in major jurisdictions are closed for years ended prior to September 30, 2012. WGL and each of its subsidiaries participate in a tax sharing agreement that establishes the method for allocating tax benefits from losses that are utilized on the consolidated income tax return. The consolidated tax is apportioned among the subsidiaries on the separate return method and losses of the parent, WGL, are allocated to the subsidiaries that have taxable income. In fiscal year 2016 , Washington Gas shared $1.1 million of tax benefits from the tax sharing agreement that was reflected as a tax increase on Washington Gas' statements of income. During fiscal years 2015 and 2014 , Washington Gas realized $0.5 million and $2.9 million of tax savings as a result of this tax sharing agreement. The effect of this allocation of benefits to Washington Gas has no effect on our consolidated financial statements. State income tax returns are filed on a separate company basis in most states where we have operations and/or a requirement to file. On September 13, 2013, the U.S. Treasury Department issued final income tax regulations to address the costs incurred in acquiring, producing, or improving tangible property. The regulations are effective for WGL and Washington Gas for the tax year beginning October 1, 2014. WGL and Washington Gas filed Forms 3115 along with its income tax return for the year ended September 30, 2015 in June 2016. The financial impact of these regulations did not have a material impact on the financial statements. On October 1, 2015, WGL and Washington Gas early adopted ASU 2015-17. This standard amends the requirements to separately classify deferred income tax liabilities and assets into current and noncurrent amounts on a classified balance sheet, and requires all deferred income tax liabilities and assets to be offset by taxing jurisdiction and classified as noncurrent. WGL and Washington Gas applied ASU 2015-17 retrospectively. As a result of the retrospective adoption, $ 32.8 million and $ 24.7 million were reclassified from "Current Assets-Deferred income taxes" to "Deferred Credits-Deferred income taxes" on WGL's and Washington Gas' September 30, 2015 balance sheets, respectively. The tables below provide the following for WGL and Washington Gas: (i) the components of income tax expense; (ii) a reconciliation between the statutory federal income tax rate and the effective income tax rate and (iii) the components of accumulated deferred income tax assets and liabilities at September 30, 2016 and 2015 . WGL Holdings, Inc. Components of Income Tax Expense Years Ended September 30, (In thousands) 2016 2015 2014 INCOME TAX EXPENSE Current: Federal $ (57,690 ) $ (18,639 ) $ 29,976 State (1,983 ) 2,977 5,149 Total current (59,673 ) (15,662 ) 35,125 Deferred: Federal Accelerated depreciation 93,175 71,529 35,747 Other 49,638 17,726 (18,014 ) State Accelerated depreciation 12,993 13,739 9,822 Other 8,073 1,411 (1,760 ) Total deferred 163,879 104,405 25,795 Amortization of investment tax credits (6,132 ) (4,939 ) (3,666 ) Total income tax expense $ 98,074 $ 83,804 $ 57,254 WGL Holdings, Inc. Reconciliation Between the Statutory Federal Income Tax Rate and Effective Tax Rate Years Ended September 30, ($ In thousands) 2016 2015 2014 Income taxes at statutory federal income tax rate $ 93,253 35.00 % $ 75,760 35.00 % $ 57,580 35.00 % Increase (decrease) in income taxes resulting from: Accelerated depreciation less amount deferred 908 0.34 1,187 0.55 1,875 1.14 Amortization of investment tax credits (6,132 ) (2.30 ) (4,939 ) (2.28 ) (3,666 ) (2.23 ) Cost of removal (3,722 ) (1.40 ) (2,721 ) (1.26 ) (4,902 ) (2.98 ) State income taxes-net of federal benefit 12,969 4.87 11,109 5.13 8,734 5.31 Medicare Part D adjustment — — — — (3,621 ) (2.20 ) ASDHI impairment — — 1,969 0.91 — — Other items-net 798 0.30 1,439 0.66 1,254 0.76 Total income tax expense and effective tax rate $ 98,074 36.81 % $ 83,804 38.71 % $ 57,254 34.80 % WGL Holdings, Inc. Components of Accumulated Deferred Income Tax Assets (Liabilities) (In thousands) 2016 2015 Deferred income tax assets: Pensions $ 60,685 $ 44,468 Uncollectible accounts 12,441 10,389 Inventory overheads 5,046 5,873 Employee compensation and benefits 49,443 57,230 Derivatives 58,203 43,891 Deferred gas costs — 2,406 Solar grant/investment tax credit 64,149 53,067 Tax credit carry forward 118,980 55,040 Net operating loss 27,741 — Other (a) 1,075 5,640 Total assets 397,763 278,004 Deferred income tax liabilities: Other post-retirement benefits 69,899 54,860 Accelerated depreciation and other plant related items 949,807 794,099 Losses/gains on reacquired debt 1,155 1,292 Income taxes recoverable through future rates 71,352 68,245 Deferred gas costs 1,696 815 Partnership basis differences 27,532 29,468 Valuation allowances 2,188 2,188 Total liabilities 1,123,629 950,967 Net accumulated deferred income tax assets (liabilities) $ (725,866 ) $ (672,963 ) (a) Includes $ 0.897 million in deferred income tax assets reported in "Deferred charges and other assets" on the consolidated balance sheet. Washington Gas Light Company Components of Income Tax Expense Years Ended September 30, (In thousands) 2016 2015 2014 INCOME TAX EXPENSE Current: Federal $ (48,064 ) $ (5,305 ) $ 37,098 State (2,957 ) 907 4,262 Total current (51,021 ) (4,398 ) 41,360 Deferred: Federal Accelerated depreciation 93,385 71,046 34,833 Other 13,826 (6,619 ) (30,523 ) State Accelerated depreciation 13,081 13,701 9,540 Other 3,190 (1,507 ) (6,800 ) Total deferred 123,482 76,621 7,050 Amortization of investment tax credits (795 ) (832 ) (876 ) Total income tax expense $ 71,666 $ 71,391 $ 47,534 Washington Gas Light Company Reconciliation Between the Statutory Federal Income Tax Rate and Effective Tax Rate Years Ended September 30, ($ In thousands) 2016 2015 2014 Income taxes at statutory federal income tax rate $ 64,673 35.00 % $ 63,024 35.00 % $ 51,050 35.00 % Increase (decrease) in income taxes resulting from: Accelerated depreciation less amount deferred 1,936 1.05 2,108 1.17 1,875 1.29 Amortization of investment tax credits (795 ) (0.43 ) (832 ) (0.46 ) (876 ) (0.60 ) Cost of removal (3,722 ) (2.01 ) (2,721 ) (1.51 ) (4,902 ) (3.36 ) State income taxes-net of federal benefit 8,310 4.50 8,986 4.99 6,711 4.60 Consolidated tax sharing allocation 1,073 0.58 (533 ) (0.30 ) (2,862 ) (1.96 ) Medicare Part D adjustment — — — — (3,621 ) (2.48 ) Other items-net 191 0.10 1,359 0.76 159 0.09 Total income tax expense and effective tax rate $ 71,666 38.79 % $ 71,391 39.65 % $ 47,534 32.58 % Washington Gas Light Company Components of Accumulated Deferred Income Tax Assets (Liabilities) (In thousands) 2016 2015 Deferred income tax assets: Pensions $ 59,878 $ 43,748 Uncollectible accounts 8,054 7,637 Inventory overheads 5,046 5,873 Employee compensation and benefits 43,755 38,857 Derivatives 27,394 38,887 Deferred gas costs — 2,406 Net operating loss 24,588 — Other — 862 Total assets 168,715 138,270 Deferred income tax liabilities: Other post-retirement benefits 69,520 54,566 Accelerated depreciation and other plant related items 783,919 681,108 Losses/gains on reacquired debt 1,155 1,292 Income taxes recoverable through future rates 71,063 67,953 Deferred gas costs 1,696 815 Other 5,082 1,300 Total liabilities 932,435 807,034 Net accumulated deferred income tax assets (liabilities) $ (763,720 ) $ (668,764 ) In June 2016 , we filed our tax return for the year ended September 30, 2015 . The following table summarizes the change in unrecognized tax benefits during fiscal year 2016 , 2015 , 2014 and our total unrecognized tax benefits at September 30, under the provisions of ASC Topic 740, Income Taxes: Unrecognized Tax Benefits (In thousands) 2016 2015 2014 Total unrecognized tax benefits, October 1, $ 38,627 $ 32,613 $ 25,051 Increases in tax positions relating to current year 10,645 12,848 10,512 Decreases in tax positions relating to prior year (6,989 ) (6,834 ) (2,950 ) Total unrecognized tax benefits, September 30, $ 42,283 $ 38,627 $ 32,613 During the year, the unrecognized tax benefits for WGL and Washington Gas increased by approximately $3.7 million relating to uncertain tax positions, 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. The IRS completed its audit of the tax years related to the change in accounting method for repairs without proposing any changes, however, they could re-examine this issue in the future. WGL and Washington Gas recognize 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. During the fiscal year ended September 30, 2016 there was no change in accrued interest associated with uncertain tax positions. During the fiscal years ended September 30, 2015 and 2014 , interest expense on uncertain tax positions was minimal.

Pension and Other Post-Retireme

Pension and Other Post-Retirement Benefit Plans	12 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Pension and Other Post-Retirement Benefit Plans	PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS Washington Gas maintains a qualified, trusteed, non-contributory defined benefit pension plan (qualified pension plan) covering most active and vested former employees of Washington Gas and certain employees of WGL subsidiaries. The non-contributory defined benefit pension plan is closed to all employees hired on or after January 1, 2010 and instead employees are eligible to receive supplemental contributions to their defined-contribution savings plan. Washington Gas accounts for the qualified pension plan and other post-retirement benefit plans under the provisions of ASC 715, Compensation-Retirement Benefits. Several executive officers of Washington Gas also participate in a non-funded defined benefit supplemental executive retirement plan (DB SERP), a non-qualified pension plan. A rabbi trust has been established for the potential future funding of the DB SERP liability. The DB SERP was closed to new entrants beginning January 1, 2010 and instead, executive officers are eligible to participate in a non-funded defined contribution SERP (DC SERP). In addition, effective January 1, 2010, Washington Gas established a non-funded defined benefit restoration plan (DB restoration) for the purpose of providing supplemental pension and pension-related benefits to a select group of management employees. WGL subsidiaries offer defined-contribution savings plans to all eligible employees. These plans allow participants to defer on a pre-tax or after-tax basis, a portion of their salaries for investment in various alternatives. We make matching contributions to the amounts contributed by employees in accordance with the specific plan provisions. Total matching contributions to our savings plans were $5.1 million , $4.6 million and $4.2 million during fiscal years 2016 , 2015 and 2014 , respectively. All employees not earning benefits in the qualified pension plan receive an employer provided supplemental contribution ranging from 4% to 6% depending on years of service. Total supplemental contributions to the plan were $2.6 million , $2.1 million and $1.6 million during fiscal years ended September 30, 2016 , 2015 and 2014 , respectively. Washington Gas provides certain healthcare and life insurance benefits for retired employees of Washington Gas and certain employees of WGL subsidiaries. Substantially all employees of Washington Gas may become eligible for such benefits if they attain retirement status while working for Washington Gas. For eligible retirees and dependents not yet receiving Medicare benefits, Washington Gas provides medical, prescription drug and dental benefits through Preferred Provider Organization (PPO) or Health Maintenance Organization (HMO) plans. On April 24, 2014, Washington Gas replaced the existing retiree medical, prescription drug and dental benefit plan options for Medicare-eligible retirees age 65 and older with a special tax-free HRA plan effective January 1, 2015. With the introduction of the new plan, participating retirees and dependents will receive an annual subsidy to help purchase supplemental medical, prescription drug and dental coverage in the marketplace. As part of the new HRA plan, participants who enroll in a Medicare Part D prescription drug plan and meet the threshold for Medicare catastrophic prescription drug coverage will be eligible for an additional reimbursement of their out-of-pocket prescription drug costs in excess of the threshold. Retirees and dependents under age 65 will still be covered under the existing Washington Gas Light Company Retiree Medical Plan until they become eligible for Medicare at age 65 and can obtain coverage through the new HRA plan. Washington Gas accounts for these benefits under the provisions of ASC 715, Compensation-Retirement Benefits. On September 25, 2015, the Washington Gas Light Company Retiree Medical Plan was amended to limit the aggregate cost of applicable employer-sponsored coverage, thereby avoiding the 40% excise tax enacted by the Patient Protection and Affordable Care Act of 2010. The resolution, which is effective September 30, 2015 and applies to plan years beginning on or after January 1, 2018, includes a limit of $11,850 per participant, with a maximum limit of $30,950 for family coverage. This amendment resulted in a prior service credit of $26.1 million . Almost all costs associated with Washington Gas’ defined benefit post-retirement plans have historically been, and are expected to be, recovered through Washington Gas’ rates. Therefore, in accordance with ASC Topic 980 and ASC Topic 715, Washington Gas established a regulatory asset/liability for the substantial majority of the unrecognized costs/income associated with its defined benefit post-retirement plans. To the extent these amounts will not be recovered through Washington Gas’ rates, they are recorded directly to “Accumulated other comprehensive loss, net of taxes.” Obligations and Assets Washington Gas uses a measurement date of September 30 for its pension, and retiree healthcare and life insurance benefit plans. The following table provides certain information about Washington Gas’ post-retirement benefits: Post-Retirement Benefits Health and Life (In millions) Pension Benefits (a) Benefits Year Ended September 30, 2016 2015 2016 2015 Change in projected benefit obligation (b) Benefit obligation at beginning of year $ 947.5 $ 917.1 $ 299.9 $ 343.2 Service cost 14.2 15.5 4.6 7.1 Interest cost 41.3 39.1 13.1 14.7 Change in plan benefits 0.5 0.6 — (26.1 ) Actuarial loss (gain) 110.5 19.2 19.5 (23.7 ) Retiree contributions — — 2.3 2.0 Employer group waiver plan rebates — — 1.2 2.4 Benefits paid (44.7 ) (44.0 ) (16.3 ) (19.7 ) Projected benefit obligation at end of year (b) $ 1,069.3 $ 947.5 $ 324.3 $ 299.9 Change in plan assets Fair value of plan assets at beginning of year $ 780.2 $ 804.7 $ 438.5 $ 439.6 Actual return on plan assets 115.0 19.9 65.1 (0.3 ) Company contributions 1.8 1.8 14.9 16.0 Retiree contributions and employer group waiver plan rebates — — 3.5 3.6 Expenses (2.3 ) (2.2 ) (0.7 ) (0.7 ) Benefits paid (44.7 ) (44.0 ) (16.3 ) (19.7 ) Fair value of plan assets at end of year $ 850.0 $ 780.2 $ 505.0 $ 438.5 Funded status at end of year $ (219.3 ) $ (167.3 ) $ 180.7 $ 138.6 Total amounts recognized on balance sheet Non-current asset $ — $ — $ 180.7 $ 138.6 Current liability (6.3 ) (4.8 ) — — Non-current liability (213.0 ) (162.5 ) — — Total recognized $ (219.3 ) $ (167.3 ) $ 180.7 $ 138.6 (a) The DB SERP and DB Restoration, included in pension benefits in the table above, have no assets. (b) For the Health and Life Benefits, the change in projected benefit obligation represents the accumulated benefit obligation. The following table provides the projected benefit obligation (PBO) and accumulated benefit (ABO) for the qualified pension plan, DB SERP and DB Restoration at September 30, 2016 and 2015 . Projected and accumulated benefit obligation (In millions) Qualified Pension Plan DB SERP DB Restoration September 30, 2016 2015 2016 2015 2016 2015 Projected benefit obligation $ 1,005.0 $ 892.2 $ 60.4 $ 53.0 $ 3.9 $ 2.3 Accumulated benefit obligation $ 922.3 $ 822.8 $ 56.5 $ 48.7 $ 2.3 $ 1.2 AMOUNTS RECOGNIZED IN REGULATORY ASSETS/LIABILITIES AND ACCUMULATED OTHER COMPREHENSIVE INCOME The following table provides amounts recorded to regulatory assets, regulatory liabilities and accumulated other comprehensive loss/(income) at September 30, 2016 and 2015 : Unrecognized Costs/Income Recorded on the Balance Sheet (In millions) Pension Benefits Health and Life Benefits September 30, 2016 2015 2016 2015 Actuarial net loss $ 211.9 $ 190.1 $ 18.1 $ 43.8 Prior service cost (credit) 1.5 1.5 (142.5 ) (160.2 ) Total $ 213.4 $ 191.6 $ (124.4 ) $ (116.4 ) Regulatory asset (liability) (a) $ 193.4 $ 173.9 $ (118.0 ) $ (110.5 ) Pre-tax accumulated other comprehensive loss (gain) (b) 20.0 17.7 (6.4 ) (5.9 ) Total $ 213.4 $ 191.6 $ (124.4 ) $ (116.4 ) (a) The regulatory liability recorded on our balance sheets at September 30, 2016 and 2015 is net of a deferred income tax benefit of $ 4.1 million and $6.1 million , respectively. (b) The total amount of accumulated other comprehensive loss recorded on our balance sheets at September 30, 2016 and 2015 is net of an income tax benefit of $5.8 million and $5.1 million , respectively. The following table provides amounts that are included in regulatory assets/liabilities and accumulated other comprehensive loss associated with our unrecognized pension and other post-retirement benefit costs that were recognized as components of net periodic benefit cost during fiscal year 2016 . Amounts Recognized During Fiscal Year 2016 Regulatory assets/liabilities Accumulated other comprehensive loss (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Actuarial net loss (income) $ 15.3 $ 1.2 $ 1.5 $ 0.1 Prior service cost (credit) 0.2 (16.8 ) 0.1 (0.9 ) Total $ 15.5 $ (15.6 ) $ 1.6 $ (0.8 ) The following table provides amounts that are included in regulatory assets/liabilities and accumulated other comprehensive loss associated with our unrecognized pension and other post-retirement benefit costs that are expected to be recognized as components of net periodic benefit cost during fiscal year 2017 . Amounts to be Recognized During Fiscal Year 2017 Regulatory assets/liabilities Accumulated other comprehensive loss (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Actuarial net loss $ 19.9 $ 0.7 $ 2.1 $ — Prior service cost (credit) 0.2 (16.7 ) 0.1 (0.9 ) Total $ 20.1 $ (16.0 ) $ 2.2 $ (0.9 ) Realized and unrealized gains and losses for assets under Washington Gas’ post-retirement benefit plans are spread over a period of five years. Each year, 20% of the prior five years’ asset gains and losses are recognized. The market-related value of assets is equal to the market value of assets less the following percentages of prior years’ realized and unrealized gains and losses on equities: 80% of the prior year, 60% of the second prior year, 40% of the third prior year and 20% of the fourth prior year. Net Periodic Benefit Cost The components of the net periodic benefit costs (income) for fiscal years ended September 30, 2016 , 2015 and 2014 related to pension and other post-retirement benefits were as follows: Components of Net Periodic Benefit Costs (Income) (In millions) Pension Benefits Health and Life Benefits Year Ended September 30, 2016 2015 2014 2016 2015 2014 Service cost $ 14.2 $ 15.5 $ 14.0 $ 4.6 $ 7.1 $ 7.6 Interest cost 41.3 39.1 40.4 13.1 14.7 18.7 Expected return on plan assets (40.9 ) (44.6 ) (41.0 ) (20.4 ) (20.8 ) (19.3 ) Recognized prior service cost (credit) 0.3 0.3 0.3 (17.7 ) (15.3 ) (9.6 ) Recognized actuarial loss 16.9 18.7 16.8 1.2 4.4 5.0 Net periodic benefit cost 31.8 29.0 30.5 (19.2 ) (9.9 ) 2.4 Amount allocated to construction projects (5.6 ) (4.6 ) (4.3 ) 4.1 1.9 (0.4 ) Amount deferred as regulatory asset (liability)-net 7.1 7.1 7.0 (0.2 ) (0.2 ) (2.3 ) Amount charged (credited) to expense $ 33.3 $ 31.5 $ 33.2 $ (15.3 ) $ (8.2 ) $ (0.3 ) 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. ASSUMPTIONS The weighted average assumptions used to determine net periodic benefit obligations and net periodic benefit costs were as follows: Benefit Obligations Assumptions Pension Benefits Health and Life Benefits September 30, 2016 2015 2016 2015 Discount rate (a) 3.40%-3.70% 4.10%-4.50% 3.70 % 4.50 % Rate of compensation increase 3.50%-4.10% 3.50%-4.10% 4.10 % 4.10 % (a) The decrease in the discount rate in fiscal year 2016 compared to prior years primarily reflects the decrease in long-term interest rates. Net Periodic Benefit Cost Assumptions Pension Benefits Health and Life Benefits Years Ended September 30, 2016 2015 2014 2016 2015 2014 Discount rate (a) 4.10%-4.50% 4.00%-4.40% 4.50%-5.00% 4.50 % 4.40 % 4.60%-5.10% Expected long-term return on plan assets (b) 6.00 % 6.75 % 6.50 % 5.75 % 6.25 % 6.25 % Rate of compensation increase (c) 3.50%-4.10% 3.50%-4.10% 3.85%-5.15% 4.10 % 4.10 % 3.85 % (a) The changes in the discount rates over the last three fiscal years primarily reflect the changes in long-term interest rates. (b) For health and life benefits, the expected returns for certain funds may be lower due to certain portions of income that are subject to an assumed income tax rate of 45.3% . (c) The changes in the rate of compensation reflects the best estimates of actual future compensation levels including consideration of general price levels, productivity, seniority, promotion, and other factors such as inflation rates. Discount Rate Washington Gas determine the discount rate based on a portfolio of high quality fixed-income investments (AA- as assigned by Standard & Poor’s or Aa3 as assigned by Moody’s or better) whose cash flows would cover our expected benefit payments. Expected long-term return on plan assets Washington Gas determines the expected long-term rate of return on plan assets by averaging the expected earnings for the target asset portfolio. In developing the expected rate of return assumption, Washington Gas evaluates an analysis of historical actual performance and long-term return projections, which gives consideration to our asset mix and anticipated length of obligation of our plan. Mortality Assumptions In fiscal year 2015 Washington Gas adopted new mortality assumptions for its pension and other post-retirement benefit obligations, which reflect increased life expectancies in the U.S. The adoption of new mortality assumptions increased the projected benefit obligations for Washington Gas' pension and other post-retirement benefit by $46.8 million and $15.3 million , respectively. At September 30, 2016 there was no change to the mortality assumptions. Healthcare cost trend Washington Gas assumed the healthcare cost trend rates related to the accumulated post-retirement benefit obligation as of September 30, 2016, for non-Medicare eligible retirees, to be 6.3% for fiscal year 2017. Washington Gas expects the trend rate to decrease to 3.2% in fiscal year 2018 and 2.2% in fiscal year 2019, and remain at that level thereafter. The healthcare cost trend rate used to measure the accumulated post-retirement benefit obligation for non-Medicare eligible retirees as of September 30, 2015 was 6.7% for fiscal year 2016 . This rate was expected to decrease to 6.3% in fiscal year 2017, 3.2% in fiscal year 2018 and to 2.2% in fiscal year 2019, and remain at that level thereafter. Healthcare Trend (In millions) One Percentage-Point Increase One Percentage-Point Decrease Increase (decrease) total service and interest cost components $ 0.6 $ (0.5 ) Increase (decrease) post-retirement benefit obligation $ 5.9 $ (5.3 ) For Medicare eligible retirees age 65 and older that will receive a subsidy each year as a benefit from the HRA plan, Washington Gas assumed no increase to the annual subsidy in fiscal years 2016 and 2017 and a 3.0% increase thereafter in order to approximate possible future increases to the stipend. While the plan terms do not guarantee increases to the stipend, Washington Gas intends to review the stipend annually. INVESTMENT POLICIES AND STRATEGIES The investment objective of the qualified pension, healthcare, and life insurance benefit plans (“Plan” or “Plans”) is to allocate each Plan’s assets to appropriate investment asset classes (asset categories) so that the benefit obligations of each Plan are adequately funded, consistent with appropriate risk tolerance guidelines for the Plans’ and Washington Gas’ tolerance for risk. Washington Gas' portion of retired employee healthcare and life insurance benefits obligation is funded through two trusts: (i) the Washington Gas Light Company Post-retirement Benefit Master Trust for Retired Previously Union-Eligible Employees ("union-eligible trust") and (ii) the Washington Gas Light Company Post-retirement Benefit Master Trust for Retired Management Employees ("management trust"). In order to best achieve the investment objectives for each Plan, strategic allocation targets and ranges are established that control exposure to selected investment asset classes. Target qualified pension plan trust asset allocations are 32.5% U.S. Large-Cap Equities, 4.5% U.S. Small/Mid-Cap Equities, 8% International Equities, 5% Real Estate and 50% Fixed Income. Target asset allocations are 50% U.S. Large-Cap Equities and 50% Fixed Income for the union-eligible trust. Target asset allocations are 60% U.S. Large-Cap Equities and 40% Fixed Income for the management trust. Actual asset balances are reviewed monthly and are allowed to range within plus or minus 5% or less of the target allocations. Assets are generally rebalanced to target allocations before actual amounts fall below or rise above the allowable ranges. Asset/liability modeling (ALM) is used to test the benefits and risks of several potential strategic asset allocation mixes. Simulated investment performance results based on assumptions about expected return, volatility, and correlation characteristics of the selected asset classes are tested for their effects on contributions, pension expense, PBO funded status, and downside Value at Risk metrics over a ten-year planning time horizon. Important outcomes from past ALM studies include decisions to increase fixed income exposure, lengthen the duration of those fixed income assets and implement a dynamic asset allocation strategy that allows for the de-risking of the portfolio over time. Under this strategy, the target fixed income allocation percentage will increase by 5% for each 5% improvement in the plan’s funded ratio, as measured by an investment consultant. This strategy resulted in portfolio de-risking during October 2012 including increased fixed income exposure and reduced U.S. large-cap equity exposure. The most recent pension plan ALM study was completed during November 2014. The study did not result in any changes to investment strategy. For the qualified pension plan, Washington Gas’ funding policy is to contribute an amount sufficient to satisfy the minimum annual funding requirements under the Pension Protection Act. Any contributions above the minimum annual funding requirements would be limited to amounts that are deductible under appropriate tax law. For the healthcare and life insurance benefit plans, Washington Gas’ funding policy is to contribute amounts that are collected from ratepayers. Significant amounts of the various Plans’ assets are managed by the same financial institution. In addition, the Plans have a high exposure to U.S. based investments. There are no other significant risk concentrations related to investments in any entity, industry, country, commodity, or investment fund. Investment vehicles used to manage qualified pension plan trust and management trust assets include commingled funds and separately managed portfolios. A publicly offerable mutual fund is also employed to manage a portion of qualified pension plan trust assets. Commingled funds are used in the management of union-eligible trust assets. U.S. and international equity assets are diversified across sectors, industries, and investment styles. Fixed income assets are primarily diversified across U.S. government and investment grade corporate debt instruments, with some exposure to foreign sovereign debt and minor exposure to non-investment-grade securities. Real estate is diversified geographically across the U.S. by property type. The qualified pension plan’s investment policy allows the use of futures, options, and other derivatives for purposes of reducing portfolio risk and as a low-cost option for gaining market exposure, but derivatives may not be used for leverage. The qualified pension plan’s investment policy prohibits investments in Washington Gas securities. The prohibition applies to separately managed portfolios but does not apply to any commingled fund investments. The following tables present the fair value of the pension plan assets and health and life insurance plan assets by asset category as of September 30, 2016 and 2015 : Pension Plan Assets % of ($ In millions) Level 1 Level 2 Level 3 Total Total At September 30, 2016 Cash and cash equivalents $ 0.3 $ — $ — $ 0.3 — % Equity securities U.S. Small Cap 36.5 — — 36.5 4.3 Preferred Securities — 1.1 — 1.1 0.1 Fixed income securities U.S. Treasuries — 135.4 — 135.4 15.9 U.S. Corporate Debt — 200.6 — 200.6 23.6 U.S. Agency Obligations and Government Sponsored Entities — 18.2 — 18.2 2.1 Asset-Backed Securities — 1.5 — 1.5 0.3 Municipalities — 13.7 — 13.7 1.6 Non-U.S. Corporate Debt — 45.5 — 45.5 5.4 Other (a) — 6.8 — 6.8 0.8 Mutual Funds (b) 34.0 — — 34.0 4.0 Commingled Funds and Pooled Separate Accounts (c) — 302.3 22.4 324.7 38.2 Private Equity/Limited Partnerships (d) — 31.8 — 31.8 3.7 Derivatives (e) — 1.2 — 1.2 0.2 Total fair value of plan investments $ 70.8 $ 758.1 $ 22.4 $ 851.3 100.2 % Net payable (f) (1.3 ) (0.2 ) Total plan assets at fair value $ 850.0 100.0 % Pension Plan Assets % of ($ In millions) Level 1 Level 2 Level 3 Total Total At September 30, 2015 Cash and cash equivalents $ 0.8 $ — $ — $ 0.8 0.1 % Equity securities U.S. Small Cap 28.7 — — 28.7 3.7 Preferred Securities — 0.1 — 0.1 — Fixed income securities U.S. Treasuries — 101.3 — 101.3 13.0 U.S. Corporate Debt — 204.6 — 204.6 26.2 U.S. Agency Obligations and Government Sponsored Entities — 23.9 — 23.9 3.1 Asset-Backed Securities and Collateralized Mortgage Obligations — 1.7 — 1.7 0.2 Municipalities — 14.0 — 14.0 1.8 Non-U.S. Corporate Debt — 37.1 — 37.1 4.8 Repurchase Agreements (g) — 5.3 — 5.3 0.7 Other (a) — 4.7 — 4.7 0.6 Mutual Funds (b) — 29.3 — 29.3 3.7 Commingled Funds and Pooled Separate Accounts (c) — 274.8 27.7 302.5 38.7 Private Equity/Limited Partnerships (d) — 28.0 — 28.0 3.6 Derivatives (e) — (0.1 ) — (0.1 ) — Total fair value of plan investments $ 29.5 $ 724.7 $ 27.7 $ 781.9 100.2 % Net payable (f) (1.7 ) (0.2 ) Total plan assets at fair value $ 780.2 100.0 % (a) This category primarily includes non-U.S. government bonds as of September 30, 2016 and Yankee bonds and non-U.S. government bonds as of September 30, 2015. (b) At September 30, 2016 and September 30, 2015 the investment in a mutual fund consisted primarily of common stock of non-U.S. based companies. (c) At September 30, 2016, investments in commingled funds and a pooled separate account consisted primarily of 85% common stock of large-cap U.S companies; 14% income producing properties located in the United States; and 1% short-term money market investments. As of September 30, 2015, investments in commingled funds and a pooled separate accounts consisted primarily of 80% common stock of large-cap U.S companies; 18% income producing properties located in the United States; and 2% short-term money market investments. (d) At September 30, 2016 and 2015, an investments in a private equity/limited partnership consisted of common stock of international companies. (e) At September 30, 2016 and 2015, this category included a combination of long-term U.S. Treasury interest rate future contracts, currency forwards, a currency option interest rate swaps, and put and call options on both interest rate swaps and credit default swap index products. (f) At September 30, 2016 and September 30, 2015 this net payable primarily represents pending trades for investments purchased net of pending trades for investments sold and interest receivable. (g) This category includes Treasury Bills with a pre-commitment from the counterparty to repurchase the same securities on the next business day at an agreed-upon price. Healthcare and Life Insurance Plan Assets % of ($ In millions) Level 1 Level 2 Level 3 Total Total At September 30, 2016 Cash and Cash Equivalents $ 2.2 $ — $ — $ 2.2 0.4 % Fixed Income Securities U.S Agency Obligations — 1.7 — 1.7 0.3 U.S. Treasuries — 33.3 — 33.3 6.6 U.S. Corporate Debt — 38.2 — 38.2 7.6 Municipalities — 4.1 — 4.1 0.8 Non-U.S. Corporate Debt — 6.4 — 6.4 1.3 Other (a) — 2.8 — 2.8 0.6 Commingled Funds (b) — 415.6 — 415.6 82.3 Total fair value of plan investments $ 2.2 $ 502.1 $ — $ 504.3 99.9 % Net receivable (d) 0.7 0.1 Total plan assets at fair value $ 505.0 100.0 % At September 30, 2015 Cash and Cash Equivalents $ — $ — $ — $ — — % Mutual Funds (c) 1.9 — — 1.9 0.4 Fixed Income Securities U.S Agency Obligations — 1.8 — 1.8 0.4 U.S. Treasuries — 27.7 — 27.7 6.3 U.S. Corporate Debt — 33.5 — 33.5 7.7 Municipalities — 4.0 — 4.0 0.9 Non-U.S. Corporate Debt — 4.9 — 4.9 1.1 Other (a) — 4.3 — 4.3 1.0 Commingled Funds (b) — 359.7 — 359.7 82.0 Total fair value of plan investments $ 1.9 $ 435.9 $ — $ 437.8 99.8 % Net receivable (d) 0.7 0.2 Total plan assets at fair value $ 438.5 100.0 % (a) At September 30, 2016, this category consisted primarily of non-U.S government bonds. At September 30, 2015, this category consisted primarily of non-U.S. government bonds and Yankee bonds. (b) At September 30, 2016, investments held by commingled funds in which the plan invests consisted primarily of 68% of common stock of large-cap U.S. companies, 12% of U.S. Government fixed income securities and 20% of corporate bonds. At September 30, 2015, investments held by commingled funds in which the plan invests consisted primarily of 68% of common stock of large-cap U.S. companies, 16% of U.S. Government fixed income securities and 16% of corporate bonds. (c) At September 30, 2015, investment in mutual funds consisted of a short-term money market fund valued at $1.00 per share. (d) At September 30, 2016 and September 30, 2015 this net receivable primarily represents pending trades for investments sole and interest receivable net of pending trades for investments purchased. Valuation Methods Equity securities are traded on a securities exchange and are valued at the closing quoted market price as of the balance sheet date. Mutual funds are valued at the quoted net asset value (NAV) per share, which is computed as of the close of business on the balance sheet date. Mutual funds with a publicly quoted NAV per share are classified as Level 1; mutual funds with a NAV per share that is not made publicly available are classified as Level 2. A pooled separate account which has redemption restrictions is classified as Level 3. Commingled funds and pooled separate accounts are valued at the quoted NAV per unit, computed as of the close of business on the balance sheet date. The Private Equity/Limited Partnership funds is valued at the quoted NAV, which is computed monthly and allocated based on ownership interest in partners’ capital. Fixed income securities are valued using pricing models that consider various observable inputs such as benchmark yields, reported trades, broker quotes and issuer spreads to determine fair value. The Plans may engage in repurchase transactions. Generally, in accordance with the terms of a repurchase agreement, the Plans take possession of Treasury Bills in exchange for cash and the counterparty is obligated to repurchase, and the Plan to resell, the same securities at an agreed-upon price and time. The repurchase agreements have a one-day maturity and a fair value equal to the Plan’s cash outlay at the time the agreement is executed. The following table summarizes the changes in the fair value of the Level 3 assets for the fiscal years ended 2016 and 2015 : (In millions) Years Ended September 30, 2016 2015 Balance, beginning of year $ 27.7 $ 23.8 Actual return on plan assets: Assets still held at year end 0.2 3.9 Assets sold during the year 1.9 — Purchase, sales and settlements $ (7.4 ) $ — Balance, end of year $ 22.4 $ 27.7 Benefit Contribution During fiscal year 2016 , Washington Gas did not contribute to its qualified pension but did contribute $1.8 million to its non-funded DB SERP plan. During fiscal year 2017 , Washington Gas does not expect to make a contribution to its qualified pension plan and expects to make a payment of $6.3 million to its non-funded DB SERP. During fiscal year 2016 , Washington Gas contributed $14.9 million to its health and life insurance benefit plans. Washington Gas expects to make a contribution of $8.3 million to its health and life insurance benefit plans during fiscal year 2017 . Expected Benefit Payments Expected benefit payments, including benefits attributable to estimated future employee service, which are expected to be paid over the next ten years are as follows: Expected Benefit Payments (In millions) Pension Benefits Health and Life Benefits 2017 $ 51.8 $ 17.0 2018 52.6 16.5 2019 54.2 16.8 2020 55.3 16.8 2021 58.1 16.8 2022—2026 287.6 84.1 MEDICARE SUBSIDY RECEIPTS / EMPLOYER GROUP WAIVER PLAN Prior to 2013 Washington Gas sponsored a post-65 retiree prescription drug plan that was at least actuarially equivalent to Medicare (Medicare Part D), and as a result was eligible to receive a federal subsidy under the Medicare Prescription Drug, Improvement and Modernization Act of 2003. Effective January 1, 2013 Washington Gas implemented an Employer Group Waiver Plan with a wraparound supplemental plan (“EGWP/wrap”). Accordingly, the Washington Gas retiree medical plan began receiving direct reimbursements and discounts from Medicare and the large pharmaceutical companies. During the year ended September 30, 2015 , Washington Gas received $0.8 million in reimbursements related to the EGWP/wrap, respectively. Effective January 1, 2015, Washington Gas ceased to participate in the EGWP/wrap because participants age 65 and older transitioned into the new WGL Retiree HRA Plan, where such participants will receive an annual stipend that could be used to purchase health and prescription drug insurance. REGULATORY MATTERS A significant portion of the estimated pension and post-retirement medical and life insurance benefits apply to our regulated activities. Each regulatory commission having jurisdiction over Washington Gas requires it to fund amounts reflected in rates for post-retirement medical and life insurance benefits into irrevocable trusts. District of Columbia Jurisdiction The PSC of DC has approved a level of rates sufficient to recover annual costs associated with the qualified pension and other post-retirement benefits. Expenses of the SERP allocable to the District of Columbia are not recovered through rates. The PSC of DC granted the recovery of post-retirement medical and life insurance benefit costs determined in accordance with GAAP through a five-year phase-in plan that ended September 30, 1998. Washington Gas deferred the difference generated during the phase-in period as a regulatory asset. Effective October 1, 1998, the PSC of DC granted Washington Gas full recovery of costs determined under GAAP, plus a fifteen-year amortization of the regulatory asset established during the phase-in period that ended in fiscal year 2014. On May 15, 2013, the PSC of DC issued an order providing for recovery of unrecovered costs for pension and other post-retirement benefits as of November 30, 2012. The order allowed a five-year amortization period. Maryland Jurisdiction In Washington Gas’ most recent rate case, the PSC of MD approved 50% of the expenses of the SERP for recovery through rates. The PSC of MD has approved a level of rates sufficient to recover pension and other post-retirement benefit costs as determined under GAAP. Virginia Jurisdiction On September 28, 1995, the SCC of VA issued a generic order that allowed Washington Gas to recover most costs determined under GAAP for post-retirement medical and life insurance benefits in rates over twenty years. The SCC of VA, however, set a forty-year recovery period of the transition obligation. As prescribed by GAAP, Washington Gas amortizes these costs over a twenty-year period. With the exception of the transition obligation, the SCC of VA has approved a level of rates sufficient to recover annual costs for all pension and other post-retirement medical and life insurance benefit costs determined under GAAP.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION STOCK-BASED COMPENSATION FOR KEY EMPLOYEES We have stock-based awards outstanding in the form of performance shares and performance units. In March 2016, WGL adopted a shareholder-approved Omnibus Plan (2016 Plan) to replace, on a prospective basis, the Omnibus Incentive Plan (2007 Plan). Stock options, stock appreciation rights, restricted stock, deferred stock as a bonus or awards in lieu of obligations, dividend equivalents, other stock-based awards and cash awards may be granted under the 2016 Plan. The 2016 Plan allows WGL to issue up to 2,197,546 shares of common stock, subject to adjustment as provided by the plan, to persons including officers and key employees, designated by the Human Resources Committee of the Board of Directors. Refer to Note 6— Common Stock —W GL for amounts remaining to be issued under these plans. In March 2007, WGL adopted a shareholder-approved 2007 Plan to replace, on a prospective basis, its then-existing plan. Stock options, stock appreciation rights, restricted stock, deferred stock and stock as a bonus in lieu of other awards, dividend equivalents, other stock-based awards and cash awards may be granted under the 2007 Plan. The 2007 Plan allowed WGL to issue up to 1,700,000 shares of common stock, subject to adjustment as provided by the plan, to persons including officers and key employees, designated by the Human Resources Committee of the Board of Directors During the fiscal year ended September 30, 2016 , we granted performance shares and performance units under the 2007 Plan. We have not issued stock options under either the 2007 Plan or the 2016 Plan. For the fiscal years ended September 30, 2016 , 2015 and 2014 , we recognized stock-based compensation expense of $11.5 million , $15.5 million and $3.4 million , and related income tax benefits of $4.6 million , $6.2 million and $1.3 million , respectively. As of September 30, 2016 , total unrecognized compensation expense related to stock-based awards granted was $11.7 million . Performance shares and performance units comprised $5.1 million and $6.6 million of total unrecognized compensation expense, respectively. The total unrecognized compensation expense is expected to be recognized over a weighted average cost period of 1.7 years for performance shares and performance units. Description of Awards Performance shares earned pursuant to the terms of the grant are settled in an equivalent number of shares of WGL common stock and, for grants made in fiscal year 2016, dividend equivalents paid in cash. Performance units earned pursuant to terms of the grant are paid in cash and are valued at $1.00 per performance unit. Performance units and performance shares provide for accelerated vesting upon a change in control of WGL under certain circumstances. We generally issue new shares of common stock to provide for redemption of performance shares; however, we may, from time to time, repurchase shares of our common stock on the open market in order to meet these requirements. Performance shares are accounted for as equity awards, and performance units are accounted for as liability awards as they are settled in cash. During fiscal 2016 the Company granted performance shares and performance units that vest three years from the grant date based on the satisfaction of certain market or performance conditions. For half of the performance shares and half of the performance units granted in fiscal year 2016, the actual award that vests will vary from zero to 200 percent of the target award based on the Company's total shareholder return relative to a selected peer group of companies, which is a market condition under ASC Topic 718. The remaining half of the performance shares granted in fiscal year 2016 vest if our non-GAAP operating earnings per share on a diluted basis exceed dividends paid per share of common stock during the performance period, which is a performance condition under ASC Topic 718. For the remaining half of the performance units granted in fiscal year 2016 the actual award that vests will vary from zero to 200 percent of the target award based on our return on equity ratio achieved during the performance period, which is a performance condition under ASC Topic 718. Prior to fiscal 2016 the Company granted performance shares and performance units that vest three years from the grant date based on the satisfaction of a market condition. The actual performance shares and performance units that vest will vary from zero to 200 percent of the target award based on the Company's total shareholder return relative to a selected peer group of companies, which is a market condition under ASC Topic 718. Performance Shares The following table summarizes information regarding performance share activity during the fiscal year ended September 30, 2016 . Performance Share Activity Year Ended September 30, 2016 Number of Shares (a) Weighted Average Grant- Date Fair Value Non-vested and outstanding, beginning of year 304,089 $ 44.49 Granted 89,328 62.49 Vested (95,871 ) 43.29 Cancelled/forfeited (5,367 ) 50.63 Non-vested and outstanding, end of year 292,179 $ 50.28 (a) The number of common shares issued related to 248,394 non-vested performance shares outstanding at year-end may range from zero to 200 percent of this number based on our satisfaction of the market condition for total shareholder return relative to a selected peer group of companies. For 43,785 non-vested performance shares outstanding at year-end, the number of common shares issued may range from zero to 100% of this number based on our satisfaction of the performance condition for non-GAAP diluted earnings per share as compared to dividends paid per share. The total fair value of the performance shares outstanding at September 30, 2016 for the shares expected to vest in the future was $14.2 million . The total intrinsic value of performance shares vested during the year ended September 30, 2016 was $ 9.2 million . There were no performance shares vested during the year ended September 30, 2015 . The total intrinsic value of performance shares vested during the year ended September 30, 2014 was $2.2 million . We measure compensation expense related to performance shares based on the fair value of the awards at their date of grant. The grant-date fair value of performance shares that vest based on the satisfaction of a performance condition is the WGL closing stock price on the day prior to the grant date, which was $ 57.67 for performance shares granted in fiscal 2016. The grant-date fair value of performance shares that vest based on the satisfaction of a market condition is estimated using a Monte Carlo simulation model and the following assumptions: Fair Value Assumptions Years Ended September 30, 2016 2015 2014 Expected stock-price volatility (a) 19.10 % 18.30 % 19.10 % Dividend yield (b) — 4.18 % 3.93 % Weighted average grant-date fair value $ 67.30 $ 44.44 $ 42.88 (a) Expected stock-price volatility is based on the daily historical volatility of our common shares for the past three fiscal years. (b) The dividend yield represents our annualized dividend yield on the closing market price of our common stock at the date of the grant. Performance shares granted in fiscal year 2016 accrue dividend equivalents and, therefore, this assumption is not used when determining the grant-date fair value. We recognize compensation expense related to performance shares over the three-year requisite service period. Compensation expense for performance shares that vest based on the satisfaction of a performance condition is recognized for awards that ultimately vest. Compensation expense for performance shares that vest based on the satisfaction of a market conditions is recognized if the requisite service is rendered, but is not adjusted to reflect the ultimate achievement of the market condition. Performance Units The following table summarizes information regarding performance unit activity during the fiscal year ended September 30, 2016 . Performance Unit Activity Year Ended September 30, 2016 Number of Units (a) Non-vested and outstanding, beginning of year 12,685,633 Granted 5,152,000 Vested (3,858,799 ) Cancelled/forfeited (254,116 ) Non-vested and outstanding, end of year 13,724,718 (a) The number of performance units vested related to 11,199,395 non-vested performance units outstanding at year-end may range from zero to 200 percent of this number based on our satisfaction of the market condition for total shareholder return relative to a selected peer group of companies. For 2,525,323 non-vested performance units outstanding at year-end, the number of performance units vested may range from zero to 200% of this number based on our satisfaction of the performance condition for the return on equity ratio achieved during the performance period. The total fair value of performance units outstanding at September 30, 2016 for the units expected to vest in the future was $20.2 million . As of September 30, 2016 and 2015 , we recorded a current and deferred liability of $13.6 million and $13.3 million , respectively, related to our performance units. The current liability was recorded in "Accounts payable and other accrued liabilities—other" in the amounts of $6.9 million and $ 6.4 million at September 30, 2016 and 2015 , respectively. The deferred liability was recorded in “Deferred Credits—other” in the amounts of $ 6.7 million and $ 6.9 million , at September 30, 2016 and 2015 , respectively. During the fiscal year ended September 30, 2016 , we paid $ 6.4 million in cash to settle performance unit awards. During the fiscal year ended September 30, 2015, we did not make any cash payments to settle performance unit awards. Our performance units are liability awards as they settle in cash; therefore, we measure and record compensation expense for these awards based on their fair value at the end of each period until their vesting date. The percentage of the fair value that is accrued as compensation expense at the end of each period equals the percentage of the requisite service that has been rendered at that date. Consequently, fluctuations in earnings may result, that do not occur under the accounting requirements for our performance shares. The fair value of each performance unit that vests based on the satisfaction of a performance condition is $1.00. The amount of total compensation cost to be recognized for these performance units is a function of this fair value and the number of awards vested as a result of the performance condition being met and the requisite service provided. The fair value of each performance unit that vests based on the satisfaction of a market condition is estimated using a Monte Carlo simulation model and the following assumptions: Fair Value Assumptions September 30, 2016 10/1/2015 Grant 10/1/2014 Grant Expected stock-price volatility (a) 20.80 % 20.90 % (a)Expected stock-price volatility is based on the daily historical volatility of our common shares for a period equal to the remaining term of the performance units. The amount of total compensation cost to be recognized for these performance units is a function of this estimated fair value and the number of awards granted for which the requisite service is provided. Stock Options All remaining 5,318 stock options were exercised during fiscal year 2015; therefore, no remaining stock options were outstanding at September 30, 2016 or 2015. We received $0.2 million and $0.7 million from the exercise of stock options during the years ended September 30, 2015 and 2014. The related tax benefits realized for the fiscal years ended September 30, 2015 and 2014 were minimal and $0.1 million , respectively. STOCK GRANTS TO DIRECTORS Non-employee directors receive a portion of their annual retainer fee in the form of common stock through the Directors’ Stock Compensation Plan. Up to 270,000 shares of common stock may be awarded under the plan. Shares granted to directors were approximately 13,000 , 15,100 and 17,000 for the fiscal years ended September 30, 2016 , 2015 and 2014 , respectively. For those years, the weighted average fair value of the stock on the grant dates was $62.99 , $54.05 , and $40.06 , respectively. Shares awarded to the participants; (i) vest immediately and cannot be forfeited; (ii) may be sold or transferred (subject to WGL's stock ownership guidelines) and (iii) have voting and dividend rights. For both fiscal years ended September 30, 2016 and 2015 , WGL recognized stock-based compensation expense related to stock grants of $0.8 million , net of related income tax benefits of $0.3 million , respectively. For the year ended September 30, 2014 , WGL recognized stock-based compensation expense related to stock grants of $0.7 million , net of related income tax benefits of $0.3 million .

Environmental Matters

Environmental Matters	12 Months Ended
	Sep. 30, 2016
Environmental Remediation Obligations [Abstract]
Environmental Matters	ENVIRONMENTAL MATTERS We are subject to federal, state and local laws and regulations related to environmental matters. These laws and regulations may require expenditures over a long time frame to control environmental effects. Almost all of the environmental liabilities we have recorded are for costs expected to be incurred to remediate sites where we or a predecessor affiliate operated MGPs. Estimates of liabilities for environmental response costs are difficult to determine with precision because of the various factors that can affect their ultimate level. These factors include, but are not limited to, the following: • the complexity of the site; • changes in environmental laws and regulations at the federal, state and local levels; • the number of regulatory agencies or other parties involved; • new technology that renders previous technology obsolete or experience with existing technology that proves ineffective; • the level of remediation required; and • variations between the estimated and actual period of time that must be dedicated to respond to an environmentally-contaminated site. Washington Gas has identified up to ten sites where it or its predecessors may have operated MGPs. Washington Gas last used any such plant in 1984. In connection with these operations, we are aware that coal tar and certain other by-products of the gas manufacturing process are present at or near some former sites, and may be present at others. Based on the information available to us, we have concluded that none of the sites are likely to present an unacceptable risk to human health or the environment, and either the appropriate remediation is being undertaken or Washington Gas believes no remediation is necessary. At September 30, 2016 and 2015 , Washington Gas reported a liability of $8.2 million and $6.6 million , respectively, on an undiscounted basis related to future environmental response costs, which included the estimated costs for four MGP sites. These estimates principally include the minimum liabilities associated with a range of environmental response costs expected to be incurred at the sites identified. At September 30, 2016 and 2015 , Washington Gas estimated the maximum liability associated with all of its sites to be approximately $18.6 million and $17.2 million , respectively. The estimates were determined by Washington Gas’ environmental experts, based on experience in remediating MGP sites and advice from legal counsel and environmental consultants. The variation between the recorded and estimated maximum liability primarily results from differences in the number of years that will be required to perform environmental response processes at each site and the extent of remediation that may be required. Washington Gas received a letter in February 2016 from the District of Columbia and National Park Service regarding the Anacostia River Sediment Project, indicating that the District of Columbia is conducting a remedial investigation and feasibility study of the river to determine if and what cleanup measures may be required and to prepare a natural resource damage assessment. The sediment project draft report identifies one of Washington Gas’ former MGP sites as one of thirteen potential environmental cleanup sites. We are not able to estimate the amount of potential damages or timing associated with the District of Columbia's environmental investigation on the Anacostia River at this time. However, it is likely that Washington Gas will be assessed a portion of the study costs, which the District of Columbia projects to be between $15 million and $20 million . An allocation methodology has not yet been established, and, therefore, Washington Gas’ portion of the study costs is not yet estimable. Washington Gas is currently conducting a separate remedial investigation and feasibility study of potential contamination in the Anacostia River associated with and adjacent to this former MGP site under a 2012 consent decree with the District of Columbia and federal governments. Regulatory orders issued by the PSC of MD allow Washington Gas to recover the costs associated with the sites applicable to Maryland over the period ending in 2025. Rate orders issued by the PSC of DC allow Washington Gas a three -year recovery of prudently incurred environmental response costs, and allow Washington Gas to defer additional costs incurred between rate cases. Regulatory orders from the SCC of VA have generally allowed the recovery of prudent environmental remediation costs to the extent they were included in the underlying financial data supporting an application for rate change. At September 30, 2016 and 2015 , Washington Gas reported a regulatory asset of $1.3 million and $1.8 million , respectively, for the portion of environmental response costs that are expected to be recoverable in future rates. We do not expect that the ultimate impact of these matters will have a material effect on our financial position, cash flows, capital expenditures, earnings or competitive position.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES OPERATING LEASES Minimum future rental payments under operating leases over the next five years and thereafter are as follows: Minimum Payments Under Operating Leases (In millions) 2017 $ 7.5 2018 7.5 2019 3.9 2020 3.7 2021 3.4 Thereafter 27.8 Total $ 53.8 Rent expense totaled $8.4 million , $6.0 million and $5.5 million in fiscal years ended September 30, 2016 , 2015 and 2014 , respectively. REGULATED UTILITY OPERATIONS Natural Gas Contracts—Minimum Commitments At September 30, 2016 , Washington Gas had service agreements with four pipeline companies that provide direct service for firm transportation and/or storage services. These agreements, which have expiration dates ranging from fiscal years 2017 to 2034 , require Washington Gas to pay fixed charges each month. Additionally, Washington Gas had agreements for other pipeline and peaking services with expiration dates ranging from 2017 to 2027. These agreements were entered into based on current estimates of growth of the Washington Gas system, together with other factors, such as current expectations of the timing and extent of unbundling initiatives in the Washington Gas service territory. The following table summarizes the minimum contractual payments that Washington Gas will make under its pipeline transportation, storage and peaking contracts, as well as minimum contractual payments to purchase natural gas at prices based on market conditions during the next five fiscal years and thereafter. Washington Gas Contract Minimums (In millions) Pipeline Contracts (a) Gas Purchase Commitments (b) 2017 $ 218.8 $ 467.8 2018 217.8 404.5 2019 232.3 357.7 2020 231.4 359.2 2021 222.7 385.3 Thereafter 1,261.0 3,897.9 Total $ 2,384.0 $ 5,872.4 (a) Represents minimum payments for natural gas transportation, storage and peaking contracts that have expiration dates through fiscal year 2034. (b) Includes known and reasonably likely commitments to purchase natural gas. Cost estimates are based on forward market prices at September 30, 2016 . When a customer selects a third party marketer to provide supply, Washington Gas generally assigns pipeline and storage capacity to unregulated third party marketers to deliver gas to Washington Gas’ city gate. In order to provide the gas commodity to customers who do not select an unregulated third party marketer, Washington Gas has a commodity acquisition plan to acquire the natural gas supply to serve the customers. To the extent these commitments are to serve its customers, Washington Gas has rate provisions in each of its jurisdictions that would allow it to continue to recover these commitments in rates. Washington Gas also actively manages its supply portfolio to ensure its sales and supply obligations remain balanced. This reduces the likelihood that the contracted supply commitments would exceed supply obligations. However, to the extent Washington Gas were to determine that changes in regulation would cause it to discontinue recovery of these costs in rates, Washington Gas would be required to charge these costs to expense without any corresponding revenue recovery. If this occurred, depending upon the timing of the occurrence, the related impact on our financial position, results of operations and cash flows would likely be significant. Silver Spring, Maryland Incident Washington Gas continues to support the investigation by the NTSB into the August 10, 2016 explosion and fire at an apartment complex on Arliss Street in Silver Spring, Maryland, the cause of which has not been determined. Additional information will be made available by the NTSB at the appropriate time. On November 2, 2016, two civil actions were filed in the District of Columbia Superior Court against WGL Holdings and Washington Gas (as well as a property management company that is not affiliated with WGL Holdings or Washington Gas), by residents of the apartment complex. In one lawsuit, twenty-nine plaintiffs seek unspecified damages for, among others, wrongful death and personal injury. The other action is a class action suit seeking total damages stated to be less than $5 million for, among others, property damage and various counts relating to the loss of the use of the premises. Both actions allege causes of action for negligence, product liability, and declaratory relief. We also understand from press reports that additional civil actions relating to this incident have been filed on behalf of individual residents of the apartment complex, but we have yet to be served for any such additional actions. We maintain excess liability insurance coverage from highly-rated insurers, subject to a nominal self-insured retention. We believe that this coverage will be sufficient to cover any significant liability to it that may result from this incident. Management is unable to determine a range of potential losses that are reasonably possible of occurring and therefore we have not recorded a reserve associated with this incident. Washington Gas was invited by the NTSB to be a party to the investigation and in that capacity continues to work closely with the NTSB to help determine the cause of this incident. Regulatory Contingencies Certain legal and administrative proceedings incidental to our business, including regulatory contingencies, involve WGL and/or its subsidiaries. In our opinion, we have recorded an adequate provision for probable losses or refunds to customers for regulatory contingencies related to these proceedings. District of Columbia Jurisdiction Investigation into Washington Gas’ Cash Reimbursement to Competitive Service Providers (CSPs) . On August 5, 2014, the Office of the People’s Counsel’s (OPC) of DC filed a complaint with the PSC of DC requesting that the Commission open an investigation into Washington Gas’ payments to CSPs to cash-out over-deliveries of natural gas supplies during the 2008-2009 winter heating season. OPC asserted that Washington Gas made excess payments in the amount of $2.4 million to CSPs. On December 19, 2014, the PSC of DC granted the OPC of DC’s request and opened a formal investigation. On October 27, 2015, the PSC of DC issued an order finding that Washington Gas, in performing the cash-out, had violated D.C. Code 34-1101’s requirement that no service shall be provided without Commission approval. The PSC of DC directed Washington Gas to provide calculations showing what the impact would have been had Washington Gas made volumetric adjustments to CSP deliveries as of April 2009, which Washington Gas calculates would result in a refund of approximately $2.4 million , which was recognized by WGL in fiscal year 2015. On February 3, 2016, the PSC of DC issued an order denying OPC’s application for reconsideration and granting in part, and denying in part, Washington Gas’ application for reconsideration. Washington Gas and OPC filed initial briefs on February 18, 2016, and reply briefs on February 29, 2016, on the issue of whether there is a more reasonable way to reconcile the over-deliveries by CSPs such as through volumetric adjustments or through cash payments. On August 11, 2016, The DC Commission issued an order requiring Washington Gas to refund approximately $2.4 million through the Actual Cost Adjustment ("ACA"). On August 26, 2016, Washington Gas filed its plan for implementing the $2.4 million refund within a 12-month period. The PSC of DC issued an Order on October 7, 2016, clarifying Washington Gas' refunding and reporting requirements. NON-UTILITY OPERATIONS WGL Energy Services enters into contracts to purchase natural gas and electricity designed to match the duration of its sales commitments, and to secure a margin on estimated sales over the terms of existing sales contracts. WGL Midstream enters into contracts to acquire, invest in, manage and optimize natural gas storage and transportation assets. Gas purchase commitments increased during fiscal year 2016 due to purchase commitments related to investment pipeline infrastructure and long-term sales agreements. The following table summarizes the minimum commitments and contractual obligations of WGL Energy Services and WGL Midstream for the next five fiscal years and thereafter. Contract Minimums WGL Energy Services WGL Midstream (In millions) Gas Purchase Commitments (a) Pipeline Contracts (b) Electric Purchase Commitments (c) Gas Purchase Commitments (d) Pipeline Contracts (b) Total 2017 $ 148.8 $ 3.2 $ 413.1 $ 464.5 $ 25.0 $ 1,054.6 2018 40.1 1.5 179.6 1,077.6 19.5 1,318.3 2019 16.7 0.8 78.2 1,512.2 63.1 1,671.0 2020 7.5 0.5 30.2 1,641.2 66.7 1,746.1 2021 0.4 0.4 1.7 1,622.4 65.5 1,690.4 Thereafter — 0.8 0.9 27,780.0 972.0 28,753.7 Total $ 213.5 $ 7.2 $ 703.7 $ 34,097.9 $ 1,211.8 $ 36,234.1 (a) Represents fixed price commitments with city gate equivalent deliveries. (b) Represents minimum payments for natural gas transportation and storage contracts that have expiration dates through fiscal year 2044. (c) Represents electric purchase commitments that are based on existing fixed price and fixed volume contracts. Includes $18.3 million of commitments related to renewable energy credits. (d) Includes known and reasonably likely commitments to purchase natural gas. Cost estimates are based on forward market prices as of September 30, 2016 . Certain of our gas purchase agreements have optionality, which may cause increases in these commitments. Financial Guarantees WGL has guaranteed payments primarily for certain commitments on behalf of certain subsidiaries. At September 30, 2016 , these guarantees totaled $30.7 million , $212.6 million , $31.9 million and $321.1 million for Washington Gas, WGL Energy Services, WGL Energy Systems and WGL Midstream, respectively. At September 30, 2016 , WGL also had guarantees on behalf of other subsidiaries totaling $2.0 million . The amount of such guarantees is periodically adjusted to reflect changes in the level of WGL's financial exposure related to these commitments. For all of our financial guarantees, WGL may cancel any or all future obligations upon written notice to the counterparty, but WGL would continue to be responsible for the obligations created under the guarantees prior to the effective date of the cancellation. WGL has also guaranteed payments for certain of our external partners. At September 30, 2016 , these guarantees totaled $18.9 million and the fair value of these guarantees was insignificant. Antero Contract Washington Gas and WGL Midstream began purchasing natural gas on January 1, 2016, from Antero Resources Corporation (Antero) pursuant to certain natural gas purchase contracts. We purchase gas from Antero at invoiced prices based on an index specified in the contracts; however, contractual provisions allow either party to notify the other party if it believes the index price is no longer appropriate for the delivery point of the gas, and to trigger the negotiation of a new index price. If negotiations are unsuccessful, then the contract requires binding arbitration proceedings. When a new index price is determined under the contract, a "true up" of prior period invoices is required back to the date of initial notification. On November 16, 2015, due to significant changes to natural gas markets in and around the delivery point specified in the contracts, we provided notice to Antero invoking the provision requiring the negotiation of a new contractual index price. To date, negotiations have been unsuccessful and we are currently involved in arbitration proceedings to resolve this pricing dispute. Our Consolidated Financial Statements do not reflect the favorable effects of a change in the contractual index price. For the year ended September 30, 2016 , WGL Midstream has incurred approximately $15.2 million in losses associated with Antero’s use of the disputed index price.

Derivative and Weather Related

Derivative and Weather Related Instruments	12 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative and Weather-Related Instruments	DERIVATIVE AND WEATHER-RELATED INSTRUMENTS DERIVATIVE INSTRUMENTS Regulated Utility Operations Washington Gas enters into contracts that qualify as derivative instruments and are accounted for under ASC Topic 815. These derivative instruments are recorded at fair value on our balance sheets and Washington Gas does not currently designate any derivatives as hedges under ASC Topic 815. Washington Gas’ derivative instruments relate to: (i) Washington Gas’ asset optimization program; (ii) managing price risk associated with the purchase of gas to serve utility customers and (iii) managing interest rate risk. Asset Optimization. Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources during periods when these resources are not being used to physically serve utility customers. Specifically, Washington Gas utilizes its transportation capacity assets to benefit from favorable natural gas prices between different geographic locations and utilizes its storage capacity assets to benefit from favorable natural gas prices between different time periods. As part of this asset optimization program, Washington Gas enters into physical and financial derivative transactions in the form of forward, futures and option contracts with the primary objective of securing operating margins that Washington Gas will ultimately realize. The derivative transactions entered into under this program are subject to mark-to-market accounting treatment under ASC 820. Regulatory sharing mechanisms provide for the annual realized profit from these transactions to be shared between Washington Gas' shareholders and customers; therefore, changes in fair value are recorded through earnings, or as regulatory assets or liabilities to the extent that it is probable that realized gains and losses associated with these derivative transactions will be included in the rates charged to customers when they are realized. Unrealized gains and losses recorded to earnings may cause significant period-to-period volatility; this volatility does not change the 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 fiscal year ended September 30, 2016 was a net gain of $43.8 million including an unrealized gain of $12.0 million . During the fiscal year ended September 30, 2015 we recorded a net gain of $27.9 million including an unrealized loss of $6.3 million . During the fiscal year ended September 30, 2014 we recorded a net loss of $35.4 million including an unrealized loss of $66.2 million . Managing Price Risk. To manage price risk associated with acquiring natural gas supply for utility customers, Washington Gas enters into physical and financial derivative transactions in the form of forward, option and other contracts, as authorized by its regulators. Any gains and losses associated with these derivatives are recorded as regulatory liabilities or assets, respectively, to reflect the rate treatment for these economic hedging activities. Managing Interest-Rate Risk . Washington Gas may utilize derivative instruments that are designed to minimize the risk of interest-rate volatility associated with planned issuances of debt securities. Any gains and losses associated with these types of derivatives are recorded as regulatory liabilities or assets, respectively, and amortized in accordance with regulatory requirements, typically over the life of the related debt. In May 2016, Washington Gas entered into a forward starting interest rate swap, with a notional amount of $125.0 million related to the expected issuance of 30-year debt in late 2016. The change in the fair value of the interest rate swap was reported as a regulatory asset. In September 2016, this forward starting interest rate swap agreement was terminated. Non-Utility Operations Asset Optimization. WGL Midstream enters into derivative contracts for the purpose of optimizing its storage and transportation capacity as well as managing the transportation and storage assets on behalf of third parties. WGL Midstream does not designate these derivatives as hedges under ASC Topic 815; therefore, changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations and may cause significant period-to-period volatility in earnings. Managing Price Risk . WGL Energy Services enters into certain derivative contracts as part of its strategy to manage the price risk associated with the sale and purchase of natural gas and electricity. WGL Energy Services designates a portion of these physical contracts related to the purchase of natural gas and electricity to serve our customers as "normal purchases and normal sales" and therefore, they are not subject to the fair value accounting requirements of ASC Topic 815. Derivative instruments not designated as "normal purchases and normal sales" are recorded at fair value on our consolidated balance sheets, and changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations, which may cause significant period-to-period volatility in earnings. WGL Energy Services does not designate derivatives as hedges under ASC Topic 815. Managing Interest-Rate Risk . WGL utilizes derivative instruments that are designed to limit the risk of interest-rate volatility associated with future debt issuances. At September 30, 2016, WGL had $250 million of forward starting interest rate swaps, which hedge the variability in future interest payments associated with WGL's expected issuance of 30-year debt in January 2018. WGL designated these interest rate swaps as cash flow hedges. The effective portion of changes in fair value is reported as a component of other comprehensive income (loss) and reclassified into earnings in the same line item associated with the forecasted transaction and in the same period or periods during which the hedged transaction affects earnings. Any ineffective portion of these derivatives will be recognized directly through earnings as interest expense. There has been no ineffectiveness recorded to income associated with these hedges. WGL had also elected cash flow hedge accounting for interest rate swaps, that settled with the issuance of the related debt issuance in the first quarter of fiscal 2015. The effective portion of the gains and losses on the hedge were recorded within other comprehensive income (loss) and are amortized over the life of the debt (through 2044). The amortization was minimal for the fiscal years ended September 30, 2016 and 2015 . Consolidated Operations Reflected in the tables below is information for WGL as well as Washington Gas. The information for WGL includes derivative instruments for both utility and non-utility operations. At September 30, 2016 and 2015 , respectively, the absolute notional amounts of our derivatives are as follows: Absolute Notional Amounts of Open Positions on Derivative Instruments Derivative transactions WGL Holdings Washington Gas September 30, 2016 Notional Amounts Natural Gas (In millions of therms) Asset optimization & trading 21,084.5 12,725.0 Retail sales 50.2 — Other risk-management activities 1,789.0 1,309.0 Electricity (In millions of kWhs) Retail sales 4,377.5 — Other risk-management activities (a) 21,070.4 — Interest Rate Swaps (In millions of dollars) $ 250.0 $ — September 30, 2015 Natural Gas (In millions of therms) Asset optimization & trading 20,829.2 13,316.7 Retail sales 52.2 — Other risk-management activities 1,811.7 1,381.8 Electricity (In millions of kWhs) Retail sales 4,292.7 — Other risk-management activities (a) 19,965.7 — Interest Rate Swaps (In millions of dollars) $ 125.0 $ — (a) Comprised primarily of financial swaps, financial transmission rights and physical forward purchases. The following tables present the balance sheet classification for all derivative instruments as of September 30, 2016 and 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 September 30, 2016 Gross Derivative Assets Gross Derivative Liabilities Gross Derivative Assets Gross Derivative Liabilities Netting of Collateral Total (a) Current Assets—Derivatives $ 24.0 $ (5.5 ) $ — $ — $ — $ 18.5 Deferred Charges and Other Assets—Derivatives 55.6 (0.6 ) — — — 55.0 Current Liabilities—Derivatives 18.3 (113.2 ) — — 12.6 (82.3 ) Deferred Credits—Derivatives 6.4 (279.3 ) 0.2 (43.1 ) 11.6 (304.2 ) Total $ 104.3 $ (398.6 ) $ 0.2 $ (43.1 ) $ 24.2 $ (313.0 ) 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 September 30, 2016 Gross Gross Netting of Total (a) Current Assets—Derivatives $ 11.7 $ (4.4 ) $ — $ 7.3 Deferred Charges and Other Assets—Derivatives 26.2 (0.6 ) — 25.6 Current Liabilities—Derivatives 1.9 (60.2 ) — (58.3 ) Deferred Credits—Derivatives — (232.0 ) — (232.0 ) Total $ 39.8 $ (297.2 ) $ — $ (257.4 ) 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 September 30, 2016 or 2015 . The following tables present all gains and losses associated with derivative instruments for the years ended September 30, 2016 , 2015 and 2014 . Gains and Losses on Derivative Instruments (In millions) WGL Holdings, Inc. Washington Gas Fiscal Year Ended September 30, 2016 2015 2014 2016 2015 2014 Recorded to income Operating revenues—non-utility $ 5.8 $ 71.3 $ (47.9 ) $ — $ — $ — Utility cost of gas 12.1 (14.5 ) (87.3 ) 12.1 (14.5 ) (87.3 ) Non-utility cost of energy-related sales 33.5 (43.7 ) 36.2 — — — Other income-net — — (1.1 ) — — — Interest expense (0.2 ) (0.6 ) (0.2 ) — — — Recorded to regulatory assets Gas costs 13.9 (18.4 ) (143.3 ) 13.9 (18.4 ) (143.3 ) Other (a) (7.3 ) — 0.2 (7.3 ) — 0.2 Recorded to other comprehensive income (b) (39.3 ) (11.3 ) (1.5 ) — — — Total $ 18.5 $ (17.2 ) $ (244.9 ) $ 18.7 $ (32.9 ) $ (230.4 ) (a) Represents the settlement of Washington Gas' forward starting interest rate swap in September 2016. (b) Represents the effective portion of our cash flow hedges. Collateral WGL utilizes standardized master netting agreements, which facilitate the netting of cash flows into a single net exposure for a given counterparty. As part of these master netting agreements, cash, letters of credit and parental guarantees may be required to be posted or obtained from counterparties in order to mitigate credit risk related to both derivatives and non-derivative positions. Under WGL’s offsetting policy, collateral balances are offset against the related counterparties’ derivative positions to the extent the application would not result in the over-collateralization of those derivative positions on the balance sheet. The table below presents collateral positions at September 30, 2016 and 2015 , respectively. Collateral Not Offset Against Derivative Assets and Liabilities (In millions) September 30, 2016 Collateral deposits posted with counterparties Cash collateral held representing an obligation Washington Gas $ 4.3 $ 0.1 WGL Energy Services 9.1 — WGL Midstream 18.5 5.4 September 30, 2015 Washington Gas $ 3.5 $ 3.8 WGL Energy Services 12.4 — WGL Midstream 3.5 0.4 Any collateral posted that is not offset against derivative assets and liabilities is included in “Other prepayments” in the accompanying balance sheets. Collateral received and not offset against derivative assets and liabilities is included in “Customer deposits and advance payments” in the accompanying balance sheets. Certain derivative instruments of WGL, Washington Gas, WGL Energy Services and WGL Midstream contain contract provisions that require collateral to be posted if the credit rating of Washington Gas or WGL falls below certain levels or if counterparty exposure to WGL, Washington Gas, WGL Energy Services or WGL Midstream exceeds a certain level. Due to counterparty exposure levels, at September 30, 2016 , WGL Energy Services posted $5.5 million of collateral related to its derivative liabilities that contained credit-related contingent features. At September 30, 2015 , WGL Energy Services posted $10.3 million of collateral related to these aforementioned derivative liabilities. At September 30, 2016 , WGL was required to post $6.5 million of collateral related to a derivative liability that contained a credit-related contingent feature. At September 30, 2015 , WGL was not required to post any collateral related to its derivative liabilities that contained credit-related contingent features. At both September 30, 2016 and 2015 , Washington Gas and WGL Midstream were not required to post any collateral related to their respective derivative liabilities that contained credit-related contingent features. The following table shows the aggregate fair value of all derivative instruments with credit-related contingent features that are in a liability position, as well as the maximum amount of collateral that would be required if the most intrusive credit-risk-related contingent features underlying these agreements were triggered on September 30, 2016 and 2015 , respectively. Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features (In millions) WGL Holdings, Inc. Washington Gas September 30, 2016 Derivative liabilities with credit-risk-contingent features $ 53.9 $ 11.3 Maximum potential collateral requirements 41.4 11.3 September 30, 2015 Derivative liabilities with credit-risk-contingent features $ 61.7 $ 18.9 Maximum potential collateral requirements 54.6 18.8 We do not enter into derivative contracts for speculative purposes. Concentration of Credit Risk We are exposed to credit risk from derivative instruments with wholesale counterparties, which is represented by the fair value of these instruments at the reporting date. We actively monitor and work to minimize counterparty concentration risk through various practices. At September 30, 2016 , two counterparties each represented over 10% of Washington Gas’ credit exposure to wholesale derivative counterparties for a total credit risk of $36.6 million ; three counterparties each represented over 10% of WGL Energy Services’ credit exposure to wholesale derivative 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 $26.9 million . WEATHER-RELATED INSTRUMENTS WGL Energy Services utilizes weather-related instruments for managing the financial effects of weather risks. These instruments cover a portion of WGL Energy Services’ estimated revenue or energy-related cost exposure to variations in heating or cooling degree days. These contracts provide for payment to WGL Energy Services of a fixed-dollar amount for every degree day over or under specific levels during the calculation period depending upon the type of contract executed. During the years ended September 30, 2016 , 2015 and 2014 , WGL Energy Services recorded pre-tax gains of $1.7 million , $0.6 million and $3.4 million , respectively, related to these instruments.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	NOTE 15. 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 September 30, 2016 and 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 September 30, 2016 and 2015 , Level 2 financial assets and liabilities included energy-related physical and financial derivative transactions such as forward, option and other contracts for deliveries at active market locations, as well as our interest rate swaps. Level 3. Level 3 of the fair value hierarchy consists of assets or liabilities that are valued using significant unobservable inputs at the reporting date. These unobservable assumptions reflect our assumptions about estimates that market participants would use in pricing the asset or liability, including natural gas basis prices, annualized volatilities of natural gas prices, and electricity congestion prices. A significant change to any one of these inputs in isolation could result in a significant upward or downward fluctuation in the fair value measurement. These inputs may be used with industry standard valuation methodologies that result in our best estimate of fair value for the assets or liabilities at the reporting date. Our Risk Analysis and Mitigation (RA&M) Group determines the valuation policies and procedures. The RA&M Group reports to WGL’s Chief Financial Officer. In accordance with WGL’s valuation policy, we may utilize a variety of valuation methodologies to determine the fair value of Level 3 derivative contracts, including internally developed valuation inputs and pricing models. The prices used in our valuations are corroborated using multiple pricing sources, and we periodically conduct assessments to determine whether each valuation model is appropriate for its intended purpose. The RA&M Group also evaluates changes in fair value measurements on a daily basis. At September 30, 2016 and 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 September 30, 2016 and 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 September 30, 2016 Assets Natural gas related derivatives $ — $ 28.8 $ 54.0 $ 82.8 Electricity related derivatives — 0.6 20.9 21.5 Interest rate derivatives — 0.2 — 0.2 Total Assets $ — $ 29.6 $ 74.9 $ 104.5 Liabilities Natural gas related derivatives $ — $ (46.7 ) $ (318.2 ) $ (364.9 ) Electricity related derivatives — (3.8 ) (29.9 ) (33.7 ) Interest rate derivatives — (43.1 ) — (43.1 ) Total Liabilities $ — $ (93.6 ) $ (348.1 ) $ (441.7 ) 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 September 30, 2016 Assets Natural gas related derivatives $ — $ 15.4 $ 24.4 $ 39.8 Total Assets $ — $ 15.4 $ 24.4 $ 39.8 Liabilities Natural gas related derivatives $ — $ (21.2 ) $ (276.0 ) $ (297.2 ) Total Liabilities $ — $ (21.2 ) $ (276.0 ) $ (297.2 ) 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 September 30, 2016 and 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 ($264.1) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($2.021) - $3.290 Option Model Natural Gas Basis Price (per dekatherm) ($2.105) - $3.310 ($0.1) Annualized Volatility of Spot Market Natural Gas 25.5% - 869.9% Electricity related derivatives ($9.1) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($6.199) - $68.700 Washington Gas Light Company Natural gas related derivatives ($251.6) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($2.021) - $3.290 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 years ended September 30, 2016 and 2015 , respectively. Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs WGL Holdings Inc. Washington Gas Light Company (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Warrants Total Total - Natural Gas Fiscal Year Ended September 30, 2016 Balance at October 1, 2015 $ (309.7 ) $ (16.0 ) $ — $ (325.7 ) $ (281.1 ) Realized and unrealized gains (losses) Recorded to income 18.3 (21.4 ) — (3.1 ) 4.0 Recorded to regulatory assets—gas costs 4.2 — — 4.2 4.2 Transfers into Level 3 (0.8 ) — — (0.8 ) (0.2 ) Transfers out of Level 3 8.9 — — 8.9 9.0 Purchases — (2.4 ) — (2.4 ) — Settlements 15.0 30.7 — 45.7 12.5 Balance at September 30, 2016 $ (264.1 ) $ (9.1 ) $ — $ (273.2 ) $ (251.6 ) Fiscal Year Ended September 30, 2015 Balance at October 1, 2014 $ (294.7 ) $ (5.0 ) $ — $ (299.7 ) $ (270.6 ) Realized and unrealized gains (losses) Recorded to income (30.7 ) (32.3 ) — (63.0 ) (25.0 ) Recorded to regulatory assets—gas costs (30.9 ) — — (30.9 ) (30.9 ) Transfers into Level 3 5.4 — — 5.4 5.4 Transfers out of Level 3 3.6 — — 3.6 2.5 Purchases — 10.5 — 10.5 — Settlements 37.6 10.8 — 48.4 37.5 Balance at September 30, 2015 $ (309.7 ) $ (16.0 ) $ — $ (325.7 ) $ (281.1 ) Transfers between different levels of the fair value hierarchy may occur based on fluctuations in the valuation and on the level of observable inputs used to value the instruments from period to period. It is our policy to show both transfers into and out of the different levels of the fair value hierarchy at the fair value as of the beginning of the period. Transfers out of Level 3 during the fiscal year ended September 30, 2016 and 2015 were due to an increase in valuations using observable market inputs. Transfers into Level 3 during the fiscal year ended September 30, 2016 were due to an increase in unobservable market inputs used in valuations. The table below sets forth the line items on the statements of income to which amounts are recorded for the fiscal years ended September 30, 2016 , 2015 and 2014 , respectively, related to fair value measurements using significant Level 3 inputs. Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements WGL Holdings, Inc. Washington Gas Light Company (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Warrants Total Total - Natural Gas Fiscal Year Ended September 30, 2016 Operating revenues—non-utility $ 8.2 $ (26.5 ) $ — $ (18.3 ) $ — Utility cost of gas 4.0 — — 4.0 4.0 Non-utility cost of energy-related sales 6.1 5.1 — 11.2 — Total $ 18.3 $ (21.4 ) $ — $ (3.1 ) $ 4.0 Fiscal Year Ended September 30, 2015 Operating revenues—non-utility $ (5.7 ) $ 19.9 $ — $ 14.2 $ — Utility cost of gas (25.0 ) — — (25.0 ) (25.0 ) Non-utility cost of energy-related sales — (52.2 ) — (52.2 ) — Total $ (30.7 ) $ (32.3 ) $ — $ (63.0 ) $ (25.0 ) Fiscal Year Ended September 30, 2014 Operating revenues—non-utility $ (2.3 ) $ (22.1 ) $ — $ (24.4 ) $ — Utility cost of gas (69.4 ) — — (69.4 ) (69.4 ) Other income-net — — (1.1 ) (1.1 ) — Non-utility cost of energy-related sales (0.9 ) 16.4 — 15.5 — Total $ (72.6 ) $ (5.7 ) $ (1.1 ) $ (79.4 ) $ (69.4 ) Unrealized gains (losses) attributable to derivative assets and liabilities measured using significant Level 3 inputs were recorded as follows for the fiscal years ended September 30, 2016 , 2015 and 2014 , respectively: Unrealized Gains (Losses) Recorded for Level 3 Measurements WGL Holdings, Inc. Washington Gas Light Company (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Warrants Total Total - Natural Gas Fiscal Year Ended September 30, 2016 Recorded to income Operating revenues—non-utility $ 9.9 $ (2.3 ) $ — $ 7.6 $ — Utility cost of gas 0.3 — — 0.3 0.3 Non-utility cost of energy-related sales (0.4 ) 13.2 — 12.8 — Recorded to regulatory assets—gas costs (2.6 ) — — (2.6 ) (2.6 ) Total $ 7.2 $ 10.9 $ — $ 18.1 $ (2.3 ) Fiscal Year Ended September 30, 2015 Recorded to income Operating revenues—non-utility $ (2.2 ) $ 25.1 $ — $ 22.9 $ — Utility cost of gas (15.8 ) — — (15.8 ) (15.8 ) Non-utility cost of energy-related sales (1.7 ) (41.7 ) — (43.4 ) — Recorded to regulatory assets—gas costs (20.9 ) — — (20.9 ) (20.9 ) Total $ (40.6 ) $ (16.6 ) $ — $ (57.2 ) $ (36.7 ) Fiscal Year Ended September 30, 2014 Recorded to income Operating revenues—non-utility $ (5.0 ) $ (33.8 ) $ — $ (38.8 ) $ — Utility cost of gas (60.6 ) — — (60.6 ) (60.6 ) Non-utility cost of energy-related sales 3.7 30.0 — 33.7 — Other income-net — — (1.1 ) (1.1 ) — Recorded to regulatory assets—gas costs (109.9 ) — — (109.9 ) (109.9 ) Total $ (171.8 ) $ (3.8 ) $ (1.1 ) $ (176.7 ) $ (170.5 ) The following table presents the carrying amounts and estimated fair values of our financial instruments at September 30, 2016 and 2015 . WGL Holdings, Inc. Fair Value of Financial Instruments September 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 10.6 $ 10.6 $ 11.0 $ 11.0 Other short-term investments (a) $ 1.4 $ 1.4 $ 0.4 $ 0.4 Commercial paper (b) $ 269.0 $ 269.0 $ 332.0 $ 332.0 Project financing (b) $ 62.4 $ 62.4 $ — $ — Long-term debt (c) $ 1,444.3 $ 1,641.9 $ 944.2 $ 1,057.9 Washington Gas Light Company Fair Value of Financial Instruments September 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 5.0 $ 5.0 $ 4.3 $ 4.3 Other short-term investments (a) $ 1.4 $ 1.4 $ 0.4 $ 0.4 Commercial paper (b) $ 42.0 $ 42.0 $ 89.0 $ 89.0 Project financing (b) $ 62.4 $ 62.4 $ — $ — Long-term debt (c) $ 945.9 $ 1,126.4 $ 695.9 $ 811.9 (a) Balance is located in cash and cash equivalents in the accompanying balance sheets. These amounts may be offset by outstanding checks. (b) Balance is located in notes payable in the accompanying balance sheets. (c) Includes adjustments for current maturities and unamortized discounts, as applicable. Our money market funds are Level 1 valuations and their carrying amount approximates fair value. Other short-term investments are primarily overnight investment accounts; their carrying amount approximates fair value based on Level 2 inputs. The maturity of our commercial paper outstanding at both September 30, 2016 and 2015 is under 30 days. Due to the short term nature of these notes, the carrying cost of our commercial paper approximates fair value using Level 2 inputs. Due to the short term nature of our project financing arrangements, the carrying cost approximates fair value using Level 2 inputs. Neither WGL’s nor Washington Gas’ long-term debt is actively traded. The fair value of long-term debt was estimated based on the quoted market prices of the U.S. Treasury issues having a similar term to maturity, adjusted for the credit quality of the debt issuer, WGL or Washington Gas. Our long-term debt fair value measurement is classified as Level 3. Non Recurring Basis During the fiscal year ended September 30, 2016 , WGSW recognized a loss of $4.1 million associated with the impairment of its investment in direct financing leases from Nextility. The investment in direct financing leases is currently valued at $0.9 million , net of unamortized tax credits. We measured the impairment as the amount by which the carrying value exceeded the estimated fair value of the related collateral. The fair value was calculated based on the discounted cash flows estimated over the remaining asset life. The fair value of this investment was a Level 3 measurement. During the fiscal year ended September 30, 2015 , Washington Gas Resources recorded an impairment charge on its investment in ASDHI to its fair value using the income approach. The amount of the impairment was equivalent to the amount of the carrying value of $5.6 million and was due to management’s assumption of the current valuation and expected return from the investment. The fair value of this investment was a Level 3 measurement. During the fiscal year ended September 30, 2014 , Washington Gas recorded an impairment of its previous operations center by reducing the carrying amount of $22.3 million down to its fair value of $21.5 million , resulting in an impairment charge of $0.8 million based on the progress made towards selling the facility. The fair value of this investment is a Level 3 measurement. During the fiscal year ended September 30, 2014 , the SCC of VA disallowed full recovery of carrying costs related to an abandoned LNG storage facility. As a result, Washington Gas recorded an impairment charge of $1.9 million . The fair value of this investment was a Level 3 measurement.

Operating Segment Reporting

Operating Segment Reporting	12 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Operating Segment Reporting	OPERATING SEGMENT REPORTING We have four reportable operating segments: regulated utility, retail energy-marketing, commercial energy systems and midstream energy services. The division of these segments into separate revenue generating components is based upon regulation, products and services. Our chief operating decision maker is our Chief Executive Officer. During the first quarter of 2015, our chief operating decision maker began evaluating segment performance based on Earnings Before Interest and Taxes (EBIT). EBIT is defined as earnings before interest and taxes, less amounts attributable to non-controlling interests. 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 specializes in the investment, management, development and optimization of natural gas storage and transportation midstream infrastructure projects. 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 fiscal years ended September 30, 2016 , 2015 and 2014 . Operating Segment Financial Information (In thousands) Operating Revenues (a) Depreciation and Amortization Equity in Earnings of Unconsolidated Affiliates EBIT Total Assets Capital Expenditures Equity Method Investments Fiscal Year Ended September 30, 2016 Regulated utility $ 1,070,904 $ 116,129 $ — $ 228,219 $ 4,643,830 $ 393,501 $ — Retail energy-marketing 1,238,480 1,154 — 64,968 486,778 8,104 — Commercial energy systems (b) 89,072 15,201 7,620 21,992 885,734 128,780 66,100 Midstream energy services 6,619 107 6,186 7,807 485,099 — 237,391 Other activities — — — (3,184 ) 276,117 — — Eliminations (c) (55,516 ) (25 ) — (504 ) (718,853 ) — — Total consolidated $ 2,349,559 $ 132,566 $ 13,806 $ 319,298 $ 6,058,705 $ 530,385 $ 303,491 Fiscal Year Ended September 30, 2015 Regulated utility $ 1,328,191 $ 110,416 $ — $ 223,977 $ 4,228,813 $ 327,429 $ — Retail energy-marketing 1,306,758 671 — 46,629 463,141 28 — Commercial energy systems 51,813 10,733 2,095 9,688 689,910 136,749 63,521 Midstream energy services 3,191 129 2,623 (2,720 ) 237,839 85 73,363 Other activities — — 750 (9,667 ) 199,061 — — Eliminations (c) (30,123 ) (57 ) — (1,013 ) (557,405 ) — — Total consolidated $ 2,659,830 $ 121,892 $ 5,468 $ 266,894 $ 5,261,359 $ 464,291 $ 136,884 Fiscal Year Ended September 30, 2014 Regulated utility $ 1,443,800 $ 104,064 $ — $ 184,668 $ 3,956,571 $ 286,323 $ — Retail energy-marketing 1,310,279 756 1 14,015 388,651 76 — Commercial energy systems 40,679 6,178 1,953 6,863 521,049 108,363 66,810 Midstream energy services 16,555 124 771 8,412 209,682 — 28,076 Other activities — — 469 (11,539 ) 369,816 — 16 Eliminations (c) (30,366 ) (350 ) — (167 ) (615,934 ) — — Total consolidated $ 2,780,947 $ 110,772 $ 3,194 $ 202,252 $ 4,829,835 $ 394,762 $ 94,902 (a) Operating revenues are reported gross of revenue taxes. Revenue taxes of both the regulated utility and the retail energy-marketing segments include gross receipt taxes. Revenue taxes of the regulated utility segment also include public service commission fees, franchise fees and energy 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) As of August 2016, Commercial energy systems' operating revenues include revenues from non-controlling interest. Commercial energy systems' EBIT is adjusted for the effects of non-controlling interest. (c) Intersegment eliminations include any mark-to market valuations associated with trading activities 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. Fiscal Year Ended September 30, (In thousands) 2016 2015 2014 Total consolidated EBIT $ 319,298 $ 266,894 $ 202,252 Interest expense 52,310 50,511 37,738 Income tax expense 98,074 83,804 57,254 Dividends on Washington Gas Light Company preferred stock 1,320 1,320 1,320 Net income applicable to common stock $ 167,594 $ 131,259 $ 105,940

Other Investments

Other Investments	12 Months Ended
	Sep. 30, 2016
Other Investments [Abstract]
Other Investments	OTHER INVESTMENTS When determining how to account for our interests in other legal entities, WGL first evaluates if we are required to apply the variable interest entity (VIE) model of accounting to the entity. If the VIE model is not applicable, the entity is evaluated under the voting interest model. Under the VIE model, we have a controlling financial interest in a VIE (i.e. are the primary beneficiary) when we have current or potential rights that give us the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance combined with a variable interest that gives us the right to receive potentially significant benefits or the obligation to absorb potentially significant losses. When changes occur to the design of an entity, we reconsider whether it is subject to the VIE model. We continuously evaluate whether we have a controlling financial interest in a VIE. Under the voting interest model, we generally have a controlling financial interest in an entity where we currently hold, directly or indirectly, more than 50% of the voting rights or where we exercise control through substantive participating rights. However, we consider substantive rights held by other partners in determining if we hold a controlling financial interest, and in some cases, despite owning more than 50% of the common stock of an investee, an evaluation of our rights may result in the determination that we do not have a controlling financial interest. We reevaluate whether we have a controlling financial interest in these entities when our voting or substantive participating rights change. Unconsolidated affiliates are unconsolidated VIEs and other entities evaluated under the voting interest method in which we do not have a controlling financial interest, but over which we have varying degrees of influence. Where we have significant influence, the affiliates are accounted for as equity method investments. Where we do not have significant influence, the affiliates are accounted for under the cost method. Investments in, and advances to, affiliated companies are presented in the caption “Investments in unconsolidated affiliates” in the accompanying Consolidated Balance Sheets. WGL uses the Hypothetical Liquidation at Book Value (HLBV) methodology for certain equity method investments when the capital structure of the equity investment results in different liquidation rights and priorities than what is reflected by the underlying percentage ownership interests as defined by an equity investment agreement. For investments accounted for under the HLBV method, simply applying the percentage ownership interest to GAAP net income in order to determine earnings or losses does not accurately represent the income allocation and cash flow distributions that will ultimately be received by the investors. The equity investment agreements for ASD Solar, LP (ASD), Meade Pipeline Co LLC (Meade), Mountain Valley Pipeline, LLC (Mountain Valley) Stonewall Gas Gathering System (Stonewall System) have liquidation rights and priorities that are sufficiently different from the ownership percentages that the HLBV method was deemed appropriate. WGL also uses the HLBV methodology to allocate the earnings between the partners for its investment in SFGF. 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 five investments that qualify as VIEs: • Meade, • SunEdison, • Nextility, • ASD and • SFGF. WGL previously had a variable interest in a partnership partially owned by Crab Run; however, this partnership interest was sold during the fiscal year ended September 30, 2015. During the fiscal year ended September 30, 2015, WGL recognized a gain of $0.7 million , which was recorded in "Equity in earnings of unconsolidated affiliates" on WGL's statements of income, related to the sale of this interest. At September 30, 2016 , WGL and its subsidiaries are not the primary beneficiary for four of the five VIEs (Meade, SunEdison, Nextility, and ASD); therefore, we have not consolidated those 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. WGL's subsidiary, WGSW, Inc. is the primary beneficiary for SFGF and accordingly, we have consolidated that VIE entity. Meade In 2014, WGL through its subsidiary WGL Midstream, entered into a limited liability company agreement and formed Meade, a Delaware limited liability company with Transcontinental Gas Pipe Line Company, LLC (Williams) to invest in a regulated pipeline, a segment of Transco's Atlantic Sunrise project, called Central Penn Pipeline (Central Penn). Central Penn will be an approximately 185 -mile pipeline originating in Susquehanna County, Pennsylvania and extending to Lancaster County, Pennsylvania that will have the capacity to transport and deliver up to approximately 1.7 million dekatherms per day of natural gas. WGL Midstream plans to invest an estimated $410 million for a 55% interest in Meade. Although WGL Midstream holds greater than a 50% interest in Meade, Meade is accounted for under the equity method of accounting because WGL Midstream does not have the power to direct the activities most significant to the economic performance of Meade. Meade is accounted for under the HLBV equity method of accounting, and any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. At September 30, 2016 and 2015 , WGL Midstream held a $80.8 million and $30.5 million , respectively, equity method investment in Meade. WGL Midstream's maximum financial exposure is limited to its contributions made to the partnership, which were $80.1 million at September 30, 2016 . SunEdison and Nextility WGSW is party to two agreements to fund residential and commercial retail solar energy installations with two separate companies. WGSW has 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 Statement of Income. WGSW held a $30.9 million and $37.2 million combined investment in direct financing leases at September 30, 2016 and 2015 , respectively, of which $1.1 million and $2.0 million are current receivables recorded in “Accounts Receivable” in the accompanying Consolidated Balance Sheets at September 30, 2016 and 2015 , respectively. Additionally, we had balances of $13.3 million and $14.7 million of unamortized tax credits related to these investments in "Unamortized investment tax credits" on the accompanying Consolidated Balance Sheets at September 30, 2016 and 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) 2017 $ 2.2 2018 2.2 2019 2.1 2020 2.2 2021 2.2 Thereafter 28.5 Total $ 39.4 Minimum payments receivable exclude $9.7 million of residual values and $4.5 million in tax related items. Associated with these investments, WGSW holds $18.6 million of unearned income on its balance sheet. The initial direct costs (incurred in FY 2012) associated with these investments was $0.7 million . In April 2016, Nextility requested a restructuring of its direct financing lease arrangement with WGSW because Nextility was not collecting sufficient revenues related to the underlying thermal solar projects covered by the amended master lease agreement. During the year ended September 30, 2016, WGSW impaired its investment in Nextility by $4.1 million . Our maximum financial exposure from solar agreements is limited to WGSW's lease payment receivables and investment contributions made to these companies. On a quarterly basis, we review our direct financing leases for credit losses. Our review is based on multiple factors including historical losses, if any, economic factors currently impacting our counterparties' repayment ability, and other factors relevant to the business such as changes to regulatory and tax incentives. Our exposure is offset by the owned physical assets received as part of the transaction and the quick economic return for the investment through the investment tax credit/treasury grant proceeds and accelerated depreciation. On April 21, 2016, SunEdison filed a voluntary petition with the United States Bankruptcy Court for relief under Title 11 of the United States Code. EchoFirst Finance Company LLC, the subsidiary of SunEdison that is the party to our master purchase and lease agreements, is not a debtor in this bankruptcy proceeding. We will continue to monitor the impact of this development on our investment. ASD WGSW is also a limited partner in ASD, a limited partnership formed to own and operate a portfolio of residential solar projects, primarily rooftop photovoltaic power generation systems. As a limited partner, WGSW provided funding to the partnership but does not have power to direct the activities that most significantly affect the operations and economic performance of the entity. In January 2014, the funding commitment period expired for the partnership. WGSW’s maximum financial exposure is limited to its contributions made to the partnership, which were $72.6 million at September 30, 2016 . Our investment in ASD is accounted for under the HLBV equity method of accounting; any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statement of Income and are added to or subtracted from the carrying amount of WGSW’s investment balance. At September 30, 2016 and 2015 , WGSW held a $66.1 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 September 30, 2016 , the carrying amount of WGSW’s investment in ASD exceeded the amount of the underlying equity in net assets by $35.8 million due to WGSW recording additions to its investment in ASD’s net assets at fair value of contributions in accordance with GAAP. This basis difference is being amortized over the life of the assets. SFGF On August 24 2016, WGSW and a tax equity partner formed SFGF to acquire distributed generation solar projects in the State of Georgia that are developed by WGL Energy Systems. WGSW is the managing member and will provide cash equity equal to the purchase price of the solar projects less any contributions from the tax-equity partner. As of September 30, 2016 WGSW has contributed $1.7 million into the tax equity partnership and held a $2.3 million interest in SFGF. SFGF is consolidated into WGL's results of operations because under the VIE method of accounting, WGSW is the primary beneficiary as a result of its ability to direct the activities most significant to the economic performance of SFGF. WGL is the manager member of SFGF, the operations and maintenance provider, and the developer of the projects. Profits and losses are allocated between the partners under the HLBV method of accounting and the portion allocated to the tax equity partner is included in "Net income (loss) attributable to non-controlling interest" on the consolidated statement of income and is recorded to "Non-controlling interest" on the consolidated balance sheets. Non-VIE Investments Constitution In 2013, WGL Midstream invested in Constitution Pipeline Company, LLC (Constitution). At September 30, 2016 , WGL Midstream's total share of the cost of Constitution is estimated to be $95.5 million , over the term of the agreement, reflecting a 10% share in the pipeline venture. This natural gas pipeline venture 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 Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. The equity method is considered appropriate because Constitution is an LLC with specific ownership accounts and ownership between five and fifty percent resulting in WGL Midstream maintaining a more than minor influence over the partnership operating and financing policies. O n April 22, 2016, the New York State Department of Environmental Conservation (NYSDEC) denied Constitution's application for a Section 401 Water Quality Certification (Section 401 Certification) for the pipeline, which is necessary for the construction and operation of the pipeline. Constitution has stated that it remains committed to pursuing the project and that it intends to pursue all available options to challenge the legality and appropriateness of NYSDEC’s decision. In May, 2016, Constitution filed actions in the U.S. Circuit Court of Appeals for the Second Circuit and the U.S. District Court for the Northern District of New York, respectively, appealing the decision and a seeking declaratory judgment that the State of New York’s permitting authority is preempted by federal law. The courts have granted Constitution's motions to expedite the schedules for these legal actions. In light of the forgoing matters, Constitution has revised its target in-service date to the second half of 2018, which assumes that the legal challenge process is satisfactorily and promptly concluded. We can give no assurance, however, that Constitution’s efforts to obtain the Section 401 Certification will be successful. At September 30, 2016 and 2015, WGL Midstream held a $38.6 million and $33.1 million , respectively, equity method investment in Constitution. We have evaluated our investment in Constitution for other than temporary impairment as of September 30, 2016 . Our impairment assessment used income and market approaches in determining the fair value of our investment in Constitution, including consideration of the severity and duration of any decline in fair value of our investment in the project. Our key inputs included, but are not limited to, significant management judgments and estimates, including projections of the project’s cash flows, selection of a discount rate, market multipliers and probability weighting of potential outcomes of legal and regulatory proceedings. At this time, we do not have an other than temporary impairment and have not recorded any impairment charge to reduce the carrying value of our investment. If Constitution is ultimately unable to obtain the Section 401 Certification or other future developments or indicators of an unfavorable resolution arise subsequently, an impairment charge of up to substantially all of our investment in the capitalized project costs may be required. It is also possible that Constitution could incur certain supplier-related costs in the event of a prolonged delay or termination of the project. We will continue to monitor and update our impairment analysis as required. At September 30, 2016 , the maximum financial exposure is equivalent to total capital contributions made in Constitution on behalf of WGL Midstream, which was $35.2 million . Mountain Valley Pipeline In March 2015, WGL Midstream acquired a 7% equity interest in Mountain Valley Pipeline, LLC (Mountain Valley). On October 24, 2016, WGL Midstream acquired an additional 3% equity interest in Mountain Valley by assuming all of Vega Midstream MVP LLC's (Vega Energy) interest in the joint venture. WGL Midstream now owns a 10% interest in Mountain Valley. Prior to its acquisition of Vega Energy's interest, WGL Midstream was obligated under an agreement to finance all future capital commitments of Vega Energy. WGL Midstream had provided funding of $11.7 million as of September 30, 2016 related to this agreement. This amount was assumed by WGL Midstream as a part of the acquisition and WGL's obligation to fund Mountain Valley capital contributions on behalf of Vega Energy was terminated. 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. The pipeline is scheduled to be in service by December 2018. WGL Midstream expects to invest, in scheduled capital contributions through the in-service date of the pipeline, its pro rata share (based on its 10% equity interest) of project costs, an estimated aggregate amount of approximately $326.4 million . Prior to the acquisition of Vega Energy's interest, WGL Midstream held a $22.5 million and $9.8 million equity method investment in Mountain Valley at September 30, 2016 and 2015, respectively. The equity method is considered appropriate because Mountain Valley is an LLC with specific ownership accounts and ownership between five and fifty percent resulting in WGL Midstream maintaining a more than minor influence over the partnership operating and financing policies. The investment in MVP is accounted for under the HLBV equity method of accounting. Any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. Stonewall System In February 2016, WGL Midstream acquired a 35% equity interest in an entity that owns and operates certain assets known as the Stonewall Gas Gathering System (the Stonewall System). WGL Midstream paid $89.4 million to acquire the equity interest pursuant to an option that WGL Midstream previously acquired. The Stonewall System has the capacity to gather up to 1.4 billion cubic feet of natural gas per day from the Marcellus production region in West Virginia, and connects with an interstate pipeline system that serves markets in the mid-Atlantic region. WGL Midstream held a $95.5 million equity method investment in the Stonewall System at September 30, 2016 . The equity method is considered appropriate because the Stonewall Gas Gathering is an LLC with specific ownership accounts and ownership between five and fifty percent resulting in WGL Midstream maintaining a more than minor influence over the partnership operating and financing policies. In May 2016, another party to the deal exercised its option and invested in the Stonewall System. As a result, WGL Midstream's ownership decreased to 30% . The carrying amount of WGL Midstream's investment in the Stonewall System exceeded the amount of the underlying equity in net assets by $9.1 million that is being amortized over the life of the assets. The investment in Stonewall System is accounted for under the HLBV equity method of accounting. Any profits and losses are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. 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 fiscal year ended September 30, 2015 , Washington Gas Resources impaired its entire investment in ASDHI by its carrying value of $5.6 million based on management's assumption of the current valuation and expected return from the investment. The balance sheet location of the investments discussed in this footnote at September 30, 2016 and 2015 are as follows: Solar Investments Pipelines (in millions) Non-consolidated VIE's Consolidated VIE's Non-consolidated VIE's Non-consolidated Non VIE's Total As of September 30, 2016 Assets Investments in unconsolidated affiliates $ 66.1 $ — $ 80.8 $ 156.6 $ 303.5 Property, plant and equipment — 6.5 — — 6.5 Construction in progress — 6.7 — — 6.7 Investments in direct financing leases, capital leases 29.8 — — — 29.8 Accounts receivable 1.1 — — 9.2 (a) 10.3 Total assets $ 97.0 $ 13.2 $ 80.8 $ 165.8 $ 356.8 As of September 30, 2015 Assets Investments in unconsolidated affiliates $ 63.5 $ — $ 30.5 $ 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 $ 100.7 $ — $ 30.5 $ 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 fiscal year September 30, 2016 , 2015 and 2014 are as follows: WGL Holdings, Inc. Income Statement Location of Other Investments Solar Investments Pipelines Other (In millions) Non-consolidated VIE's Consolidated VIE's Non-consolidated VIE's Non-consolidated Non VIE's Non-consolidated VIE's Non-consolidated Non VIE's Total Fiscal Year Ended September 30, 2016 Equity in earnings of unconsolidated affiliates $ 7.6 $ — $ (0.1 ) $ 6.3 $ — $ — $ 13.8 Depreciation and amortization 0.3 — — — — — 0.3 Operations and maintenance 4.1 — — — — — 4.1 Other income (expenses) - net 3.1 — — (0.1 ) — — 3.0 Non-controlling interest — (0.6 ) — — — — (0.6 ) Fiscal Year Ended September 30, 2015 Equity in earnings of unconsolidated affiliates $ 2.1 $ — $ 0.1 $ 2.6 $ 0.7 $ — $ 5.5 Depreciation and amortization 0.3 — — — — — 0.3 Other income - net 3.2 — — — — (5.6 ) (2.4 ) Fiscal Year Ended September 30, 2014 Equity in earnings of unconsolidated affiliates $ 2.0 $ — $ 0.3 $ 1.0 $ (0.1 ) $ — $ 3.2 Depreciation and amortization 0.2 — — — — — 0.2 Other income - net 2.6 — — — — — 2.6

Related Party Transactions

Related Party Transactions	12 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS WGL and its subsidiaries engage in transactions in the ordinary course of business. Inter-company transactions and balances have been eliminated from the consolidated financial statements of WGL, except as described below. Washington Gas provides accounting, treasury, legal and other administrative and general support to affiliates, and files consolidated tax returns that include affiliated taxable transactions. Washington Gas bills its affiliates in accordance with regulatory requirements for the actual cost of providing these services, which approximates their market value. To the extent such billings are not paid, they are reflected in “Receivables from associated companies” on Washington Gas’ balance sheets. Washington Gas assigns or allocates these costs directly to its affiliates and, therefore, does not recognize revenues or expenses associated with providing these services. Washington Gas believes that allocations based on broad measures of business activity are appropriate for allocating expenses resulting from common services. Affiliate entities are allocated a portion of common services based on a formula driven by appropriate indicators of activity, as approved by management. In connection with billing for unregulated third party marketers, including WGL Energy Services and with other miscellaneous billing processes, Washington Gas collects cash on behalf of affiliates and transfers the cash in a reasonable time period. Cash collected by Washington Gas on behalf of its affiliates but not yet transferred is recorded in “Payables to associated companies” on Washington Gas’ balance sheets. Washington Gas obtains third-party project financing on behalf of the Federal government to provide funds during the construction of certain energy management services projects entered into under Washington Gas' area- wide contract. In connection with work completed under the area-wide contract, the construction work is performed by WGL Energy Systems on behalf of Washington Gas and an amount is recorded in "Payables to associated companies" for work performed by WGL Energy Systems for which cash has not been transferred. Refer to Note 4—Short Term Debt for further discussions of the project financing. The following table presents the receivables and payables from associated companies as of September 30, 2016 and September 30, 2015. Washington Gas Light Company Receivables / Payables from Associated Companies (In millions) September 30, 2016 September 30, 2015 Receivables from Associated Companies $ 13.8 $ 3.2 Payables to Associated Companies $ 65.8 $ 68.6 Washington Gas provides gas balancing services related to storage, injections, withdrawals and deliveries to all energy marketers participating in the sale of natural gas on an unregulated basis through the customer choice programs that operate in its service territory. These balancing services include the sale of natural gas supply commodities related to various peaking arrangements contractually supplied to Washington Gas and then partially allocated and assigned by Washington Gas to the energy marketers, including WGL Energy Services. Washington Gas records revenues for these balancing services pursuant to tariffs approved by the appropriate regulatory bodies. These related party amounts related to balancing services provided to WGL Energy Services have been eliminated in the consolidated financial statements of WGL. The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Washington Gas - Gas Balancing Service Charges (In millions) Years Ended September 30, 2016 2015 2014 Gas balancing service charge $ 26.8 $ 25.1 $ 26.6 As a result of these balancing services, an imbalance is created for volumes of natural gas received by Washington Gas that are not equal to the volumes of natural gas delivered to customers of the energy marketers. WGL Energy Services recognized accounts payable to Washington Gas of $0.8 million and $0.5 million at September 30, 2016 and 2015 , respectively, related to an imbalance in gas volumes. Due to regulatory treatment, these payables are not eliminated in the consolidated financial statements of WGL. Refer to Note 1—Accounting Policies for the Notes to Consolidated Financial Statements for further discussion of these imbalance transactions. Washington Gas participates in a 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 September 30, 2016 and 2015 , Washington Gas had balances of $4.2 million and $6.6 million , respectively, of purchased receivables from WGL Energy Services. On April 1, 2016 Washington Gas transferred WSS and ESS storage assets to WGL Midstream through a permanent release. Washington Gas held a base gas option associated with the WSS storage facility which gave Washington Gas the right to purchase 723,706 dekatherms of base gas at either: (i) the end of its service with WSS or (ii) the permanent release of its WSS storage capacity, for $ 0.594 per dekatherm. The option was transferred from Washington Gas to WGL Midstream in an equity transfer through WGL, concurrent with the transfer of storage assets. Washington Gas received cash of $0.9 million from WGL representing the value of the right to purchase base gas. This amount will be refunded to ratepayers through a credit to cost of gas. The effect of this equity transfer has been eliminated in the accompanying financial statements for WGL.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following tables show the changes in accumulated other comprehensive income (loss) for WGL and Washington Gas by component for the fiscal years ended September 30, 2016 and 2015 . WGL Holdings, Inc. Changes in Accumulated Other Comprehensive Loss by Component September 30, (In thousands) 2016 2015 Beginning Balance $ (14,236 ) $ (7,961 ) Qualified cash flow hedging instruments (a) (39,289 ) (11,309 ) Change in prior service cost (b) (891 ) 696 Amortization of actuarial loss (b) (936 ) (1,195 ) Current-period other comprehensive loss (41,116 ) (11,808 ) Income tax benefit related to other comprehensive loss (16,813 ) (5,533 ) Ending Balance $ (38,539 ) $ (14,236 ) (a) Cash flow hedging instruments represent interest rate swap agreements related to debt issuances. Refer to Note 14—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 10 — Pension and other post-retirement benefit plans for additional details. Washington Gas Light Company Changes in Accumulated Other Comprehensive Loss by Component September 30, (In thousands) 2016 2015 Beginning Balance $ (6,712 ) $ (6,413 ) Change in prior service cost (a) (891 ) 696 Amortization of actuarial loss (a) (936 ) (1,195 ) Current-period other comprehensive income loss (1,827 ) (499 ) Income tax expense benefit related to other comprehensive loss (709 ) (200 ) Ending Balance $ (7,830 ) $ (6,712 ) (a) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 10 — Pension and other post-retirement benefit plans for additional details.

Quarterly Financial Data

Quarterly Financial Data	12 Months Ended
	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	SUPPLEMENTARY FINANCIAL INFORMATION (Unaudited) QUARTERLY FINANCIAL DATA All adjustments necessary for a fair presentation have been included in the quarterly information provided below. Due to the seasonal nature of our business, we report substantial variations in operations on a quarterly basis. Quarter Ended (In thousands, except per share data) December 31 ( a) March 31 June 30 ( b) September 30 (c) Fiscal Year 2016 WGL Holdings, Inc. Operating revenues $ 613,384 $ 835,689 $ 440,587 $ 459,899 Operating income (loss) $ 117,509 $ 174,411 $ 13,683 $ (5,307 ) Net income (loss) $ 68,501 $ 106,618 $ 2,355 $ (9,110 ) Net income (loss) applicable to common stock $ 68,171 $ 106,288 $ 2,025 $ (8,890 ) Earnings (loss) per average share of common stock: Basic $ 1.37 $ 2.13 $ 0.04 $ (0.17 ) Diluted $ 1.36 $ 2.11 $ 0.04 $ (0.17 ) Washington Gas Light Company Operating revenues $ 295,246 $ 452,024 $ 187,077 $ 136,557 Operating income (loss) $ 98,977 $ 164,226 $ (20,528 ) $ (14,308 ) Net income (loss) $ 54,612 $ 94,433 $ (18,519 ) $ (17,412 ) Net income (loss) applicable to common stock $ 54,282 $ 94,103 $ (18,849 ) $ (17,742 ) Fiscal Year 2015 WGL Holdings, Inc. Operating revenues $ 749,237 $ 1,001,733 $ 441,173 $ 467,687 Operating income (loss) $ 121,842 $ 142,886 $ (17,567 ) $ 13,612 Net income (loss) $ 64,218 $ 81,785 $ (15,360 ) $ 1,936 Net income (loss) applicable to common stock $ 63,888 $ 81,455 $ (15,690 ) $ 1,606 Earnings (loss) per average share of common stock: Basic $ 1.28 $ 1.64 $ (0.32 ) $ 0.03 Diluted $ 1.28 $ 1.63 $ (0.32 ) $ 0.03 Washington Gas Light Company Operating revenues $ 387,193 $ 615,694 $ 190,345 $ 134,959 Operating income (loss) $ 114,623 $ 129,944 $ (6,729 ) $ (15,454 ) Net income (loss) $ 64,951 $ 74,694 $ (11,424 ) $ (19,543 ) Net income (loss) applicable to common stock $ 64,621 $ 74,364 $ (11,754 ) $ (19,873 ) (a) During the fist quarter of fiscal year 2016, there were no substantial variations in operations. During the first quarter of fiscal year 2015, WGL recorded an impairment charge of $ 5.6 million related to its investment in ASDHI. (b) During the third quarter of fiscal year 2016, WGL recorded an impairment charge of $ 3.0 million related to its investment in direct financing leases from Nextility. During the third quarter of fiscal year 2015, WGL recorded a $ 3.0 million liability for unrecovered government contracting costs under the Small Business Administration Development 8(a) Program and Washington Gas recorded approximately $ 0.5 million in transaction fees related to the sale of its Springfield Operations Center. Refer to Note 1—Accounting Policies of the Notes to Consolidated Financial Statements for further discussion of the impairments and to Note 13— Commitments and Contingencies for further discussion of the Antero Contract. (c) During the fourth quarter of fiscal year 2016, WGL recorded an additional impairment charge of $1.1 million related to its investment in direct financing leases from Nextility and $ 1.7 million in proceeds from an environmental insurance policy. During the fourth quarter of fiscal year 2015, Washington Gas recorded a one-time adjustment of $ 2.4 million as a result of charges associated with a regulatory proceeding. Refer to Note 1—Accounting Policies of the Notes to Consolidated Financial Statements for further discussion of the impairments, to Note 13— Commitments and Contingencies for further discussion of the Antero Contract and WGL Holdings, Inc Results of Operations for further discussion of the net proceeds related to the environmental insurance policy.

Schedule II

Schedule II	12 Months Ended
	Sep. 30, 2016
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts and Reserves	WGL Holdings, Inc. and Subsidiaries Schedule II—Valuation and Qualifying Accounts and Reserves Years Ended September 30, 2016, 2015 and 2014 Balance at Additions Charged To Balance Beginning Costs and Other at End of (In thousands) of Period Expenses Accounts (a) Deductions (b) Period 2016 Valuation and Qualifying Accounts Deducted from Assets in the Balance Sheet: Allowance for Doubtful Accounts $ 26,224 $ 13,051 $ 3,856 $ 15,792 $ 27,339 2015 Valuation and Qualifying Accounts Deducted from Assets in the Balance Sheet: Allowance for Doubtful Accounts $ 23,341 $ 18,250 $ 4,789 $ 20,156 $ 26,224 2014 Valuation and Qualifying Accounts Deducted from Assets in the Balance Sheet: Allowance for Doubtful Accounts $ 20,433 $ 15,874 $ 4,341 $ 17,307 $ 23,341 (a) Recoveries on receivables previously written off as uncollectible and unclaimed customer deposits, overpayments, etc., not refundable. (b) Includes deductions for purposes for which reserves were provided or revisions made of estimated exposure. Washington Gas Light Company Schedule II—Valuation and Qualifying Accounts and Reserves Years Ended September 30, 2016, 2015 and 2014 Balance at Additions Charged To Balance at Beginning Costs and Other End of (In thousands) of Period Expenses Accounts (a) Deductions (b) Period 2016 Valuation and Qualifying Accounts Deducted from Assets in the Balance Sheet: Allowance for Doubtful Accounts $ 19,254 $ 10,946 $ 3,806 $ 13,786 $ 20,220 2015 Valuation and Qualifying Accounts Deducted from Assets in the Balance Sheet: Allowance for Doubtful Accounts $ 19,209 $ 12,800 $ 4,686 $ 17,441 $ 19,254 2014 Valuation and Qualifying Accounts Deducted from Assets in the Balance Sheet: Allowance for Doubtful Accounts $ 17,498 $ 12,004 $ 4,198 $ 14,491 $ 19,209 (a) Recoveries on receivables previously written off as uncollectible and unclaimed customer deposits, overpayments, etc., not refundable. (b) Includes deductions for purposes for which reserves were provided or revisions made of estimated exposure.

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Consolidation	CONSOLIDATION OF FINANCIAL STATEMENTS The consolidated financial statements include the accounts of WGL and its subsidiaries during the fiscal years reported. Certain prior period amounts have been recast to conform to current period presentation. Refer to Note 9— Income Taxes , for a further discussion of prior year amounts reclassified as a result of the implementation of Income Taxes (Topic 740): Balance sheet Classification of Deferred Taxes , which was implemented retrospectively in the first quarter of fiscal year 2016. Inter-company transactions have been eliminated. Refer to Note 18— Related Party Transactions for a discussion of inter-company transactions. WGL has a variable interest in five investments that qualify as variable interest entities (VIEs). At September 30, 2016 , WGL and its subsidiaries are not the primary beneficiary for four of the five VIEs; therefore, we have not consolidated those VIE entities. WGSW is the primary beneficiary for one of the VIEs, SFGF, LLC (SFGF) and accordingly, it has been consolidated. Refer to Note 17— Other Investments for a discussion of VIEs and other investments.
Use of Estimates	USE OF ESTIMATES IN THE PREPARATION OF FINANCIAL STATEMENTS In accordance with generally accepted accounting principles in the United States of America (GAAP), we make certain estimates and assumptions regarding: (i) reported assets and liabilities; (ii) disclosed contingent assets and liabilities at the date of the financial statements and (iii) reported revenues, revenues subject to refund, and expenses during the reporting period. Actual results could differ from those estimates.
Property, Plant and Equipment	Washington Gas charges maintenance and repairs directly to operating expenses. Washington Gas capitalizes betterments and renewal costs, and calculates depreciation applicable to its utility gas plant in service primarily using a straight-line method over the estimated remaining life of the plant. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment (comprised principally of utility plant) are stated at original cost, including labor, materials, taxes and overhead costs incurred during the construction period. The cost of utility plant of Washington Gas includes an allowance for funds used during construction (AFUDC) that is calculated under a formula prescribed by our regulators in Maryland and the District of Columbia. Washington Gas capitalizes AFUDC as a component of construction overhead. In accordance with regulatory requirements, such rates include a component related to asset removal costs for Washington Gas. These asset removal costs are accrued through depreciation expense with a corresponding credit to “Regulatory liabilities—Accrued asset removal costs.” When Washington Gas retires depreciable utility plant and equipment, it charges the associated original costs to “Accumulated depreciation and amortization” and any related removal costs incurred are charged to “Regulatory liabilities—Accrued asset removal costs.” Washington Gas periodically reviews the adequacy of its depreciation rates by considering estimated remaining lives and other factors. For information about Asset Retirement Obligations (ARO’s), refer to the section entitled “Asset Retirement Obligations” .
Assets Held For Sale	ASSETS SALE - BUILDING During the year ended September 30, 2016 , Washington Gas completed the sale of the Springfield Operation Center for approximately $ 20.3 million , net of selling and administrative expenses of $ 0.5 million . As a result of the sale, an additional minimal loss was recorded to "Other expense-net" in the accompanying Consolidated Statements of Income. At September 30, 2015, the assets and liabilities associated with the Springfield Operations Center were reported at their expected selling price, less selling expenses, as "Assets held for sale" and "Liabilities held for sale" on WGL's and Washington Gas' balance sheets.
Impairment of Long-Lived Assets	IMPAIRMENT OF LONG-LIVED ASSETS Management regularly reviews property and equipment and other long-lived assets, including certain definite-lived intangible assets and our equity method investments for possible impairment. For our equity method investments, an impairment is recorded when the investment has experienced decline in value that is other-than-temporary. Additionally, if the projects in which we hold an investment recognize an impairment loss, we would record our proportionate share of that impairment loss and evaluate the investment for decline in value that is other-than-temporary. This review occurs quarterly, or more frequently if events or changes in circumstances indicate the carrying amount of the asset may not be recoverable.
Operating Leases	OPERATING LEASES We have classified the lease of our corporate headquarters as an operating lease. We amortize as rent expense the total of all scheduled lease payments (including lease payment escalations) and tenant allowances on a straight-line basis over the term of the lease. For this purpose, the lease term began on the date when the lessor commenced constructing the leasehold improvements which allowed us to occupy our corporate headquarters. Leasehold improvement costs are classified as “Property, Plant and Equipment” on the Balance Sheets, and are being amortized to depreciation and amortization expense on a straight-line basis over the 15 -year non-cancelable period of the lease. Refer to Note 13— Commitments and Contingencies for financial data for all of our operating leases. 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 Statement of Income.
Cash and Cash Equivalents	CASH AND CASH EQUIVALENTS We consider all investments with original maturities of three months or less to be cash equivalents. We did not have any restrictions on our cash balances that would impact the payment of dividends by WGL or our subsidiaries as of September 30, 2016 and 2015 .
Revenue Recognition	Non-Utility Operations Retail Energy-Marketing Segment. WGL Energy Services sells natural gas and electricity on an unregulated basis to residential, commercial and industrial customers both inside and outside the Washington Gas service territory. WGL Energy Services enters into indexed or fixed-rate contracts with residential, commercial and industrial customers for sales of natural gas and electricity. Customer contracts, which typically have terms less than 24 months, but may extend up to 5 years , allow WGL Energy Services to bill customers based upon metered gas and electricity usage. Usage is measured either on a cycle basis at customer premises or based on quantities delivered to the local utility, both of which may vary by month. The billing cycles for customers do not coincide with the accounting periods used for financial reporting purposes; therefore, WGL Energy Services accrues unbilled revenues for gas and electricity delivered, but not yet billed, at the end of each accounting period. In addition, WGL Energy Services periodically makes spot sales in the wholesale market due to specific delivery requirements or to reduce customer supply costs. Revenues are reflected in “Operating Revenues—Non utility.” WGL Energy Services procures natural gas and electricity supply under contract structures in which it assembles the various components of supply from multiple suppliers to match its customer requirements. The cost of natural gas and electricity for these purchases is recorded using the contracted volumes and prices in “Non-Utility cost of energy-related sales.” Commercial Energy Systems Segment. WGL Energy Systems recognizes income and expenses for all design-build construction contracts using the percentage-of-completion method in “Operating Revenues—Non-utility” and “Non-Utility cost of energy-related sales.” WGL Energy Systems also recognizes income from its distributed energy assets based on the terms of the related power purchase agreements. Renewable Energy Certificates (RECs) are generated by WGL Energy Systems after every 1,000 Kilowatt-hours (kWh) of electricity are produced by an eligible solar facility. WGL Energy Systems recognizes income on the sale of RECs based on the contractual terms and conditions of the sale. Refer to Note 17— Other Investments for discussion of our sale leaseback arrangements and equity method investments. Midstream Energy Services Segment. WGL Midstream nets its revenues and costs related to its trading activities in "Operating Revenues—Non-utility". Any profits and losses from WGL Midstream's pipeline investments are included in “Equity in earnings of unconsolidated affiliates” in the accompanying Consolidated Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. Refer to Note 17— Other Investments for discussion of our equity method investments. Regulated Utility Operations Revenues. For regulated deliveries of natural gas, Washington Gas reads meters and bills customers on a 19 -day monthly cycle basis. The billing cycles for customers do not coincide with the accounting periods used for financial reporting purposes; therefore, Washington Gas accrues unbilled revenues for gas delivered, but not yet billed, at the end of each accounting period. Cost of Gas. Washington Gas’ jurisdictional tariffs contain mechanisms that provide for the recovery of the cost of gas incurred on behalf of firm customers, including related pipeline transportation and storage capacity charges. Under these mechanisms, Washington Gas periodically adjusts its firm customers’ rates to reflect increases and decreases in these costs. Under or over-collections of gas costs in the current cycle are charged or credited to deferred charges or credits on the balance sheet as non-current regulatory assets or liabilities. Amounts deferred at the end of the cycle, August 31 of each year, are fully reconciled and transferred to current assets or liabilities under the balance sheet captions “Gas costs and other regulatory assets” and “Gas costs and other regulatory liabilities.” These balances are recovered or refunded to customers over the subsequent 12 month period. Revenue Taxes. Revenue taxes such as gross receipts taxes, Public Service Commission (PSC) fees, franchise fees and energy taxes are reported gross in operating revenues. During September 30, 2016, 2015 and 2014 $ 73.0 million and $83.5 million , and $84.3 million , respectively, were recorded to operating revenues.
Transportation Gas Imbalance	Transportation Gas Imbalance. Interruptible shippers and third party marketer shippers transport gas to Washington Gas’ distribution system as part of the unbundled services offered. The delivered volumes of gas from third party shippers into Washington Gas’ distribution system rarely equal the volumes billed to third party marketer customers, resulting in transportation gas imbalances. These imbalances are usually short-term in duration, and Washington Gas monitors the activity and regularly notifies the shippers when their accounts have an imbalance. In accordance with regulatory treatment, Washington Gas does not record a receivable from or liability to third party marketers associated with gas volumes related to these transportation imbalances but, rather, reflects the financial impact as a regulatory asset or liability related to its gas cost adjustment mechanism, thereby eliminating any profit or loss that would occur as a result of the imbalance. The regulatory treatment combines the imbalance for all marketers, including WGL Energy Services, into a single “net” adjustment to the regulatory asset or liability. Refer to Note 18— Related Party Transactions for further discussion of the accounting for these imbalance transactions.
Asset Optimization Program	Asset Optimization Program. Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources by entering into physical and financial transactions in the form of forwards, futures and option contracts for periods when these resources are not being used to physically serve utility customers. Refer to “Derivative Activities” below for further discussion of the accounting for derivative transactions entered into under this program. Regulatory sharing mechanisms in all three jurisdictions allow the profit from these transactions to be shared between Washington Gas’ customers and shareholders. All unrealized fair value gains and losses, and margins generated from the physical and financial settlement of these asset optimization contracts are recorded in utility cost of gas or, in the case of amounts to be shared with rate payers, regulatory assets/liabilities.
Storage Gas Valutation Methods	STORAGE GAS VALUATION METHODS 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.
Derivatives Activities	WEATHER-RELATED INSTRUMENTS Periodically, we purchase certain weather-related instruments, such as HDD derivatives and CDD derivatives. We account for these weather related instruments in accordance with Financial Accounting Standards Board Accounting Standards Codification (ASC) Subtopic 815-45, Derivatives and Hedging — Weather Derivatives . For weather insurance policies and HDD derivatives, benefits or costs are ultimately recognized to the extent actual HDDs fall above or below the contractual HDDs for each instrument. Benefits or costs are recognized for CDD derivatives when the average temperature exceeds or is below a contractually stated level during the contract period. Premiums for weather-related instruments are amortized based on the pattern of normal temperature days over the coverage period. Weather-related instruments for which we collect a premium are carried at fair value. Refer to Note 14— Derivative and Weather-Related Instruments for further discussion of our weather-related instruments. DERIVATIVE ACTIVITIES Regulated Utility . Washington Gas enters into both physical and financial derivative contracts for the purchase and sale of natural gas that are subject to mark-to-market accounting. Changes in the fair value of derivative instruments recoverable or refundable to customers and therefore subject to ASC Topic 980, Regulated Operations , are recorded as regulatory assets or liabilities while changes in the fair value of derivative instruments not affected by rate regulation are reflected in earnings. As part of its asset optimization program, Washington Gas enters into derivative contracts related to the sale and purchase of natural gas at a future price with the primary objective of securing operating margins that Washington Gas expects to ultimately realize. The derivatives used under this program may cause significant period-to-period volatility in earnings for the portion of net profits retained for shareholders; however, this earnings volatility will not change the realized margins that Washington Gas expects to earn. In accordance with ASC Topic 815, all financially and physically settled contracts under our asset optimization program are reported on a net basis in the statements of income in “Utility cost of gas”. From time to time, Washington Gas also utilizes derivative instruments that are designed to minimize the risk of interest-rate volatility associated with planned issuances of long-term debt. Gains or losses associated with these derivative transactions are deferred as regulatory assets or liabilities and amortized to interest expense in accordance with regulatory accounting requirements. Refer to Note 14— Derivative and Weather-Related Instruments for further discussion of our derivative activities. Non-Utility Operations. WGL Energy Services enters into both physical and financial contracts for the purchase and sale 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;” therefore, they are not subject to the mark-to-market accounting requirements of ASC Topic 815. WGL Energy Services records these derivatives as revenues or expenses depending on the nature of the economically hedged item. 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. The financial contracts and the portion of the physical contracts that qualify as derivative instruments are subject to the mark-to-market accounting requirements and are recorded on the balance sheet at fair value and are reflected in earnings. WGL Midstream nets financial and physical contracts in "Operating Revenues-Non-utility". WGL may, from time to time, designate interest rate swaps used to manage the interest rate risk associated with future debt issuances, as cash flow hedges. Any gains or losses arising from the effective portion of cash flow hedges are recorded in other comprehensive income and are amortized using the effective interest rate method into earnings over the same period as the hedged interest payments are made. Gains or losses arising from the ineffective portion of cash flow hedges are recognized in earnings immediately. Collateral WGL utilizes standardized master netting agreements, which facilitate the netting of cash flows into a single net exposure for a given counterparty. As part of these master netting agreements, cash, letters of credit and parental guarantees may be required to be posted or obtained from counterparties in order to mitigate credit risk related to both derivatives and non-derivative positions. Under WGL’s offsetting policy, collateral balances are offset against the related counterparties’ derivative positions to the extent the application would not result in the over-collateralization of those derivative positions on the balance sheet. Regulated Utility Operations Washington Gas enters into contracts that qualify as derivative instruments and are accounted for under ASC Topic 815. These derivative instruments are recorded at fair value on our balance sheets and Washington Gas does not currently designate any derivatives as hedges under ASC Topic 815. Washington Gas’ derivative instruments relate to: (i) Washington Gas’ asset optimization program; (ii) managing price risk associated with the purchase of gas to serve utility customers and (iii) managing interest rate risk. Asset Optimization. Washington Gas optimizes the value of its long-term natural gas transportation and storage capacity resources during periods when these resources are not being used to physically serve utility customers. Specifically, Washington Gas utilizes its transportation capacity assets to benefit from favorable natural gas prices between different geographic locations and utilizes its storage capacity assets to benefit from favorable natural gas prices between different time periods. As part of this asset optimization program, Washington Gas enters into physical and financial derivative transactions in the form of forward, futures and option contracts with the primary objective of securing operating margins that Washington Gas will ultimately realize. The derivative transactions entered into under this program are subject to mark-to-market accounting treatment under ASC 820. Regulatory sharing mechanisms provide for the annual realized profit from these transactions to be shared between Washington Gas' shareholders and customers; therefore, changes in fair value are recorded through earnings, or as regulatory assets or liabilities to the extent that it is probable that realized gains and losses associated with these derivative transactions will be included in the rates charged to customers when they are realized. Unrealized gains and losses recorded to earnings may cause significant period-to-period volatility; this volatility does not change the operating margins that Washington Gas expects to ultimately realize from these transactions through the use of its storage and transportation capacity resources. lected cash flow hedge accounting for interest rate swaps, that settled with the issuance of the related debt issuance in the first quarter of fiscal 2015. The effective portion of the gains and losses on the hedge were recorded within other comprehensive income (loss) and are amortized over the life of the debt (through 2044). 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. Any collateral posted that is not offset against derivative assets and liabilities is included in “Other prepayments” in the accompanying balance sheets. Collateral received and not offset against derivative assets and liabilities is included in “Customer deposits and advance payments” in the accompanying balance sheets. Non-Utility Operations Asset Optimization. WGL Midstream enters into derivative contracts for the purpose of optimizing its storage and transportation capacity as well as managing the transportation and storage assets on behalf of third parties. WGL Midstream does not designate these derivatives as hedges under ASC Topic 815; therefore, changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations and may cause significant period-to-period volatility in earnings. Managing Price Risk . WGL Energy Services enters into certain derivative contracts as part of its strategy to manage the price risk associated with the sale and purchase of natural gas and electricity. WGL Energy Services designates a portion of these physical contracts related to the purchase of natural gas and electricity to serve our customers as "normal purchases and normal sales" and therefore, they are not subject to the fair value accounting requirements of ASC Topic 815. Derivative instruments not designated as "normal purchases and normal sales" are recorded at fair value on our consolidated balance sheets, and changes in the fair value of these derivative instruments are reflected in the earnings of our non-utility operations, which may cause significant period-to-period volatility in earnings. WGL Energy Services does not designate derivatives as hedges under ASC Topic 815. Managing Interest-Rate Risk . WGL utilizes derivative instruments that are designed to limit the risk of interest-rate volatility associated with future debt issuances. Managing Price Risk. To manage price risk associated with acquiring natural gas supply for utility customers, Washington Gas enters into physical and financial derivative transactions in the form of forward, option and other contracts, as authorized by its regulators. Any gains and losses associated with these derivatives are recorded as regulatory liabilities or assets, respectively, to reflect the rate treatment for these economic hedging activities. Managing Interest-Rate Risk . Washington Gas may utilize derivative instruments that are designed to minimize the risk of interest-rate volatility associated with planned issuances of debt securities. Any gains and losses associated with these types of derivatives are recorded as regulatory liabilities or assets, respectively, and amortized in accordance with regulatory requirements, typically over the life of the related debt. 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.
Income Taxes	INCOME TAXES We recognize deferred income tax assets and liabilities for all temporary differences between the financial statement basis and the tax basis of assets and liabilities, including those that are currently excluded for ratemaking purposes of Washington Gas. Regulatory assets or liabilities, corresponding to such additional deferred income tax assets or liabilities, may be recorded to the extent recoverable from or payable to customers through the ratemaking process in future periods. Refer to Note 2— Regulated Operations for Washington Gas’ regulatory assets and liabilities associated with income taxes due from and to customers at September 30, 2016 and 2015 . Amounts applicable to income taxes due from and due to customers primarily represent differences between the book and tax basis of net utility plant in service. We amortize investment tax credits as reductions to income tax expense over the estimated service lives of the related properties.
Share-based Compensation	STOCK-BASED COMPENSATION We account for stock-based compensation expense in accordance with ASC Topic 718, Compensation—Stock Compensation, which requires us to measure and recognize stock-based compensation expense in our financial statements based on the fair value at the date of grant for our equity-classified share-based awards, which include performance shares granted to certain employees and shares issued to directors. For liability-classified share-based awards, which include performance units, we recognize stock-based compensation expense based on their fair value at the end of each reporting period. For both equity-classified and liability-classified share-based awards, we estimate forfeitures over the requisite service period when recognizing compensation expense; these estimates are periodically adjusted to the extent to which actual forfeitures differ from such estimates. Refer to Note 11— Stock-Based Compensation for further discussion of the accounting for our stock-based compensation plans.
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS Washington Gas accounts for its AROs in accordance with ASC Subtopic 410-20, Asset Retirement and Environmental Obligations—Asset Retirement Obligations. Our asset retirement obligations include the costs to cut, purge and cap Washington Gas' distribution and transmission system and plug storage wells upon their retirement. We also have asset retirement obligations associated with our distributed generation assets. These standards require recording the estimated retirement cost over the life of the related asset by depreciating the present value of the retirement obligation, measured at the time of the asset’s acquisition, and accreting the liability until it is settled. There are timing differences between the ARO-related accretion and depreciation amounts being recorded pursuant to GAAP and the recognition of depreciation expense for legal asset removal costs that we are currently recovering in rates. These timing differences are recorded as a reduction to “Regulatory liabilities—Accrued asset removal costs” in accordance with ASC Topic 980. We do not have any assets that are legally restricted related to the settlement of asset retirement obligations.
New Accounting Pronouncements	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 9 — Income taxes, for further discussion of this standard. OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required date of adoption Effect on the financial statements or other significant matters ASU 2015-03 and ASU 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost and Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements The standard requires an entity to present debt issuance costs in the balance sheet as a direct deduction of the debt liability in a manner consistent with its accounting treatment of debt discounts. The standard requires retrospective application. The new guidance does not change the recognition and measurement guidance for debt issuance costs. October 1, 2016 Implementation of these standards will result in a reduction of other deferred assets and long-term debt in our Consolidated Balance Sheets. The carrying amounts that would be reclassifed at September 30, 2016 is $9.3 million. 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 This standard is not expected to have an impact to net income nor a material impact on the balance sheet. ASU 2016-17, Consolidation (Topic 810): Interests Held through Related Parties that are Under Common Control The standard modifies the guidance issued with ASU 2015-02 to amend the consolidation guidance on how a reporting entity, that is the single decision maker of a VIE, should treat indirect interests in the entity held through related parties that are under common control with the reporting entity, when determining whether it is the primary beneficiary of that VIE. October 1, 2016 ASU 2016-17 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Entities that have already adopted the amendments in ASU 2015-02 are required to apply the amendments in this ASU retrospectively beginning with the fiscal year in which ASU 2015-02 was applied. We do not expect that the adoption of this standard will have a material impact on our financial statements. ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting This standard simplifies several aspects of the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and statutory tax withholding requirements. October 1, 2017 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-15, Statement of Cash Flows (Topic 230)—Classification of Certain Cash Receipts and Cash Payments (a consensus of the FASB Emerging Issues Task Force) This update provides guidance on the classification of certain cash receipts and payments in the statement of cash flows. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2014-09, Revenue from Contracts with Customers (Topic 606), including subsequent ASUs clarifying the guidance. ASU 2014-09 establishes a comprehensive revenue recognition model clarifying the method used to determine the timing and requirements for revenue recognition from contracts with customers. The disclosure requirements under the new standard will enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-01, Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The new standard significantly revises an entity’s accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-02, Leases (Topic 842) This standard requires recognition of a right-to-use asset and lease liability on the statement of financial position and disclosure of key information about leasing arrangements. The standard requires application using a modified retrospective approach. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. We may elect early adoption. ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments For credit losses on financial instruments, this standard changes the current incurred loss impairment methodology to an expected loss methodology and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. October 1, 2020 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.
Fair Value 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. 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. 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 September 30, 2016 and 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 fiscal year ended September 30, 2016 , Washington Gas Resources recorded an impairment charge of 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.
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. During the first quarter of 2015, our chief operating decision maker began evaluating segment performance based on Earnings Before Interest and Taxes (EBIT). EBIT is defined as earnings before interest and taxes, less amounts attributable to non-controlling interests. 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.
Investments	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 Statement 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. 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 may result in the determination that we do not have a controlling financial interest. We reevaluate whether we have a controlling financial interest in these entities when our voting or substantive participating rights change. Unconsolidated affiliates are unconsolidated VIEs and other entities evaluated under the voting interest method in which we do not have a controlling financial interest, but over which we have varying degrees of influence. Where we have significant influence, the affiliates are accounted for as equity method investments. Where we do not have significant influence, the affiliates are accounted for under the cost method. Investments in, and advances to, affiliated companies are presented in the caption “Investments in unconsolidated affiliates” in the accompanying Consolidated Balance Sheets. WGL uses the Hypothetical Liquidation at Book Value (HLBV) methodology for certain equity method investments when the capital structure of the equity investment results in different liquidation rights and priorities than what is reflected by the underlying percentage ownership interests as defined by an equity investment agreement. For investments accounted for under the HLBV method, simply applying the percentage ownership interest to GAAP net income in order to determine earnings or losses does not accurately represent the income allocation and cash flow distributions that will ultimately be received by the investors. The equity investment agreements for ASD Solar, LP (ASD), Meade Pipeline Co LLC (Meade), Mountain Valley Pipeline, LLC (Mountain Valley) Stonewall Gas Gathering System (Stonewall System) have liquidation rights and priorities that are sufficiently different from the ownership percentages that the HLBV method was deemed appropriate. WGL also uses the HLBV methodology to allocate the earnings between the partners for its investment in SFGF. 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. 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 Statement of Income and are added to or subtracted from the carrying amount of WGL’s investment balance. 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 Statement of Income and are added to or subtracted from the carrying amount of WGSW’s investment balance.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Sep. 30, 2016
Accounting Policies [Table] [Line Items]
Property, Plant, and Equipment at Original Cost	At September 30, 2016 and 2015 , 88.7% and 91.2% , respectively, of WGL’s consolidated original cost of property, plant and equipment was related to the regulated utility segment as shown below. Property, Plant and Equipment at Original Cost ($ In millions) September 30, 2016 2015 Regulated utility segment Distribution, transmission and storage $ 4,210.6 75.9 % $ 3,927.2 78.5 % General, miscellaneous and intangibles 435.2 7.9 424.8 8.5 Construction work in progress (CWIP) 273.1 4.9 210.4 4.2 Total regulated utility segment 4,918.9 88.7 4,562.4 91.2 Unregulated segments 624.1 11.3 441.5 8.8 Total $ 5,543.0 100.0 % $ 5,003.9 100.0 %
Lower-of-cost or market adjustments pre-tax increase (decrease) to net income	There were no lower-of-cost or market adjustment recorded to net income for Washington Gas the fiscal year ended September 30, 2016 . WGL Midstream recorded quarterly adjustments that netted to zero for the fiscal year ended September 30, 2016 . The following table shows the lower-of-cost or market adjustments recorded to net income for the years ended September 30, 2015 and 2014 . Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income (In millions) September 30, 2015 2014 WGL (a) Operating revenues - non-utility $ (21.5 ) $ (3.0 ) Washington Gas Utility cost of gas $ (1.3 ) $ (0.2 ) Total Consolidated $ (22.8 ) $ (3.2 ) (a) WGL includes WGL Midstream.
Changes in Asset Retirement Obligations	WGL Holdings, Inc. Changes in Asset Retirement Obligations (In millions) September 30, 2016 2015 Asset retirement obligations at beginning of year $ 207.7 $ 181.2 Liabilities incurred in the period 12.1 8.4 Liabilities settled in the period (a) (16.9 ) (14.6 ) Accretion expense 7.4 7.8 Revisions in estimated cash flows (b) — 24.9 Asset retirement obligations at the end of the year (c) $ 210.3 $ 207.7
Accounting standards adopted in the 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 9 — Income taxes, for further discussion of this standard.
Other newly issued accounting standards	OTHER NEWLY ISSUED ACCOUNTING STANDARDS Standard Description Required date of adoption Effect on the financial statements or other significant matters ASU 2015-03 and ASU 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost and Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements The standard requires an entity to present debt issuance costs in the balance sheet as a direct deduction of the debt liability in a manner consistent with its accounting treatment of debt discounts. The standard requires retrospective application. The new guidance does not change the recognition and measurement guidance for debt issuance costs. October 1, 2016 Implementation of these standards will result in a reduction of other deferred assets and long-term debt in our Consolidated Balance Sheets. The carrying amounts that would be reclassifed at September 30, 2016 is $9.3 million. 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 This standard is not expected to have an impact to net income nor a material impact on the balance sheet. ASU 2016-17, Consolidation (Topic 810): Interests Held through Related Parties that are Under Common Control The standard modifies the guidance issued with ASU 2015-02 to amend the consolidation guidance on how a reporting entity, that is the single decision maker of a VIE, should treat indirect interests in the entity held through related parties that are under common control with the reporting entity, when determining whether it is the primary beneficiary of that VIE. October 1, 2016 ASU 2016-17 is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Entities that have already adopted the amendments in ASU 2015-02 are required to apply the amendments in this ASU retrospectively beginning with the fiscal year in which ASU 2015-02 was applied. We do not expect that the adoption of this standard will have a material impact on our financial statements. ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting This standard simplifies several aspects of the accounting for share-based payment transactions, including accounting for income taxes, forfeitures, and statutory tax withholding requirements. October 1, 2017 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-15, Statement of Cash Flows (Topic 230)—Classification of Certain Cash Receipts and Cash Payments (a consensus of the FASB Emerging Issues Task Force) This update provides guidance on the classification of certain cash receipts and payments in the statement of cash flows. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2014-09, Revenue from Contracts with Customers (Topic 606), including subsequent ASUs clarifying the guidance. ASU 2014-09 establishes a comprehensive revenue recognition model clarifying the method used to determine the timing and requirements for revenue recognition from contracts with customers. The disclosure requirements under the new standard will enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-01, Financial Instruments (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities The new standard significantly revises an entity’s accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. October 1, 2018 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. ASU 2016-02, Leases (Topic 842) This standard requires recognition of a right-to-use asset and lease liability on the statement of financial position and disclosure of key information about leasing arrangements. The standard requires application using a modified retrospective approach. October 1, 2019 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements. We may elect early adoption. ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments For credit losses on financial instruments, this standard changes the current incurred loss impairment methodology to an expected loss methodology and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. October 1, 2020 We are in the process of evaluating the impact the adoption of this standard will have on our financial statements.
Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Changes in Asset Retirement Obligations	Washington Gas Light Company Changes in Asset Retirement Obligations (In millions) September 30, 2016 2015 Asset retirement obligations at beginning of year $ 205.9 $ 179.8 Liabilities incurred in the period 10.4 8.1 Liabilities settled in the period (a) (16.9 ) (14.6 ) Accretion expense 7.2 7.7 Revisions in estimated cash flows (b) — 24.9 Asset retirement obligations at the end of the year (c) $ 206.6 $ 205.9 (a) Fiscal year 2015 includes asset retirement obligations of $1.6 million related to the Springfield Operations Center that were reclassified to "Current Liabilities - Liabilities held for sale." The building was sold in 2016. (b) WGL revised its assumptions regarding the timing and amounts related to its obligation to cut, cap and purge pipeline. The revision is primarily driven by our accelerated pipeline replacement programs. (c) Includes short-term asset retirement obligations of $7.2 million and $7.0 million for fiscal year 2016 and 2015 , respectively.

Regulated Operations (Tables)

Regulated Operations (Tables)	12 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Schedule of Regulatory Assets and Liabilities	Regulatory Assets and Liabilities (In millions) Regulatory Assets Regulatory Liabilities September 30, 2016 2015 2016 2015 Current: Gas costs due from/to customers (a) $ 4.1 $ 1.7 $ 12.1 $ 22.6 Interruptible sharing (a) 0.9 3.3 0.6 2.6 Revenue normalization mechanisms for Maryland and Virginia (a) 6.6 — — 8.4 Plant recovery mechanisms 3.7 0.8 0.3 1.0 Total current $ 15.3 $ 5.8 $ 13.0 $ 34.6 Deferred: Accrued asset removal costs $ — $ — $ 310.8 $ 325.5 Deferred gas costs (a)(b) 179.9 190.7 — — Pension and other post-retirement benefits Other post-retirement benefit costs—trackers (c) — 0.1 — — Deferred pension costs—trackers (c) 29.8 38.0 — — ASC Topic 715 unrecognized costs/income (a)(d) Pensions 193.4 173.9 — — Other post-retirement benefits — — 113.9 104.4 Total pension and other post-retirement benefits 223.2 212.0 113.9 104.4 Other Income tax-related amounts due from/to customers (e) 33.6 31.7 3.6 4.2 Losses/gains on issuance and extinguishments of debt and interest-rate derivative instruments (a)(f) 17.5 11.1 1.5 1.6 Deferred gain on sale of assets (a) — — 1.0 1.4 Rights-of-way fees (a) 0.3 1.6 — — Business process outsourcing and related costs (a) 9.8 2.7 — — Non-retirement post-employment benefits (a)(g) 19.2 18.9 — — Deferred integrity management expenditures (a)(h) 8.5 5.1 — — Recoverable portion of abandoned LNG facility 4.3 5.0 — — Environmental response costs (a)(i) 1.3 1.8 — — Other regulatory expenses (a) 4.1 2.1 8.3 9.9 Total other $ 98.6 $ 80.0 $ 14.4 $ 17.1 Total deferred $ 501.7 $ 482.7 $ 439.1 $ 447.0 Total $ 517.0 $ 488.5 $ 452.1 $ 481.6 (a) Washington Gas does not earn its overall rate of return on these assets. Washington Gas is allowed to recover and required to pay, using short-term interest rates, the carrying costs related to billed gas costs due from and to its customers in the District of Columbia and Virginia jurisdictions. (b) Includes fair value of derivatives, which are not included in customer bills until settled. (c) Relates to the District of Columbia jurisdiction. (d) Refer to Note 10-Pension and Other Post-Retirement Benefit Plans for a further discussion of these amounts. (e) This balance represents amounts due from customers for deferred tax liabilities related to tax benefits on deduction flowed directly to customers prior to the adoption of income tax normalization for ratemaking purposes. (f) The losses or gains on the issuance and extinguishment of debt and interest-rate derivative instruments include unamortized balances from transactions executed in prior fiscal years. These transactions create gains and losses that are amortized over the remaining life of the debt as prescribed by regulatory accounting requirements. (g) Represents the timing difference between the recognition of workers compensation and short-term disability costs in accordance with generally accepted accounting principles and the way these costs are recovered through rates. (h) This balance represents amounts for deferred expenditures associated with Washington Gas’ Distribution Integrity Management Program (DIMP) in Virginia. (i) This balance represents allowed remediation expenditures at Washington Gas sites to be recovered through rates for Maryland and the District of Columbia. The recovery period is over several years.

Accounts Payable and Other Ac34

Accounts Payable and Other Accrued Liabilities (Tables)	12 Months Ended
	Sep. 30, 2016
Accounts Payable and 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. September 30, (In millions) 2016 2015 Accounts payable—trade $ 353.0 $ 277.3 Employee benefits and payroll accruals 34.4 31.4 Other accrued liabilities 18.0 16.4 Total $ 405.4 $ 325.1
Washington Gas Light Company
Accounts Payable and Accrued Liabilities [Line Items]
Accounts Payable and Other Accrued Liabilities	Washington Gas Light Company September 30, (In millions) 2016 2015 Accounts payable—trade $ 161.0 $ 122.2 Employee benefits and payroll accruals 32.2 29.5 Other accrued liabilities 11.8 7.6 Total $ 205.0 $ 159.3

Short-Term Debt (Tables)

Short-Term Debt (Tables)	12 Months Ended
	Sep. 30, 2016
Short-term Debt [Abstract]
Commited Credit Available	The following is a summary of committed credit available at September 30, 2016 and 2015 . Committed Credit Available (In millions) September 30, 2016 WGL (b) Washington Gas Total Consolidated Committed credit agreements Unsecured revolving credit facility, expires December 19, 2019 (a) $ 450.0 $ 350.0 $ 800.0 Less: Commercial Paper (227.0 ) (42.0 ) (269.0 ) Net committed credit available $ 223.0 $ 308.0 $ 531.0 Weighted average interest rate 0.73 % 0.46 % 0.69 % September 30, 2015 Committed credit agreements Unsecured revolving credit facility, expires April 3, 2017 (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 (Tables)

Long Term Debt (Tables)	12 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Long Term Debt Outstanding	The following tables show the outstanding notes as of September 30, 2016 and 2015 . Long-Term Debt Outstanding ($ In millions) WGL (a) Washington Gas Total Consolidated September 30, 2016 Long-term debt (b) $ 500.0 $ 946.0 $ 1,446.0 Unamortized discount (1.6 ) (0.1 ) (1.7 ) Total Long-Term Debt $ 498.4 $ 945.9 $ 1,444.3 Weighted average interest rate 2.50 % 5.12 % 4.21 % September 30, 2015 Long-term debt (b) $ 250.0 $ 721.0 $ 971.0 Unamortized discount (1.7 ) (0.1 ) (1.8 ) Less — Current maturities — 25.0 25.0 Total Long-Term Debt $ 248.3 $ 695.9 $ 994.2 Weighted average interest rate 3.66 % 5.58 % 5.08 % (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. ( b) Includes Senior Notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities.
Long-Term Debt Issuances and Retirements	The following tables show long-term debt issuances and retirements for the years ended September 30, 2016 and 2015 . Long-Term Debt Issuances and Retirements ($ In millions) Principal (b) Interest Rate Effective Cost Nominal Maturity Date Year Ended September 30, 2016 WGL (a) Issuances: 2/18/2016 $ 250.0 1.34 % (c) 1.34 % (c) 2/18/2018 Total $ 250.0 Washington Gas Issuances: 9/16/2016 $ 250.0 3.80 % 4.01 % (d) 3/15/2046 Total 250.0 Total consolidated issuances $ 500.0 Washington Gas Retirements: 1/18/2016 $ 25.0 5.17 % n/a 1/18/2016 Total $ 25.0 Year Ended September 30, 2015 WGL (a) Issuances: 10/24/2014 $ 100.0 2.25 % 2.42 % 11/1/2019 10/24/2014 125.0 4.60 % 5.11 % 11/1/2044 12/16/2014 25.0 4.60 % 5.53 % 11/1/2044 Total $ 250.0 Washington Gas Issuances: 12/15/2014 $ 50.0 4.24 % 4.41 % 12/15/2044 Total 50.0 Total consolidated issuances $ 300.0 Washington Gas Retirements: 8/9/2015 $ 20.0 4.83 % n/a 8/9/2015 Total $ 20.0 (a) WGL includes WGL Holdings and all subsidiaries other than Washington Gas. (b) Represents face amount. (c) Floating rate per annum that will be determined from time to time based on parameters set forth in the credit agreement. Effective cost reflects current rate. (d) The estimated effective cost of the issued notes, including consideration of issuance fees and hedge costs.
Long Term Debt Maturities	Maturities of long-term debt for each of the next five fiscal years and thereafter as of September 30, 2016 are summarized in the following table. Long-Term Debt Maturities (a) (In millions) WGL (b) Washington Gas Total 2017 $ — $ — $ — 2018 250.0 — 250.0 2019 — 50.0 50.0 2020 100.0 50.0 150.0 2021 — — — Thereafter 150.0 846.0 996.0 Total $ 500.0 $ 946.0 $ 1,446.0 Less: current maturities — — — Total non-current $ 500.0 $ 946.0 $ 1,446.0 (a) Excludes unamortized discounts of $ 1.6 million and $0.1 million at September 30, 2016 , for WGL and Washington Gas, respectively. (b) WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Sep. 30, 2016
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock Reserves	At September 30, 2016 , there were 8,252,975 authorized, but unissued, shares of common stock reserved under the following plans: Common Stock Reserves Reserve for: Number of Shares Omnibus incentive compensation plan (a) 2,790,712 Dividend reinvestment and common stock purchase plan 2,775,341 Employee savings plans 637,196 Directors’ stock compensation plan 68,694 ATM program 1,981,032 Total common stock reserves 8,252,975 (a) In March 2007, WGL adopted a shareholder-approved Omnibus Incentive Compensation Plan to replace on a prospective basis the 1999 Incentive Compensation Plan. In December 2015, the Board of Directors approved the 2016 Omnibus Incentive Compensation Plan that became effective upon shareholder approval at WGL's Annual Meeting of Stockholders on March 1, 2016. The plan was included as an exhibit to WGL's proxy statement under cover of Form 14A filed on January 20, 2016. Following shareholder approval of the 2016 Omnibus Incentive Compensation Plan, WGL will no longer make equity grants under the 2007 Omnibus Incentive Compensation Plan (but shares issued pursuant to outstanding grants under the 2007 plan will be issued pursuant to that plan). Refer to Note 11—Stock-Based Compensation for a discussion regarding our stock-based compensation plans.

Preferred Stock (Tables)

Preferred Stock (Tables)	12 Months Ended
	Sep. 30, 2016
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock Table	The following table presents this information, as well as call prices for each preferred stock series outstanding. Preferred Stock Preferred Liquidation Preference Series Shares Per Share Call Price Outstanding Outstanding Involuntary Voluntary Per Share $4.80 150,000 $100 $101 $101 $4.25 70,600 $100 $105 $105 $5.00 60,000 $100 $102 $102

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings per Share	Basic and Diluted EPS Years Ended September 30, (In thousands, except per share data) 2016 2015 2014 Basic earnings per average common share: Net income applicable to common stock $ 167,594 $ 131,259 $ 105,940 Average common shares outstanding—basic 50,369 49,794 51,759 Basic earnings per average common share $ 3.33 $ 2.64 $ 2.05 Diluted earnings per average common share: Net income applicable to common stock $ 167,594 $ 131,259 $ 105,940 Average common shares outstanding—basic 50,369 49,794 51,759 Stock-based compensation plans 195 266 11 Total average common shares outstanding—diluted 50,564 50,060 51,770 Diluted earnings per average common share $ 3.31 $ 2.62 $ 2.05

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2016
Income Taxes [Line Items]
Components of Income Tax Expense	The tables below provide the following for WGL and Washington Gas: (i) the components of income tax expense; (ii) a reconciliation between the statutory federal income tax rate and the effective income tax rate and (iii) the components of accumulated deferred income tax assets and liabilities at September 30, 2016 and 2015 . WGL Holdings, Inc. Components of Income Tax Expense Years Ended September 30, (In thousands) 2016 2015 2014 INCOME TAX EXPENSE Current: Federal $ (57,690 ) $ (18,639 ) $ 29,976 State (1,983 ) 2,977 5,149 Total current (59,673 ) (15,662 ) 35,125 Deferred: Federal Accelerated depreciation 93,175 71,529 35,747 Other 49,638 17,726 (18,014 ) State Accelerated depreciation 12,993 13,739 9,822 Other 8,073 1,411 (1,760 ) Total deferred 163,879 104,405 25,795 Amortization of investment tax credits (6,132 ) (4,939 ) (3,666 ) Total income tax expense $ 98,074 $ 83,804 $ 57,254
Reconciliation Between the Statutory Federal Income Tax Rate and Effective Tax Rate	WGL Holdings, Inc. Reconciliation Between the Statutory Federal Income Tax Rate and Effective Tax Rate Years Ended September 30, ($ In thousands) 2016 2015 2014 Income taxes at statutory federal income tax rate $ 93,253 35.00 % $ 75,760 35.00 % $ 57,580 35.00 % Increase (decrease) in income taxes resulting from: Accelerated depreciation less amount deferred 908 0.34 1,187 0.55 1,875 1.14 Amortization of investment tax credits (6,132 ) (2.30 ) (4,939 ) (2.28 ) (3,666 ) (2.23 ) Cost of removal (3,722 ) (1.40 ) (2,721 ) (1.26 ) (4,902 ) (2.98 ) State income taxes-net of federal benefit 12,969 4.87 11,109 5.13 8,734 5.31 Medicare Part D adjustment — — — — (3,621 ) (2.20 ) ASDHI impairment — — 1,969 0.91 — — Other items-net 798 0.30 1,439 0.66 1,254 0.76 Total income tax expense and effective tax rate $ 98,074 36.81 % $ 83,804 38.71 % $ 57,254 34.80 %
Components of Deferred Income Tax Assets (Liabilities)	WGL Holdings, Inc. Components of Accumulated Deferred Income Tax Assets (Liabilities) (In thousands) 2016 2015 Deferred income tax assets: Pensions $ 60,685 $ 44,468 Uncollectible accounts 12,441 10,389 Inventory overheads 5,046 5,873 Employee compensation and benefits 49,443 57,230 Derivatives 58,203 43,891 Deferred gas costs — 2,406 Solar grant/investment tax credit 64,149 53,067 Tax credit carry forward 118,980 55,040 Net operating loss 27,741 — Other (a) 1,075 5,640 Total assets 397,763 278,004 Deferred income tax liabilities: Other post-retirement benefits 69,899 54,860 Accelerated depreciation and other plant related items 949,807 794,099 Losses/gains on reacquired debt 1,155 1,292 Income taxes recoverable through future rates 71,352 68,245 Deferred gas costs 1,696 815 Partnership basis differences 27,532 29,468 Valuation allowances 2,188 2,188 Total liabilities 1,123,629 950,967 Net accumulated deferred income tax assets (liabilities) $ (725,866 ) $ (672,963 ) (a) Includes $ 0.897 million in deferred income tax assets reported in "Deferred charges and other assets" on the consolidated balance sheet
Unrecognized Tax Benefits	The following table summarizes the change in unrecognized tax benefits during fiscal year 2016 , 2015 , 2014 and our total unrecognized tax benefits at September 30, under the provisions of ASC Topic 740, Income Taxes: Unrecognized Tax Benefits (In thousands) 2016 2015 2014 Total unrecognized tax benefits, October 1, $ 38,627 $ 32,613 $ 25,051 Increases in tax positions relating to current year 10,645 12,848 10,512 Decreases in tax positions relating to prior year (6,989 ) (6,834 ) (2,950 ) Total unrecognized tax benefits, September 30, $ 42,283 $ 38,627 $ 32,613
Washington Gas Light Company
Income Taxes [Line Items]
Components of Income Tax Expense	Washington Gas Light Company Components of Income Tax Expense Years Ended September 30, (In thousands) 2016 2015 2014 INCOME TAX EXPENSE Current: Federal $ (48,064 ) $ (5,305 ) $ 37,098 State (2,957 ) 907 4,262 Total current (51,021 ) (4,398 ) 41,360 Deferred: Federal Accelerated depreciation 93,385 71,046 34,833 Other 13,826 (6,619 ) (30,523 ) State Accelerated depreciation 13,081 13,701 9,540 Other 3,190 (1,507 ) (6,800 ) Total deferred 123,482 76,621 7,050 Amortization of investment tax credits (795 ) (832 ) (876 ) Total income tax expense $ 71,666 $ 71,391 $ 47,534
Reconciliation Between the Statutory Federal Income Tax Rate and Effective Tax Rate	Washington Gas Light Company Reconciliation Between the Statutory Federal Income Tax Rate and Effective Tax Rate Years Ended September 30, ($ In thousands) 2016 2015 2014 Income taxes at statutory federal income tax rate $ 64,673 35.00 % $ 63,024 35.00 % $ 51,050 35.00 % Increase (decrease) in income taxes resulting from: Accelerated depreciation less amount deferred 1,936 1.05 2,108 1.17 1,875 1.29 Amortization of investment tax credits (795 ) (0.43 ) (832 ) (0.46 ) (876 ) (0.60 ) Cost of removal (3,722 ) (2.01 ) (2,721 ) (1.51 ) (4,902 ) (3.36 ) State income taxes-net of federal benefit 8,310 4.50 8,986 4.99 6,711 4.60 Consolidated tax sharing allocation 1,073 0.58 (533 ) (0.30 ) (2,862 ) (1.96 ) Medicare Part D adjustment — — — — (3,621 ) (2.48 ) Other items-net 191 0.10 1,359 0.76 159 0.09 Total income tax expense and effective tax rate $ 71,666 38.79 % $ 71,391 39.65 % $ 47,534 32.58 %
Components of Deferred Income Tax Assets (Liabilities)	Washington Gas Light Company Components of Accumulated Deferred Income Tax Assets (Liabilities) (In thousands) 2016 2015 Deferred income tax assets: Pensions $ 59,878 $ 43,748 Uncollectible accounts 8,054 7,637 Inventory overheads 5,046 5,873 Employee compensation and benefits 43,755 38,857 Derivatives 27,394 38,887 Deferred gas costs — 2,406 Net operating loss 24,588 — Other — 862 Total assets 168,715 138,270 Deferred income tax liabilities: Other post-retirement benefits 69,520 54,566 Accelerated depreciation and other plant related items 783,919 681,108 Losses/gains on reacquired debt 1,155 1,292 Income taxes recoverable through future rates 71,063 67,953 Deferred gas costs 1,696 815 Other 5,082 1,300 Total liabilities 932,435 807,034 Net accumulated deferred income tax assets (liabilities) $ (763,720 ) $ (668,764 )

Pension and Other Post-Retire41

Pension and Other Post-Retirement Benefit Plans (Tables)	12 Months Ended
	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Post Retirement Benefits	The following table provides certain information about Washington Gas’ post-retirement benefits: Post-Retirement Benefits Health and Life (In millions) Pension Benefits (a) Benefits Year Ended September 30, 2016 2015 2016 2015 Change in projected benefit obligation (b) Benefit obligation at beginning of year $ 947.5 $ 917.1 $ 299.9 $ 343.2 Service cost 14.2 15.5 4.6 7.1 Interest cost 41.3 39.1 13.1 14.7 Change in plan benefits 0.5 0.6 — (26.1 ) Actuarial loss (gain) 110.5 19.2 19.5 (23.7 ) Retiree contributions — — 2.3 2.0 Employer group waiver plan rebates — — 1.2 2.4 Benefits paid (44.7 ) (44.0 ) (16.3 ) (19.7 ) Projected benefit obligation at end of year (b) $ 1,069.3 $ 947.5 $ 324.3 $ 299.9 Change in plan assets Fair value of plan assets at beginning of year $ 780.2 $ 804.7 $ 438.5 $ 439.6 Actual return on plan assets 115.0 19.9 65.1 (0.3 ) Company contributions 1.8 1.8 14.9 16.0 Retiree contributions and employer group waiver plan rebates — — 3.5 3.6 Expenses (2.3 ) (2.2 ) (0.7 ) (0.7 ) Benefits paid (44.7 ) (44.0 ) (16.3 ) (19.7 ) Fair value of plan assets at end of year $ 850.0 $ 780.2 $ 505.0 $ 438.5 Funded status at end of year $ (219.3 ) $ (167.3 ) $ 180.7 $ 138.6 Total amounts recognized on balance sheet Non-current asset $ — $ — $ 180.7 $ 138.6 Current liability (6.3 ) (4.8 ) — — Non-current liability (213.0 ) (162.5 ) — — Total recognized $ (219.3 ) $ (167.3 ) $ 180.7 $ 138.6 (a) The DB SERP and DB Restoration, included in pension benefits in the table above, have no assets. (b) For the Health and Life Benefits, the change in projected benefit obligation represents the accumulated benefit obligation.
Projected and accumulated benefit obligation	The following table provides the projected benefit obligation (PBO) and accumulated benefit (ABO) for the qualified pension plan, DB SERP and DB Restoration at September 30, 2016 and 2015 . Projected and accumulated benefit obligation (In millions) Qualified Pension Plan DB SERP DB Restoration September 30, 2016 2015 2016 2015 2016 2015 Projected benefit obligation $ 1,005.0 $ 892.2 $ 60.4 $ 53.0 $ 3.9 $ 2.3 Accumulated benefit obligation $ 922.3 $ 822.8 $ 56.5 $ 48.7 $ 2.3 $ 1.2
Unrecognized Costs Income Recorded On Balance Sheet	The following table provides amounts recorded to regulatory assets, regulatory liabilities and accumulated other comprehensive loss/(income) at September 30, 2016 and 2015 : Unrecognized Costs/Income Recorded on the Balance Sheet (In millions) Pension Benefits Health and Life Benefits September 30, 2016 2015 2016 2015 Actuarial net loss $ 211.9 $ 190.1 $ 18.1 $ 43.8 Prior service cost (credit) 1.5 1.5 (142.5 ) (160.2 ) Total $ 213.4 $ 191.6 $ (124.4 ) $ (116.4 ) Regulatory asset (liability) (a) $ 193.4 $ 173.9 $ (118.0 ) $ (110.5 ) Pre-tax accumulated other comprehensive loss (gain) (b) 20.0 17.7 (6.4 ) (5.9 ) Total $ 213.4 $ 191.6 $ (124.4 ) $ (116.4 ) (a) The regulatory liability recorded on our balance sheets at September 30, 2016 and 2015 is net of a deferred income tax benefit of $ 4.1 million and $6.1 million , respectively. (b) The total amount of accumulated other comprehensive loss recorded on our balance sheets at September 30, 2016 and 2015 is net of an income tax benefit of $5.8 million and $5.1 million , respectively.
Amount Recognized During Current Year	The following table provides amounts that are included in regulatory assets/liabilities and accumulated other comprehensive loss associated with our unrecognized pension and other post-retirement benefit costs that were recognized as components of net periodic benefit cost during fiscal year 2016 . Amounts Recognized During Fiscal Year 2016 Regulatory assets/liabilities Accumulated other comprehensive loss (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Actuarial net loss (income) $ 15.3 $ 1.2 $ 1.5 $ 0.1 Prior service cost (credit) 0.2 (16.8 ) 0.1 (0.9 ) Total $ 15.5 $ (15.6 ) $ 1.6 $ (0.8 )
Amount Recognized During Next Fiscal Year	The following table provides amounts that are included in regulatory assets/liabilities and accumulated other comprehensive loss associated with our unrecognized pension and other post-retirement benefit costs that are expected to be recognized as components of net periodic benefit cost during fiscal year 2017 . Amounts to be Recognized During Fiscal Year 2017 Regulatory assets/liabilities Accumulated other comprehensive loss (In millions) Pension Benefits Health and Life Benefits Pension Benefits Health and Life Benefits Actuarial net loss $ 19.9 $ 0.7 $ 2.1 $ — Prior service cost (credit) 0.2 (16.7 ) 0.1 (0.9 ) Total $ 20.1 $ (16.0 ) $ 2.2 $ (0.9 )
Components of Net Periodic Benefit Costs (Income)	The components of the net periodic benefit costs (income) for fiscal years ended September 30, 2016 , 2015 and 2014 related to pension and other post-retirement benefits were as follows: Components of Net Periodic Benefit Costs (Income) (In millions) Pension Benefits Health and Life Benefits Year Ended September 30, 2016 2015 2014 2016 2015 2014 Service cost $ 14.2 $ 15.5 $ 14.0 $ 4.6 $ 7.1 $ 7.6 Interest cost 41.3 39.1 40.4 13.1 14.7 18.7 Expected return on plan assets (40.9 ) (44.6 ) (41.0 ) (20.4 ) (20.8 ) (19.3 ) Recognized prior service cost (credit) 0.3 0.3 0.3 (17.7 ) (15.3 ) (9.6 ) Recognized actuarial loss 16.9 18.7 16.8 1.2 4.4 5.0 Net periodic benefit cost 31.8 29.0 30.5 (19.2 ) (9.9 ) 2.4 Amount allocated to construction projects (5.6 ) (4.6 ) (4.3 ) 4.1 1.9 (0.4 ) Amount deferred as regulatory asset (liability)-net 7.1 7.1 7.0 (0.2 ) (0.2 ) (2.3 ) Amount charged (credited) to expense $ 33.3 $ 31.5 $ 33.2 $ (15.3 ) $ (8.2 ) $ (0.3 )
Benefit Obligations Assumptions/Net Periodic Benefits Assumptions	The weighted average assumptions used to determine net periodic benefit obligations and net periodic benefit costs were as follows: Benefit Obligations Assumptions Pension Benefits Health and Life Benefits September 30, 2016 2015 2016 2015 Discount rate (a) 3.40%-3.70% 4.10%-4.50% 3.70 % 4.50 % Rate of compensation increase 3.50%-4.10% 3.50%-4.10% 4.10 % 4.10 % (a) The decrease in the discount rate in fiscal year 2016 compared to prior years primarily reflects the decrease in long-term interest rates. Net Periodic Benefit Cost Assumptions Pension Benefits Health and Life Benefits Years Ended September 30, 2016 2015 2014 2016 2015 2014 Discount rate (a) 4.10%-4.50% 4.00%-4.40% 4.50%-5.00% 4.50 % 4.40 % 4.60%-5.10% Expected long-term return on plan assets (b) 6.00 % 6.75 % 6.50 % 5.75 % 6.25 % 6.25 % Rate of compensation increase (c) 3.50%-4.10% 3.50%-4.10% 3.85%-5.15% 4.10 % 4.10 % 3.85 % (a) The changes in the discount rates over the last three fiscal years primarily reflect the changes in long-term interest rates. (b) For health and life benefits, the expected returns for certain funds may be lower due to certain portions of income that are subject to an assumed income tax rate of 45.3% . (c) The changes in the rate of compensation reflects the best estimates of actual future compensation levels including consideration of general price levels, productivity, seniority, promotion, and other factors such as inflation rates.
Healthcare Trends	Healthcare Trend (In millions) One Percentage-Point Increase One Percentage-Point Decrease Increase (decrease) total service and interest cost components $ 0.6 $ (0.5 ) Increase (decrease) post-retirement benefit obligation $ 5.9 $ (5.3 )
Valuation Methods Level 3 assets	The following table summarizes the changes in the fair value of the Level 3 assets for the fiscal years ended 2016 and 2015 : (In millions) Years Ended September 30, 2016 2015 Balance, beginning of year $ 27.7 $ 23.8 Actual return on plan assets: Assets still held at year end 0.2 3.9 Assets sold during the year 1.9 — Purchase, sales and settlements $ (7.4 ) $ — Balance, end of year $ 22.4 $ 27.7
Expected Benefit Payments	Expected benefit payments, including benefits attributable to estimated future employee service, which are expected to be paid over the next ten years are as follows: Expected Benefit Payments (In millions) Pension Benefits Health and Life Benefits 2017 $ 51.8 $ 17.0 2018 52.6 16.5 2019 54.2 16.8 2020 55.3 16.8 2021 58.1 16.8 2022—2026 287.6 84.1
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB Plan Assets	The following tables present the fair value of the pension plan assets and health and life insurance plan assets by asset category as of September 30, 2016 and 2015 : Pension Plan Assets % of ($ In millions) Level 1 Level 2 Level 3 Total Total At September 30, 2016 Cash and cash equivalents $ 0.3 $ — $ — $ 0.3 — % Equity securities U.S. Small Cap 36.5 — — 36.5 4.3 Preferred Securities — 1.1 — 1.1 0.1 Fixed income securities U.S. Treasuries — 135.4 — 135.4 15.9 U.S. Corporate Debt — 200.6 — 200.6 23.6 U.S. Agency Obligations and Government Sponsored Entities — 18.2 — 18.2 2.1 Asset-Backed Securities — 1.5 — 1.5 0.3 Municipalities — 13.7 — 13.7 1.6 Non-U.S. Corporate Debt — 45.5 — 45.5 5.4 Other (a) — 6.8 — 6.8 0.8 Mutual Funds (b) 34.0 — — 34.0 4.0 Commingled Funds and Pooled Separate Accounts (c) — 302.3 22.4 324.7 38.2 Private Equity/Limited Partnerships (d) — 31.8 — 31.8 3.7 Derivatives (e) — 1.2 — 1.2 0.2 Total fair value of plan investments $ 70.8 $ 758.1 $ 22.4 $ 851.3 100.2 % Net payable (f) (1.3 ) (0.2 ) Total plan assets at fair value $ 850.0 100.0 % Pension Plan Assets % of ($ In millions) Level 1 Level 2 Level 3 Total Total At September 30, 2015 Cash and cash equivalents $ 0.8 $ — $ — $ 0.8 0.1 % Equity securities U.S. Small Cap 28.7 — — 28.7 3.7 Preferred Securities — 0.1 — 0.1 — Fixed income securities U.S. Treasuries — 101.3 — 101.3 13.0 U.S. Corporate Debt — 204.6 — 204.6 26.2 U.S. Agency Obligations and Government Sponsored Entities — 23.9 — 23.9 3.1 Asset-Backed Securities and Collateralized Mortgage Obligations — 1.7 — 1.7 0.2 Municipalities — 14.0 — 14.0 1.8 Non-U.S. Corporate Debt — 37.1 — 37.1 4.8 Repurchase Agreements (g) — 5.3 — 5.3 0.7 Other (a) — 4.7 — 4.7 0.6 Mutual Funds (b) — 29.3 — 29.3 3.7 Commingled Funds and Pooled Separate Accounts (c) — 274.8 27.7 302.5 38.7 Private Equity/Limited Partnerships (d) — 28.0 — 28.0 3.6 Derivatives (e) — (0.1 ) — (0.1 ) — Total fair value of plan investments $ 29.5 $ 724.7 $ 27.7 $ 781.9 100.2 % Net payable (f) (1.7 ) (0.2 ) Total plan assets at fair value $ 780.2 100.0 % (a) This category primarily includes non-U.S. government bonds as of September 30, 2016 and Yankee bonds and non-U.S. government bonds as of September 30, 2015. (b) At September 30, 2016 and September 30, 2015 the investment in a mutual fund consisted primarily of common stock of non-U.S. based companies. (c) At September 30, 2016, investments in commingled funds and a pooled separate account consisted primarily of 85% common stock of large-cap U.S companies; 14% income producing properties located in the United States; and 1% short-term money market investments. As of September 30, 2015, investments in commingled funds and a pooled separate accounts consisted primarily of 80% common stock of large-cap U.S companies; 18% income producing properties located in the United States; and 2% short-term money market investments. (d) At September 30, 2016 and 2015, an investments in a private equity/limited partnership consisted of common stock of international companies. (e) At September 30, 2016 and 2015, this category included a combination of long-term U.S. Treasury interest rate future contracts, currency forwards, a currency option interest rate swaps, and put and call options on both interest rate swaps and credit default swap index products. (f) At September 30, 2016 and September 30, 2015
Other post-retirement benefits
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB Plan Assets	Healthcare and Life Insurance Plan Assets % of ($ In millions) Level 1 Level 2 Level 3 Total Total At September 30, 2016 Cash and Cash Equivalents $ 2.2 $ — $ — $ 2.2 0.4 % Fixed Income Securities U.S Agency Obligations — 1.7 — 1.7 0.3 U.S. Treasuries — 33.3 — 33.3 6.6 U.S. Corporate Debt — 38.2 — 38.2 7.6 Municipalities — 4.1 — 4.1 0.8 Non-U.S. Corporate Debt — 6.4 — 6.4 1.3 Other (a) — 2.8 — 2.8 0.6 Commingled Funds (b) — 415.6 — 415.6 82.3 Total fair value of plan investments $ 2.2 $ 502.1 $ — $ 504.3 99.9 % Net receivable (d) 0.7 0.1 Total plan assets at fair value $ 505.0 100.0 % At September 30, 2015 Cash and Cash Equivalents $ — $ — $ — $ — — % Mutual Funds (c) 1.9 — — 1.9 0.4 Fixed Income Securities U.S Agency Obligations — 1.8 — 1.8 0.4 U.S. Treasuries — 27.7 — 27.7 6.3 U.S. Corporate Debt — 33.5 — 33.5 7.7 Municipalities — 4.0 — 4.0 0.9 Non-U.S. Corporate Debt — 4.9 — 4.9 1.1 Other (a) — 4.3 — 4.3 1.0 Commingled Funds (b) — 359.7 — 359.7 82.0 Total fair value of plan investments $ 1.9 $ 435.9 $ — $ 437.8 99.8 % Net receivable (d) 0.7 0.2 Total plan assets at fair value $ 438.5 100.0 % (a) At September 30, 2016, this category consisted primarily of non-U.S government bonds. At September 30, 2015, this category consisted primarily of non-U.S. government bonds and Yankee bonds. (b) At September 30, 2016, investments held by commingled funds in which the plan invests consisted primarily of 68% of common stock of large-cap U.S. companies, 12% of U.S. Government fixed income securities and 20% of corporate bonds. At September 30, 2015, investments held by commingled funds in which the plan invests consisted primarily of 68% of common stock of large-cap U.S. companies, 16% of U.S. Government fixed income securities and 16% of corporate bonds. (c) At September 30, 2015, investment in mutual funds consisted of a short-term money market fund valued at $1.00 per share.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Performance Share Activity	The following table summarizes information regarding performance share activity during the fiscal year ended September 30, 2016 . Performance Share Activity Year Ended September 30, 2016 Number of Shares (a) Weighted Average Grant- Date Fair Value Non-vested and outstanding, beginning of year 304,089 $ 44.49 Granted 89,328 62.49 Vested (95,871 ) 43.29 Cancelled/forfeited (5,367 ) 50.63 Non-vested and outstanding, end of year 292,179 $ 50.28 (a) The number of common shares issued related to 248,394 non-vested performance shares outstanding at year-end may range from zero to 200 percent of this number based on our satisfaction of the market condition for total shareholder return relative to a selected peer group of companies. For 43,785 non-vested performance shares outstanding at year-end, the number of common shares issued may range from zero to 100% of this number based on our satisfaction of the performance condition for non-GAAP diluted earnings per share as compared to dividends paid per share.
Performance Share Fair Value Assumptions	: Fair Value Assumptions Years Ended September 30, 2016 2015 2014 Expected stock-price volatility (a) 19.10 % 18.30 % 19.10 % Dividend yield (b) — 4.18 % 3.93 % Weighted average grant-date fair value $ 67.30 $ 44.44 $ 42.88
Performance Unit Activity	The following table summarizes information regarding performance unit activity during the fiscal year ended September 30, 2016 . Performance Unit Activity Year Ended September 30, 2016 Number of Units (a) Non-vested and outstanding, beginning of year 12,685,633 Granted 5,152,000 Vested (3,858,799 ) Cancelled/forfeited (254,116 ) Non-vested and outstanding, end of year 13,724,718
Performance Units Fair Value Assumptions	the fair value that is accrued as compensation expense at the end of each period equals the percentage of the requisite service that has been rendered at that date. Consequently, fluctuations in earnings may result, that do not occur under the accounting requirements for our performance shares. The fair value of each performance unit that vests based on the satisfaction of a performance condition is $1.00. The amount of total compensation cost to be recognized for these performance units is a function of this fair value and the number of awards vested as a result of the performance condition being met and the requisite service provided. The fair value of each performance unit that vests based on the satisfaction of a market condition is estimated using a Monte Carlo simulation model and the following assumptions: Fair Value Assumptions September 30, 2016 10/1/2015 Grant 10/1/2014 Grant Expected stock-price volatility (a) 20.80 % 20.90 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Sep. 30, 2016
Commitments and Contingencies [Line Items]
Schedule of Future Minimum Rental Payments for Operating Leases	Minimum future rental payments under operating leases over the next five years and thereafter are as follows: Minimum Payments Under Operating Leases (In millions) 2017 $ 7.5 2018 7.5 2019 3.9 2020 3.7 2021 3.4 Thereafter 27.8 Total $ 53.8
Washington Gas Light Company
Commitments and Contingencies [Line Items]
Long-term Purchase Commitment	The following table summarizes the minimum contractual payments that Washington Gas will make under its pipeline transportation, storage and peaking contracts, as well as minimum contractual payments to purchase natural gas at prices based on market conditions during the next five fiscal years and thereafter. Washington Gas Contract Minimums (In millions) Pipeline Contracts (a) Gas Purchase Commitments (b) 2017 $ 218.8 $ 467.8 2018 217.8 404.5 2019 232.3 357.7 2020 231.4 359.2 2021 222.7 385.3 Thereafter 1,261.0 3,897.9 Total $ 2,384.0 $ 5,872.4 (a) Represents minimum payments for natural gas transportation, storage and peaking contracts that have expiration dates through fiscal year 2034. (b) Includes known and reasonably likely commitments to purchase natural gas. Cost estimates are based on forward market prices at September 30, 2016 .
Non Utility
Commitments and Contingencies [Line Items]
Long-term Purchase Commitment	The following table summarizes the minimum commitments and contractual obligations of WGL Energy Services and WGL Midstream for the next five fiscal years and thereafter. Contract Minimums WGL Energy Services WGL Midstream (In millions) Gas Purchase Commitments (a) Pipeline Contracts (b) Electric Purchase Commitments (c) Gas Purchase Commitments (d) Pipeline Contracts (b) Total 2017 $ 148.8 $ 3.2 $ 413.1 $ 464.5 $ 25.0 $ 1,054.6 2018 40.1 1.5 179.6 1,077.6 19.5 1,318.3 2019 16.7 0.8 78.2 1,512.2 63.1 1,671.0 2020 7.5 0.5 30.2 1,641.2 66.7 1,746.1 2021 0.4 0.4 1.7 1,622.4 65.5 1,690.4 Thereafter — 0.8 0.9 27,780.0 972.0 28,753.7 Total $ 213.5 $ 7.2 $ 703.7 $ 34,097.9 $ 1,211.8 $ 36,234.1 (a) Represents fixed price commitments with city gate equivalent deliveries. (b) Represents minimum payments for natural gas transportation and storage contracts that have expiration dates through fiscal year 2044. (c) Represents electric purchase commitments that are based on existing fixed price and fixed volume contracts. Includes $18.3 million of commitments related to renewable energy credits. (d) Includes known and reasonably likely commitments to purchase natural gas. Cost estimates are based on forward market prices as of September 30, 2016 . Certain of our gas purchase agreements have optionality, which may cause increases in these commitments.

Derivative and Weather Relate44

Derivative and Weather Related Instruments (Tables)	12 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Absolute Notional Amounts of Open Positions on Derivative Instruments	At September 30, 2016 and 2015 , respectively, the absolute notional amounts of our derivatives are as follows: Absolute Notional Amounts of Open Positions on Derivative Instruments Derivative transactions WGL Holdings Washington Gas September 30, 2016 Notional Amounts Natural Gas (In millions of therms) Asset optimization & trading 21,084.5 12,725.0 Retail sales 50.2 — Other risk-management activities 1,789.0 1,309.0 Electricity (In millions of kWhs) Retail sales 4,377.5 — Other risk-management activities (a) 21,070.4 — Interest Rate Swaps (In millions of dollars) $ 250.0 $ — September 30, 2015 Natural Gas (In millions of therms) Asset optimization & trading 20,829.2 13,316.7 Retail sales 52.2 — Other risk-management activities 1,811.7 1,381.8 Electricity (In millions of kWhs) Retail sales 4,292.7 — Other risk-management activities (a) 19,965.7 — Interest Rate Swaps (In millions of dollars) $ 125.0 $ — (a) Comprised primarily of financial swaps, financial transmission rights and physical forward purchases.
Balance Sheet Classification of Derivative Instruments	The following tables present the balance sheet classification for all derivative instruments as of September 30, 2016 and 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 September 30, 2016 Gross Derivative Assets Gross Derivative Liabilities Gross Derivative Assets Gross Derivative Liabilities Netting of Collateral Total (a) Current Assets—Derivatives $ 24.0 $ (5.5 ) $ — $ — $ — $ 18.5 Deferred Charges and Other Assets—Derivatives 55.6 (0.6 ) — — — 55.0 Current Liabilities—Derivatives 18.3 (113.2 ) — — 12.6 (82.3 ) Deferred Credits—Derivatives 6.4 (279.3 ) 0.2 (43.1 ) 11.6 (304.2 ) Total $ 104.3 $ (398.6 ) $ 0.2 $ (43.1 ) $ 24.2 $ (313.0 ) 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 September 30, 2016 Gross Gross Netting of Total (a) Current Assets—Derivatives $ 11.7 $ (4.4 ) $ — $ 7.3 Deferred Charges and Other Assets—Derivatives 26.2 (0.6 ) — 25.6 Current Liabilities—Derivatives 1.9 (60.2 ) — (58.3 ) Deferred Credits—Derivatives — (232.0 ) — (232.0 ) Total $ 39.8 $ (297.2 ) $ — $ (257.4 ) 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 September 30, 2016 or 2015 .
Gains and (Losses) on Derivative Instruments	The following tables present all gains and losses associated with derivative instruments for the years ended September 30, 2016 , 2015 and 2014 . Gains and Losses on Derivative Instruments (In millions) WGL Holdings, Inc. Washington Gas Fiscal Year Ended September 30, 2016 2015 2014 2016 2015 2014 Recorded to income Operating revenues—non-utility $ 5.8 $ 71.3 $ (47.9 ) $ — $ — $ — Utility cost of gas 12.1 (14.5 ) (87.3 ) 12.1 (14.5 ) (87.3 ) Non-utility cost of energy-related sales 33.5 (43.7 ) 36.2 — — — Other income-net — — (1.1 ) — — — Interest expense (0.2 ) (0.6 ) (0.2 ) — — — Recorded to regulatory assets Gas costs 13.9 (18.4 ) (143.3 ) 13.9 (18.4 ) (143.3 ) Other (a) (7.3 ) — 0.2 (7.3 ) — 0.2 Recorded to other comprehensive income (b) (39.3 ) (11.3 ) (1.5 ) — — — Total $ 18.5 $ (17.2 ) $ (244.9 ) $ 18.7 $ (32.9 ) $ (230.4 ) (a) Represents the settlement of Washington Gas' forward starting interest rate swap in September 2016. (b) Represents the effective portion of our cash flow hedges.
Collateral Not Offset Against Derivative Assets and Liabilities	The table below presents collateral positions at September 30, 2016 and 2015 , respectively. Collateral Not Offset Against Derivative Assets and Liabilities (In millions) September 30, 2016 Collateral deposits posted with counterparties Cash collateral held representing an obligation Washington Gas $ 4.3 $ 0.1 WGL Energy Services 9.1 — WGL Midstream 18.5 5.4 September 30, 2015 Washington Gas $ 3.5 $ 3.8 WGL Energy Services 12.4 — WGL Midstream 3.5 0.4
Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features	The following table shows the aggregate fair value of all derivative instruments with credit-related contingent features that are in a liability position, as well as the maximum amount of collateral that would be required if the most intrusive credit-risk-related contingent features underlying these agreements were triggered on September 30, 2016 and 2015 , respectively. Potential Collateral Requirements for Derivative Liabilities with Credit-Risk-Contingent Features (In millions) WGL Holdings, Inc. Washington Gas September 30, 2016 Derivative liabilities with credit-risk-contingent features $ 53.9 $ 11.3 Maximum potential collateral requirements 41.4 11.3 September 30, 2015 Derivative liabilities with credit-risk-contingent features $ 61.7 $ 18.9 Maximum potential collateral requirements 54.6 18.8

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2016
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 years ended September 30, 2016 and 2015 , respectively. Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs WGL Holdings Inc. Washington Gas Light Company (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Warrants Total Total - Natural Gas Fiscal Year Ended September 30, 2016 Balance at October 1, 2015 $ (309.7 ) $ (16.0 ) $ — $ (325.7 ) $ (281.1 ) Realized and unrealized gains (losses) Recorded to income 18.3 (21.4 ) — (3.1 ) 4.0 Recorded to regulatory assets—gas costs 4.2 — — 4.2 4.2 Transfers into Level 3 (0.8 ) — — (0.8 ) (0.2 ) Transfers out of Level 3 8.9 — — 8.9 9.0 Purchases — (2.4 ) — (2.4 ) — Settlements 15.0 30.7 — 45.7 12.5 Balance at September 30, 2016 $ (264.1 ) $ (9.1 ) $ — $ (273.2 ) $ (251.6 ) Fiscal Year Ended September 30, 2015 Balance at October 1, 2014 $ (294.7 ) $ (5.0 ) $ — $ (299.7 ) $ (270.6 ) Realized and unrealized gains (losses) Recorded to income (30.7 ) (32.3 ) — (63.0 ) (25.0 ) Recorded to regulatory assets—gas costs (30.9 ) — — (30.9 ) (30.9 ) Transfers into Level 3 5.4 — — 5.4 5.4 Transfers out of Level 3 3.6 — — 3.6 2.5 Purchases — 10.5 — 10.5 — Settlements 37.6 10.8 — 48.4 37.5 Balance at September 30, 2015 $ (309.7 ) $ (16.0 ) $ — $ (325.7 ) $ (281.1 )
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 September 30, 2016 and 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 ($264.1) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($2.021) - $3.290 Option Model Natural Gas Basis Price (per dekatherm) ($2.105) - $3.310 ($0.1) Annualized Volatility of Spot Market Natural Gas 25.5% - 869.9% Electricity related derivatives ($9.1) Discounted Cash Flow Electricity Congestion Price (per megawatt hour) ($6.199) - $68.700 Washington Gas Light Company Natural gas related derivatives ($251.6) Discounted Cash Flow Natural Gas Basis Price (per dekatherm) ($2.021) - $3.290 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
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 fiscal years ended September 30, 2016 , 2015 and 2014 , respectively, related to fair value measurements using significant Level 3 inputs. Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements WGL Holdings, Inc. Washington Gas Light Company (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Warrants Total Total - Natural Gas Fiscal Year Ended September 30, 2016 Operating revenues—non-utility $ 8.2 $ (26.5 ) $ — $ (18.3 ) $ — Utility cost of gas 4.0 — — 4.0 4.0 Non-utility cost of energy-related sales 6.1 5.1 — 11.2 — Total $ 18.3 $ (21.4 ) $ — $ (3.1 ) $ 4.0 Fiscal Year Ended September 30, 2015 Operating revenues—non-utility $ (5.7 ) $ 19.9 $ — $ 14.2 $ — Utility cost of gas (25.0 ) — — (25.0 ) (25.0 ) Non-utility cost of energy-related sales — (52.2 ) — (52.2 ) — Total $ (30.7 ) $ (32.3 ) $ — $ (63.0 ) $ (25.0 ) Fiscal Year Ended September 30, 2014 Operating revenues—non-utility $ (2.3 ) $ (22.1 ) $ — $ (24.4 ) $ — Utility cost of gas (69.4 ) — — (69.4 ) (69.4 ) Other income-net — — (1.1 ) (1.1 ) — Non-utility cost of energy-related sales (0.9 ) 16.4 — 15.5 — Total $ (72.6 ) $ (5.7 ) $ (1.1 ) $ (79.4 ) $ (69.4 )
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 fiscal years ended September 30, 2016 , 2015 and 2014 , respectively: Unrealized Gains (Losses) Recorded for Level 3 Measurements WGL Holdings, Inc. Washington Gas Light Company (In millions) Natural Gas Related Derivatives Electricity Related Derivatives Warrants Total Total - Natural Gas Fiscal Year Ended September 30, 2016 Recorded to income Operating revenues—non-utility $ 9.9 $ (2.3 ) $ — $ 7.6 $ — Utility cost of gas 0.3 — — 0.3 0.3 Non-utility cost of energy-related sales (0.4 ) 13.2 — 12.8 — Recorded to regulatory assets—gas costs (2.6 ) — — (2.6 ) (2.6 ) Total $ 7.2 $ 10.9 $ — $ 18.1 $ (2.3 ) Fiscal Year Ended September 30, 2015 Recorded to income Operating revenues—non-utility $ (2.2 ) $ 25.1 $ — $ 22.9 $ — Utility cost of gas (15.8 ) — — (15.8 ) (15.8 ) Non-utility cost of energy-related sales (1.7 ) (41.7 ) — (43.4 ) — Recorded to regulatory assets—gas costs (20.9 ) — — (20.9 ) (20.9 ) Total $ (40.6 ) $ (16.6 ) $ — $ (57.2 ) $ (36.7 ) Fiscal Year Ended September 30, 2014 Recorded to income Operating revenues—non-utility $ (5.0 ) $ (33.8 ) $ — $ (38.8 ) $ — Utility cost of gas (60.6 ) — — (60.6 ) (60.6 ) Non-utility cost of energy-related sales 3.7 30.0 — 33.7 — Other income-net — — (1.1 ) (1.1 ) — Recorded to regulatory assets—gas costs (109.9 ) — — (109.9 ) (109.9 ) Total $ (171.8 ) $ (3.8 ) $ (1.1 ) $ (176.7 ) $ (170.5 )
WGL
Fair Value Measurements Under the Fair Value Hierarchy	The following tables set forth financial instruments recorded at fair value as of September 30, 2016 and 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 September 30, 2016 Assets Natural gas related derivatives $ — $ 28.8 $ 54.0 $ 82.8 Electricity related derivatives — 0.6 20.9 21.5 Interest rate derivatives — 0.2 — 0.2 Total Assets $ — $ 29.6 $ 74.9 $ 104.5 Liabilities Natural gas related derivatives $ — $ (46.7 ) $ (318.2 ) $ (364.9 ) Electricity related derivatives — (3.8 ) (29.9 ) (33.7 ) Interest rate derivatives — (43.1 ) — (43.1 ) Total Liabilities $ — $ (93.6 ) $ (348.1 ) $ (441.7 ) 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 )
Fair Value of Financial Instruments	The following table presents the carrying amounts and estimated fair values of our financial instruments at September 30, 2016 and 2015 . WGL Holdings, Inc. Fair Value of Financial Instruments September 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 10.6 $ 10.6 $ 11.0 $ 11.0 Other short-term investments (a) $ 1.4 $ 1.4 $ 0.4 $ 0.4 Commercial paper (b) $ 269.0 $ 269.0 $ 332.0 $ 332.0 Project financing (b) $ 62.4 $ 62.4 $ — $ — Long-term debt (c) $ 1,444.3 $ 1,641.9 $ 944.2 $ 1,057.9
Washington Gas Light Company
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 September 30, 2016 Assets Natural gas related derivatives $ — $ 15.4 $ 24.4 $ 39.8 Total Assets $ — $ 15.4 $ 24.4 $ 39.8 Liabilities Natural gas related derivatives $ — $ (21.2 ) $ (276.0 ) $ (297.2 ) Total Liabilities $ — $ (21.2 ) $ (276.0 ) $ (297.2 ) 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 )
Fair Value of Financial Instruments	Washington Gas Light Company Fair Value of Financial Instruments September 30, 2016 September 30, 2015 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value Money market funds (a) $ 5.0 $ 5.0 $ 4.3 $ 4.3 Other short-term investments (a) $ 1.4 $ 1.4 $ 0.4 $ 0.4 Commercial paper (b) $ 42.0 $ 42.0 $ 89.0 $ 89.0 Project financing (b) $ 62.4 $ 62.4 $ — $ — Long-term debt (c) $ 945.9 $ 1,126.4 $ 695.9 $ 811.9 (a) Balance is located in cash and cash equivalents in the accompanying balance sheets. These amounts may be offset by outstanding checks. (b) Balance is located in notes payable in the accompanying balance sheets. (c) Includes adjustments for current maturities and unamortized discounts, as applicable.

Operating Segment Reporting (Ta

Operating Segment Reporting (Tables)	12 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Operating Segment Financial Information	The following tables present operating segment information for the fiscal years ended September 30, 2016 , 2015 and 2014 . Operating Segment Financial Information (In thousands) Operating Revenues (a) Depreciation and Amortization Equity in Earnings of Unconsolidated Affiliates EBIT Total Assets Capital Expenditures Equity Method Investments Fiscal Year Ended September 30, 2016 Regulated utility $ 1,070,904 $ 116,129 $ — $ 228,219 $ 4,643,830 $ 393,501 $ — Retail energy-marketing 1,238,480 1,154 — 64,968 486,778 8,104 — Commercial energy systems (b) 89,072 15,201 7,620 21,992 885,734 128,780 66,100 Midstream energy services 6,619 107 6,186 7,807 485,099 — 237,391 Other activities — — — (3,184 ) 276,117 — — Eliminations (c) (55,516 ) (25 ) — (504 ) (718,853 ) — — Total consolidated $ 2,349,559 $ 132,566 $ 13,806 $ 319,298 $ 6,058,705 $ 530,385 $ 303,491 Fiscal Year Ended September 30, 2015 Regulated utility $ 1,328,191 $ 110,416 $ — $ 223,977 $ 4,228,813 $ 327,429 $ — Retail energy-marketing 1,306,758 671 — 46,629 463,141 28 — Commercial energy systems 51,813 10,733 2,095 9,688 689,910 136,749 63,521 Midstream energy services 3,191 129 2,623 (2,720 ) 237,839 85 73,363 Other activities — — 750 (9,667 ) 199,061 — — Eliminations (c) (30,123 ) (57 ) — (1,013 ) (557,405 ) — — Total consolidated $ 2,659,830 $ 121,892 $ 5,468 $ 266,894 $ 5,261,359 $ 464,291 $ 136,884 Fiscal Year Ended September 30, 2014 Regulated utility $ 1,443,800 $ 104,064 $ — $ 184,668 $ 3,956,571 $ 286,323 $ — Retail energy-marketing 1,310,279 756 1 14,015 388,651 76 — Commercial energy systems 40,679 6,178 1,953 6,863 521,049 108,363 66,810 Midstream energy services 16,555 124 771 8,412 209,682 — 28,076 Other activities — — 469 (11,539 ) 369,816 — 16 Eliminations (c) (30,366 ) (350 ) — (167 ) (615,934 ) — — Total consolidated $ 2,780,947 $ 110,772 $ 3,194 $ 202,252 $ 4,829,835 $ 394,762 $ 94,902 (a) Operating revenues are reported gross of revenue taxes. Revenue taxes of both the regulated utility and the retail energy-marketing segments include gross receipt taxes. Revenue taxes of the regulated utility segment also include public service commission fees, franchise fees and energy 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) As of August 2016, Commercial energy systems' operating revenues include revenues from non-controlling interest. Commercial energy systems' EBIT is adjusted for the effects of non-controlling interest. (c) Intersegment eliminations include any mark-to market valuations associated with trading activities 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. Fiscal Year Ended September 30, (In thousands) 2016 2015 2014 Total consolidated EBIT $ 319,298 $ 266,894 $ 202,252 Interest expense 52,310 50,511 37,738 Income tax expense 98,074 83,804 57,254 Dividends on Washington Gas Light Company preferred stock 1,320 1,320 1,320 Net income applicable to common stock $ 167,594 $ 131,259 $ 105,940

Other Investment (Tables)

Other Investment (Tables)	12 Months Ended
	Sep. 30, 2016
Other Investments [Abstract]
Minimum Payments Receivable for Direct Financing Leases	Minimum future lease payments receivable under direct financing leases over the next five fiscal years and thereafter are as follows: Minimum Payments Receivable for Direct Financing Leases (In millions) 2017 $ 2.2 2018 2.2 2019 2.1 2020 2.2 2021 2.2 Thereafter 28.5 Total $ 39.4
Location of Investments	The balance sheet location of the investments discussed in this footnote at September 30, 2016 and 2015 are as follows: Solar Investments Pipelines (in millions) Non-consolidated VIE's Consolidated VIE's Non-consolidated VIE's Non-consolidated Non VIE's Total As of September 30, 2016 Assets Investments in unconsolidated affiliates $ 66.1 $ — $ 80.8 $ 156.6 $ 303.5 Property, plant and equipment — 6.5 — — 6.5 Construction in progress — 6.7 — — 6.7 Investments in direct financing leases, capital leases 29.8 — — — 29.8 Accounts receivable 1.1 — — 9.2 (a) 10.3 Total assets $ 97.0 $ 13.2 $ 80.8 $ 165.8 $ 356.8 As of September 30, 2015 Assets Investments in unconsolidated affiliates $ 63.5 $ — $ 30.5 $ 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 $ 100.7 $ — $ 30.5 $ 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 fiscal year September 30, 2016 , 2015 and 2014 are as follows: WGL Holdings, Inc. Income Statement Location of Other Investments Solar Investments Pipelines Other (In millions) Non-consolidated VIE's Consolidated VIE's Non-consolidated VIE's Non-consolidated Non VIE's Non-consolidated VIE's Non-consolidated Non VIE's Total Fiscal Year Ended September 30, 2016 Equity in earnings of unconsolidated affiliates $ 7.6 $ — $ (0.1 ) $ 6.3 $ — $ — $ 13.8 Depreciation and amortization 0.3 — — — — — 0.3 Operations and maintenance 4.1 — — — — — 4.1 Other income (expenses) - net 3.1 — — (0.1 ) — — 3.0 Non-controlling interest — (0.6 ) — — — — (0.6 ) Fiscal Year Ended September 30, 2015 Equity in earnings of unconsolidated affiliates $ 2.1 $ — $ 0.1 $ 2.6 $ 0.7 $ — $ 5.5 Depreciation and amortization 0.3 — — — — — 0.3 Other income - net 3.2 — — — — (5.6 ) (2.4 ) Fiscal Year Ended September 30, 2014 Equity in earnings of unconsolidated affiliates $ 2.0 $ — $ 0.3 $ 1.0 $ (0.1 ) $ — $ 3.2 Depreciation and amortization 0.2 — — — — — 0.2 Other income - net 2.6 — — — — — 2.6

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Receivables and Payables from Associated Companies	Washington Gas Light Company Receivables / Payables from Associated Companies (In millions) September 30, 2016 September 30, 2015 Receivables from Associated Companies $ 13.8 $ 3.2 Payables to Associated Companies $ 65.8 $ 68.6 The following table shows the amounts Washington Gas charged WGL Energy Services for balancing services. Washington Gas - Gas Balancing Service Charges (In millions) Years Ended September 30, 2016 2015 2014 Gas balancing service charge $ 26.8 $ 25.1 $ 26.6

Accumulated Other Comprehensi49

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following tables show the changes in accumulated other comprehensive income (loss) for WGL and Washington Gas by component for the fiscal years ended September 30, 2016 and 2015 . WGL Holdings, Inc. Changes in Accumulated Other Comprehensive Loss by Component September 30, (In thousands) 2016 2015 Beginning Balance $ (14,236 ) $ (7,961 ) Qualified cash flow hedging instruments (a) (39,289 ) (11,309 ) Change in prior service cost (b) (891 ) 696 Amortization of actuarial loss (b) (936 ) (1,195 ) Current-period other comprehensive loss (41,116 ) (11,808 ) Income tax benefit related to other comprehensive loss (16,813 ) (5,533 ) Ending Balance $ (38,539 ) $ (14,236 ) (a) Cash flow hedging instruments represent interest rate swap agreements related to debt issuances. Refer to Note 14—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 10 — Pension and other post-retirement benefit plans for additional details. Washington Gas Light Company Changes in Accumulated Other Comprehensive Loss by Component September 30, (In thousands) 2016 2015 Beginning Balance $ (6,712 ) $ (6,413 ) Change in prior service cost (a) (891 ) 696 Amortization of actuarial loss (a) (936 ) (1,195 ) Current-period other comprehensive income loss (1,827 ) (499 ) Income tax expense benefit related to other comprehensive loss (709 ) (200 ) Ending Balance $ (7,830 ) $ (6,712 ) (a) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 10 — Pension and other post-retirement benefit plans for additional details.

Quarterly Financial Data (Table

Quarterly Financial Data (Tables)	12 Months Ended
	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	All adjustments necessary for a fair presentation have been included in the quarterly information provided below. Due to the seasonal nature of our business, we report substantial variations in operations on a quarterly basis. Quarter Ended (In thousands, except per share data) December 31 ( a) March 31 June 30 ( b) September 30 (c) Fiscal Year 2016 WGL Holdings, Inc. Operating revenues $ 613,384 $ 835,689 $ 440,587 $ 459,899 Operating income (loss) $ 117,509 $ 174,411 $ 13,683 $ (5,307 ) Net income (loss) $ 68,501 $ 106,618 $ 2,355 $ (9,110 ) Net income (loss) applicable to common stock $ 68,171 $ 106,288 $ 2,025 $ (8,890 ) Earnings (loss) per average share of common stock: Basic $ 1.37 $ 2.13 $ 0.04 $ (0.17 ) Diluted $ 1.36 $ 2.11 $ 0.04 $ (0.17 ) Washington Gas Light Company Operating revenues $ 295,246 $ 452,024 $ 187,077 $ 136,557 Operating income (loss) $ 98,977 $ 164,226 $ (20,528 ) $ (14,308 ) Net income (loss) $ 54,612 $ 94,433 $ (18,519 ) $ (17,412 ) Net income (loss) applicable to common stock $ 54,282 $ 94,103 $ (18,849 ) $ (17,742 ) Fiscal Year 2015 WGL Holdings, Inc. Operating revenues $ 749,237 $ 1,001,733 $ 441,173 $ 467,687 Operating income (loss) $ 121,842 $ 142,886 $ (17,567 ) $ 13,612 Net income (loss) $ 64,218 $ 81,785 $ (15,360 ) $ 1,936 Net income (loss) applicable to common stock $ 63,888 $ 81,455 $ (15,690 ) $ 1,606 Earnings (loss) per average share of common stock: Basic $ 1.28 $ 1.64 $ (0.32 ) $ 0.03 Diluted $ 1.28 $ 1.63 $ (0.32 ) $ 0.03 Washington Gas Light Company Operating revenues $ 387,193 $ 615,694 $ 190,345 $ 134,959 Operating income (loss) $ 114,623 $ 129,944 $ (6,729 ) $ (15,454 ) Net income (loss) $ 64,951 $ 74,694 $ (11,424 ) $ (19,543 ) Net income (loss) applicable to common stock $ 64,621 $ 74,364 $ (11,754 ) $ (19,873 ) (a) During the fist quarter of fiscal year 2016, there were no substantial variations in operations. During the first quarter of fiscal year 2015, WGL recorded an impairment charge of $ 5.6 million related to its investment in ASDHI. (b) During the third quarter of fiscal year 2016, WGL recorded an impairment charge of $ 3.0 million related to its investment in direct financing leases from Nextility. During the third quarter of fiscal year 2015, WGL recorded a $ 3.0 million liability for unrecovered government contracting costs under the Small Business Administration Development 8(a) Program and Washington Gas recorded approximately $ 0.5 million in transaction fees related to the sale of its Springfield Operations Center. Refer to Note 1—Accounting Policies of the Notes to Consolidated Financial Statements for further discussion of the impairments and to Note 13— Commitments and Contingencies for further discussion of the Antero Contract. (c) During the fourth quarter of fiscal year 2016, WGL recorded an additional impairment charge of $1.1 million related to its investment in direct financing leases from Nextility and $ 1.7 million in proceeds from an environmental insurance policy. During the fourth quarter of fiscal year 2015, Washington Gas recorded a one-time adjustment of $ 2.4 million as a result of charges associated with a regulatory proceeding. Refer to Note 1—Accounting Policies of the Notes to Consolidated Financial Statements for further discussion of the impairments, to Note 13— Commitments and Contingencies for further discussion of the Antero Contract and WGL Holdings, Inc Results of Operations for further discussion of the net proceeds related to the environmental insurance policy.

Accounting Policies (Narrative)

Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2016USD ($)investmentsubsidiaryCustomers	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Accounting Policies [Table] [Line Items]
Number of subsidiaries | subsidiary	4
Number of customers (more than one million) | Customers	1,000,000
Number of investments that qualify as VIEs | investment	5
Pretax AFUDC Rate	5.51%	4.12%	3.36%
Composite depreciation and amortization rate	2.70%	2.73%	2.77%
PP&E, other percentage	88.70%	91.20%
Impairment loss	$ 4,110	$ 5,625	$ 2,639
Regulated revenue billing cycle	19 days
Duration of cost of gas recovered or refunded	12 months
Gross revenue taxes	$ 73,000	83,500	84,300
Carrying value of reclassified amounts	$ 9,300
VIE, Not Primary Beneficiary
Accounting Policies [Table] [Line Items]
Variable Interest Entity, Number of Investments | investment	4
VIE, Primary Beneficiary
Accounting Policies [Table] [Line Items]
Variable Interest Entity, Number of Investments | investment	1
Leasehold Improvements
Accounting Policies [Table] [Line Items]
Operating lease useful life	15 years
Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Impairment loss	$ 0	0	2,639
Deferred Tax Assets, Net, Current		24,700
WGL Energy Services | Minimum
Accounting Policies [Table] [Line Items]
Indexed or fixed rate customer contracts terms	24 months
WGL Energy Services | Maximum
Accounting Policies [Table] [Line Items]
Indexed or fixed rate customer contracts terms	5 years
Washington Gas Resources
Accounting Policies [Table] [Line Items]
Impairment loss, cost-method investment		5,600
WGL
Accounting Policies [Table] [Line Items]
Impairment loss, cost-method investment		5,600
Lease Impairment	$ 4,100
Deferred Tax Assets, Net, Current		32,800
Natural Gas Customers | WGL Energy Services
Accounting Policies [Table] [Line Items]
Number of customers | Customers	133,000
Abandoned LNG storage project
Accounting Policies [Table] [Line Items]
Impairment loss		1,900
Springfield Operations Center
Accounting Policies [Table] [Line Items]
Impairment loss			$ 800
Springfield Operations Center | Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Proceeds from Sale of Buildings	$ 20,300
Cost of Other Property Operating Expense	$ 500
Impairment loss		$ 800
Firm Customer | Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Percentage of total gas deliveries	70.00%
Interruptible Customers | Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Percentage of total gas deliveries	13.00%
Electric Generation Customers | Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Percentage of total gas deliveries	16.00%
Electricity Customers | WGL Energy Services
Accounting Policies [Table] [Line Items]
Number of customers | Customers	127,400

Accounting Policies - Property,

Accounting Policies - Property, Plant and Equipment at Original Cost (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Accounting Policies [Table] [Line Items]
Total	$ 5,542,916	$ 5,003,910
PP&E, other percentage	88.70%	91.20%
Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Total	$ 4,874,905	$ 4,521,535
WGL
Accounting Policies [Table] [Line Items]
Total	$ 5,543,000	$ 5,003,900
Total regulated and unregulated segments, percentage	100.00%	100.00%
Regulated Utility
Accounting Policies [Table] [Line Items]
Distribution, transmission and storage	$ 4,210,600	$ 3,927,200
General, miscellaneous and intangibles	435,200	424,800
Construction work in progress (CWIP)	273,100	210,400
Total regulated and unregulated segments	$ 4,918,900	$ 4,562,400
Distribution, transmission and storage, percentage	75.90%	78.50%
General, miscellaneous and intangibles percentage	7.90%	8.50%
Construction work in progress (CWIP), percentage	4.90%	4.20%
PP&E, other percentage	88.70%	91.20%
Unregulated Operation [Member]
Accounting Policies [Table] [Line Items]
Total regulated and unregulated segments	$ 624,100	$ 441,500
PP&E, other percentage	11.30%	8.80%

Accounting Policies - Lower-of-

Accounting Policies - Lower-of-Cost or Market Adjustments Pre-Tax Increase (Decrease) to Net Income (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Accounting Policies [Table] [Line Items]
Lower of cost or market adjustment	$ (22.8)	$ (3.2)
Operating Revenues Non Utility | WGL
Accounting Policies [Table] [Line Items]
Lower of cost or market adjustment	(21.5)	(3)
Utility Cost Of Gas | Washington Gas Light Company
Accounting Policies [Table] [Line Items]
Lower of cost or market adjustment	$ (1.3)	$ (0.2)

Accounting Policies - Changes i

Accounting Policies - Changes in Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
WGL
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at beginning of year	$ 207.7	$ 181.2
Liabilities incurred in the period	12.1	8.4
Liabilities settled in the period	(16.9)	(14.6)
Accretion expense	7.4	7.8
Revisions in estimated cash flows	0	24.9
Asset retirement obligations at the end of the year	210.3	207.7
Washington Gas Light Company
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at beginning of year	205.9	179.8
Liabilities incurred in the period	10.4	8.1
Liabilities settled in the period	(16.9)	(14.6)
Accretion expense	7.2	7.7
Revisions in estimated cash flows	0	24.9
Asset retirement obligations at the end of the year	206.6	205.9
Asset retirement obligation, current	$ 7.2	7
Washington Gas Light Company | Springfield Operations Center
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Liabilities settled in the period		$ 1.6

Regulated Operations (Details)

Regulated Operations (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Sep. 30, 2015
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Current		$ 15,294	$ 5,797
Regulatory Assets, Noncurrent		98,592	80,018
Gas costs due from/to customers
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Current		4,100	1,700
Regulatory Liabilities, Current	[1]	12,100	22,600
Interruptible Sharing
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Current	[1]	900	3,300
Regulatory Liabilities, Current	[1]	600	2,600
Revenue normalization mechanisms for Maryland and Virginia
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Current	[1]	6,600	0
Regulatory Liabilities, Current	[1]	0	8,400
Plant Recovery Mechanisms
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Current		3,700	800
Regulatory Liabilities, Current		300	1,000
Total current
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Current		15,300	5,800
Regulatory Liabilities, Current		13,000	34,600
Accrued Asset Removal Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Liability, Noncurrent		310,800	325,500
Deferred Gas Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1],[2]	179,900	190,700
Pension and other post-retirement benefit costs-trackers
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0	100
Deferred pension costs/income-trackers
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		29,800	38,000
Pensions
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1],[3]	193,400	173,900
Other Post Retirement Benefits
Public Utilities, General Disclosures [Line Items]
Regulatory Liability, Noncurrent	[1],[3]	113,900	104,400
Total pension and other post-retirement benefits
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		223,200	212,000
Regulatory Liability, Noncurrent		113,900	104,400
Income tax-related amounts due from/to customers
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[4]	33,600	31,700
Regulatory Liability, Noncurrent	[4]	3,600	4,200
Losses/gains on issuance and extinguishments of debt and interest-rate derivative instruments
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1],[5]	17,500	11,100
Regulatory Liability, Noncurrent	[1],[5]	1,500	1,600
Deferred gain on sale of assets
Public Utilities, General Disclosures [Line Items]
Regulatory Liability, Noncurrent	[1]	1,000	1,400
Rights-of-way fees
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1]	300	1,600
Business process outsourcing and related costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1]	9,800	2,700
Non-retirement post-employment benefits
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1],[6]	19,200	18,900
Deferred integrity management expenditures
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1],[7]	8,500	5,100
Recoverable portion of abandoned LNG facility
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		4,300	5,000
Environmental response costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1],[8]	1,300	1,800
Other regulatory expenses
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1]	4,100	2,100
Regulatory Liability, Noncurrent	[1]	8,300	9,900
Total other
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		98,600	80,000
Regulatory Liability, Noncurrent		14,400	17,100
Total deferred
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		501,700	482,700
Regulatory Liability, Noncurrent		439,100	447,000
Total
Public Utilities, General Disclosures [Line Items]
Regulatory Assets		517,000	488,500
Regulatory Liabilities		$ 452,100	$ 481,600
[1]	Washington Gas does not earn its overall rate of return on these assets. Washington Gas is allowed to recover and required to pay, using short-term interest rates, the carrying costs related to billed gas costs due from and to its customers in the District of Columbia and Virginia jurisdictions.
[2]	Includes fair value of derivatives, which are not included in customer bills until settled.
[3]	Refer to Note 10-Pension and Other Post-Retirement Benefit Plans for a further discussion of these amounts.
[4]	This balance represents amounts due from customers for deferred tax liabilities related to tax benefits on deduction flowed directly to customers prior to the adoption of income tax normalization for ratemaking purposes.
[5]	The losses or gains on the issuance and extinguishment of debt and interest-rate derivative instruments include unamortized balances from transactions executed in prior fiscal years. These transactions create gains and losses that are amortized over the remaining life of the debt as prescribed by regulatory accounting requirements.
[6]	Represents the timing difference between the recognition of workers compensation and short-term disability costs in accordance with generally accepted accounting principles and the way these costs are recovered through rates.
[7]	This balance represents amounts for deferred expenditures associated with Washington Gas’ Distribution Integrity Management Program (DIMP) in Virginia.
[8]	This balance represents allowed remediation expenditures at Washington Gas sites to be recovered through rates for Maryland and the District of Columbia. The recovery period is over several years.

Accounts Payable and Other Ac56

Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Accounts Payable and Accrued Liabilities [Line Items]
Accounts payable—trade	$ 353	$ 277.3
Employee benefits and payroll accruals	34.4	31.4
Other accrued liabilities	18	16.4
Total	405.4	325.1
Washington Gas Light Company
Accounts Payable and Accrued Liabilities [Line Items]
Accounts payable—trade	161	122.2
Employee benefits and payroll accruals	32.2	29.5
Other accrued liabilities	11.8	7.6
Total	$ 205	$ 159.3

Short-Term Debt (Details)

Short-Term Debt (Details) $ in Thousands		Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)
Short Term Debt [Line Items]
Less: Commercial Paper		$ (331,385)	$ (332,000)
Committed credit
Short Term Debt [Line Items]
Unsecured revolving credit facility	[1]	800,000	800,000
Less: Commercial Paper		(269,000)	(332,000)
Net committed credit available		$ 531,000	$ 468,000
Short-term debt weighted average interest rate		0.69%	0.26%
Outstanding bank loans		$ 0	$ 0
Maximum
Short Term Debt [Line Items]
Ratio of Indebtedness to Net Capital		1
Ratio Of Indebtedness To Net Capital Percentage		65.00%
Minimum
Short Term Debt [Line Items]
Ratio of Indebtedness to Net Capital		0.65
WGL
Short Term Debt [Line Items]
Revolving credit facility additional borrowings		$ 100,000
Revolving credit facility maximum borrowing capacity		$ 550,000
Ratio Of Indebtedness To Net Capital Percentage		56.00%
WGL | Committed credit
Short Term Debt [Line Items]
Unsecured revolving credit facility	[1],[2]	$ 450,000	450,000
Less: Commercial Paper	[2]	(227,000)	(243,000)
Net committed credit available	[2]	$ 223,000	$ 207,000
Short-term debt weighted average interest rate	[2]	0.73%	0.30%
Washington Gas Light Company
Short Term Debt [Line Items]
Less: Commercial Paper		$ (104,385)	$ (89,000)
Revolving credit facility additional borrowings		100,000
Revolving credit facility maximum borrowing capacity		$ 450,000
Ratio Of Indebtedness To Net Capital Percentage		48.00%
Project financing receivable		$ 73,300
Project financing payable		62,400
Reserve for bad debt		0
Washington Gas Light Company | Committed credit
Short Term Debt [Line Items]
Unsecured revolving credit facility	[1]	350,000	350,000
Less: Commercial Paper		(42,000)	(89,000)
Net committed credit available		$ 308,000	$ 261,000
Short-term debt weighted average interest rate		0.46%	0.16%
Outstanding bank loans		$ 0	$ 0
[1]	Both WGL and Washington Gas have the right to request extensions with the banks’ approval. WGL’s revolving credit facility permits it to borrow an additional $100 million, with the banks’ approval, for a total of $550 million. Washington Gas’ revolving credit facility permits it to borrow an additional $100 million, with the banks’ approval, for a total of $450 million.
[2]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Long Term Debt (Details)

Long Term Debt (Details) - USD ($)		Feb. 18, 2016	Sep. 30, 2016		Sep. 30, 2015	Sep. 16, 2016
Long Term Debt
Unamortized discount			$ (1,700,000)		$ (1,799,000)
Less-current maturities			0		25,000,000
Long-Term Debt Maturities
Long-term debt			1,444,300,000		944,201,000
Total | Long-term debt outstanding
Long Term Debt
Principal	[1]		1,446,000,000		971,000,000
Unamortized discount			(1,700,000)		(1,800,000)
Less-current maturities					25,000,000
Total Long-Term Debt			$ 1,444,300,000		$ 994,200,000
Weighted Average Interest Rate			4.21%		5.08%
Total Consolidated Issuances
Long Term Debt
Principal	[2]		$ 500,000,000		$ 300,000,000
Maturities
Long-Term Debt Maturities
2,018	[3]		250,000,000
2,019	[3]		50,000,000
2,020	[3]		150,000,000
Thereafter	[3]		996,000,000
Total	[3]		1,446,000,000
Long-term debt	[3]		1,446,000,000
WGL | Long-term debt outstanding
Long Term Debt
Principal	[1],[4]		500,000,000		250,000,000
Unamortized discount	[4]		(1,600,000)		(1,700,000)
Less-current maturities	[4]				0
Total Long-Term Debt	[4]		$ 498,400,000		$ 248,300,000
Weighted Average Interest Rate	[4]		2.50%		3.66%
WGL | Term loan
Long Term Debt
Additional borrowing capacity		$ 100,000,000
Term Loans Maximum Borrowing Capacity		350,000,000
Principal		$ 250,000,000
Term of extension option		1 year
WGL | Issuances
Long Term Debt
Total Long-Term Debt	[2]		$ 250,000,000	[5]	$ 250,000,000
WGL | 2/18/2018 | Issuances
Long Term Debt
Principal	[2],[5]		$ 250,000,000
Interest Rate	[5]		1.34%
Effective Cost	[5],[6]		1.34%
Nominal Maturity Date	[5]		Feb. 18, 2018
WGL | 11/1/2019 | Issuances
Long Term Debt
Principal	[2]				$ 100,000,000
Interest Rate					2.25%
Effective Cost	[6]				2.42%
Nominal Maturity Date					Nov. 1, 2019
WGL | 11/1/2044 | Issuances
Long Term Debt
Principal	[2]				$ 125,000,000
Interest Rate					4.60%
Effective Cost	[6]				5.11%
Nominal Maturity Date					Nov. 1, 2044
WGL | 11/1/2044 | Issuances
Long Term Debt
Principal	[2]				$ 25,000,000
Interest Rate					4.60%
Effective Cost	[6]				5.53%
Nominal Maturity Date					Nov. 1, 2044
WGL | Maturities
Long Term Debt
Unamortized discount			$ 1,600,000
Long-Term Debt Maturities
2,018	[3],[7]		250,000,000
2,020	[3],[7]		100,000,000
Thereafter	[3],[7]		150,000,000
Total	[3],[7]		500,000,000
Long-term debt	[3],[7]		500,000,000
Washington Gas Light Company
Long Term Debt
Unamortized discount			(109,000)		$ (115,000)
Less-current maturities			0		(25,000,000)
Long-Term Debt Maturities
Long-term debt			945,891,000		695,885,000
Washington Gas Light Company | Long-term debt outstanding
Long Term Debt
Principal	[1]		946,000,000		721,000,000
Unamortized discount			(100,000)		(100,000)
Less-current maturities					25,000,000
Total Long-Term Debt			$ 945,900,000		$ 695,900,000
Weighted Average Interest Rate			5.12%		5.58%
Washington Gas Light Company | Medium-term Notes
Long Term Debt
Additional borrowing capacity			$ 350,000,000
Washington Gas Light Company | Medium-term Notes | Unsecured Medium Term Notes Due Year Thirty
Long Term Debt
Principal						$ 250,000,000
Interest Rate						3.796%
Washington Gas Light Company | Issuances
Long Term Debt
Total Long-Term Debt	[2]		250,000,000		$ 50,000,000
Washington Gas Light Company | Total
Long Term Debt
Total Long-Term Debt	[2]		25,000,000		20,000,000
Washington Gas Light Company | 3/15/2046 | Issuances
Long Term Debt
Principal	[2]		$ 250,000,000
Interest Rate			3.80%
Effective Cost	[6]		4.01%
Nominal Maturity Date			Mar. 15, 2046
Washington Gas Light Company | 12/15/2044 | Issuances
Long Term Debt
Principal	[2]				$ 50,000,000
Interest Rate					4.24%
Effective Cost	[6]				4.41%
Nominal Maturity Date					Dec. 15, 2044
Washington Gas Light Company | Maturities
Long Term Debt
Unamortized discount			$ 109,000
Long-Term Debt Maturities
2,019	[3]		50,000,000
2,020	[3]		50,000,000
Thereafter	[3]		846,000,000
Total	[3]		946,000,000
Long-term debt	[3]		946,000,000
Washington Gas Light Company | 1/18/2016 | Retirements
Long Term Debt
Principal	[2]		$ 25,000,000
Interest Rate			5.17%
Nominal Maturity Date			Jan. 18, 2016
Washington Gas Light Company | 8/9/2015 | Retirements
Long Term Debt
Principal	[2]				$ 20,000,000
Interest Rate					4.83%
Nominal Maturity Date					Aug. 9, 2015
Washington Gas Light Company | First Mortgage
Long Term Debt
Mortgage Debt Outstanding			$ 0		$ 0
[1]	Includes Senior Notes and term loans for WGL and both MTNs and private placement notes for Washington Gas. Represents face value including current maturities.
[2]	Represents face amount.
[3]	Excludes unamortized discounts of $1.6 million and $0.1 million at September 30, 2016, for WGL and Washington Gas, respectively.
[4]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.
[5]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.
[6]	The estimated effective cost of the issued notes, including consideration of issuance fees and hedge costs.
[7]	WGL includes WGL Holdings and all subsidiaries other than Washington Gas.

Common Stock (Details)

Common Stock (Details) - USD ($) $ in Millions		Nov. 24, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock outstanding (in shares)			51,080,612	49,728,662
Common stock reserves (in shares)			8,252,975
Omnibus Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserves (in shares)	[1]		2,790,712
Dividend reinvestment and common stock purchase plan member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserves (in shares)			2,775,341
Employee savings plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserves (in shares)			637,196
Directors Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserves (in shares)			68,694
ATM Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserves (in shares)			1,981,032
Total Aggregate Sales Price of Stock to be Issued		$ 150
Issuance of common stock (in shares)			1,162,305
Proceeds from Stock Issued During Period			$ 78.2
[1]	In March 2007, WGL adopted a shareholder-approved Omnibus Incentive Compensation Plan to replace on a prospective basis the 1999 Incentive Compensation Plan. In December 2015, the Board of Directors approved the 2016 Omnibus Incentive Compensation Plan that became effective upon shareholder approval at WGL's Annual Meeting of Stockholders on March 1, 2016. The plan was included as an exhibit to WGL's proxy statement under cover of Form 14A filed on January 20, 2016. Following shareholder approval of the 2016 Omnibus Incentive Compensation Plan, WGL will no longer make equity grants under the 2007 Omnibus Incentive Compensation Plan (but shares issued pursuant to outstanding grants under the 2007 plan will be issued pursuant to that plan). Refer to Note 11—Stock-Based Compensation for a discussion regarding our stock-based compensation plans.

Preferred Stock (Details)

Preferred Stock (Details) - $ / shares	Sep. 30, 2016	Sep. 30, 2015
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0	$ 0
Washington Gas Light Company
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	0	$ 0
Series One | Washington Gas Light Company
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 4.80
Preferred Stock, Shares Outstanding (in shares)	150,000
Preferred Stock, Liquidation Preference Per Share Involuntary (in dollars per share)	$ 100
Preferred Stock Liquidation Preference Voluntary (in dollars per share)	101
Preferred Stock, Redemption Price Per Share (in dollars per share)	101
Series Two | Washington Gas Light Company
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 4.25
Preferred Stock, Shares Outstanding (in shares)	70,600
Preferred Stock, Liquidation Preference Per Share Involuntary (in dollars per share)	$ 100
Preferred Stock Liquidation Preference Voluntary (in dollars per share)	105
Preferred Stock, Redemption Price Per Share (in dollars per share)	105
Series Three | Washington Gas Light Company
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 5
Preferred Stock, Shares Outstanding (in shares)	60,000
Preferred Stock, Liquidation Preference Per Share Involuntary (in dollars per share)	$ 100
Preferred Stock Liquidation Preference Voluntary (in dollars per share)	102
Preferred Stock, Redemption Price Per Share (in dollars per share)	$ 102

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Stock options outstanding (in shares)	0
Antidilutive Securities (in shares)	86,500	0	0
NET INCOME APPLICABLE TO COMMON STOCK	$ 167,594	$ 131,259	$ 105,940
Basic (in shares)	50,369,000	49,794,000	51,759,000
Basic earnings per average common share	$ 3.33	$ 2.64	$ 2.05
Stock-based compensation plan	195,000	266,000	11,000
Total average common shares outstanding diluted (in shares)	50,564,000	50,060,000	51,770,000
Diluted earnings per average common share (in dollars per share)	$ 3.31	$ 2.62	$ 2.05

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
WGL
Income Taxes [Line Items]
Current deferred tax asset reclassed to non-current deferred tax liability		$ 32,800
Interest associated with uncertain tax positions	$ 0	0	$ 0
Washington Gas Light Company
Income Taxes [Line Items]
Tax increase realized from tax sharing agreement	1,100
Tax savings realized from tax sharing agreement	0	500	2,900
Current deferred tax asset reclassed to non-current deferred tax liability		24,700
Unrecognized tax benefits increase (decrease)	3,700
Interest associated with uncertain tax positions	$ 0	$ 0	$ 0

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Deferred
Total income tax expense	$ 98,074	$ 83,804	$ 57,254
WGL
Current
Federal	(57,690)	(18,639)	29,976
State	(1,983)	2,977	5,149
Total current	(59,673)	(15,662)	35,125
Deferred
Total deferred	163,879	104,405	25,795
Amortization of investment tax credits	(6,132)	(4,939)	(3,666)
Total income tax expense	98,074	83,804	57,254
WGL | Accelerated Depreciation [Member]
Deferred
Federal	93,175	71,529	35,747
State	12,993	13,739	9,822
WGL | Other Federal [Member]
Deferred
Federal	49,638	17,726	(18,014)
State	8,073	1,411	(1,760)
Washington Gas Light Company
Current
Federal	(48,064)	(5,305)	37,098
State	(2,957)	907	4,262
Total current	(51,021)	(4,398)	41,360
Deferred
Total deferred	123,482	76,621	7,050
Amortization of investment tax credits	(795)	(832)	(876)
Total income tax expense	71,666	71,391	47,534
Washington Gas Light Company | Accelerated Depreciation [Member]
Deferred
Federal	93,385	71,046	34,833
State	13,081	13,701	9,540
Washington Gas Light Company | Other Federal [Member]
Deferred
Federal	13,826	(6,619)	(30,523)
State	$ 3,190	$ (1,507)	$ (6,800)

Income Taxes (Tax Rate Reconcil

Income Taxes (Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Taxes [Line Items]
Total income tax expense	$ 98,074	$ 83,804	$ 57,254
WGL
Income Taxes [Line Items]
Income taxes at statutory federal tax rate	93,253	75,760	57,580
Accelerated depreciation less amount deferred	908	1,187	1,875
Amortization of investment tax credits	(6,132)	(4,939)	(3,666)
Cost of removal	(3,722)	(2,721)	(4,902)
State income taxes-net of federal benefit	12,969	11,109	8,734
Medicare Part D adjustment	0	0	(3,621)
ASDHI impairment	0	1,969	0
Other items-net	798	1,439	1,254
Total income tax expense	$ 98,074	$ 83,804	$ 57,254
Statutory federal income tax rate (%)	35.00%	35.00%	35.00%
Accelerated depreciation less amount deferred (%)	0.34%	0.55%	1.14%
Amortization of investment tax credits (%)	(2.30%)	(2.28%)	(2.23%)
Cost of removal (%)	(1.40%)	(1.26%)	(2.98%)
State income taxes-net of federal benefit (%)	4.87%	5.13%	5.31%
Medicare Part D adjustment (%)	0.00%	0.00%	(2.20%)
ASDHI impairment (%)	0.00%	0.91%	0.00%
Other items-net (%)	0.30%	0.66%	0.76%
Effective Income Tax Rate, Continuing Operations, Total	36.81%	38.71%	34.80%
Washington Gas Light Company
Income Taxes [Line Items]
Income taxes at statutory federal tax rate	$ 64,673	$ 63,024	$ 51,050
Accelerated depreciation less amount deferred	1,936	2,108	1,875
Amortization of investment tax credits	(795)	(832)	(876)
Cost of removal	(3,722)	(2,721)	(4,902)
State income taxes-net of federal benefit	8,310	8,986	6,711
Consolidated tax sharing allocation	1,073	(533)	(2,862)
Medicare Part D adjustment	0	0	(3,621)
Other items-net	191	1,359	159
Total income tax expense	$ 71,666	$ 71,391	$ 47,534
Statutory federal income tax rate (%)	35.00%	35.00%	35.00%
Accelerated depreciation less amount deferred (%)	1.05%	1.17%	1.29%
Amortization of investment tax credits (%)	(0.43%)	(0.46%)	(0.60%)
Cost of removal (%)	(2.01%)	(1.51%)	(3.36%)
State income taxes-net of federal benefit (%)	4.50%	4.99%	4.60%
Consolidated tax sharing allocation (%)	0.58%	(0.30%)	(1.96%)
Medicare Part D adjustment (%)	0.00%	0.00%	(2.48%)
Other items-net (%)	0.10%	0.76%	0.09%
Effective Income Tax Rate, Continuing Operations, Total	38.79%	39.65%	32.58%

Income Taxes (Components of Def

Income Taxes (Components of Deferred Tax Assets (Liabilities)) (Details) - Non-current - USD ($) $ in Thousands		Sep. 30, 2016	Sep. 30, 2015
Deferred Income Tax Assets:
Pensions		$ 60,685	$ 44,468
Uncollectible accounts		12,441	10,389
Inventory overheads		5,046	5,873
Employee compensation and benefits		49,443	57,230
Derivatives		58,203	43,891
Deferred gas costs		0	2,406
Solar grant/ investment tax credit		64,149	53,067
Tax credit carry forward		118,980	55,040
Net operating loss		27,741	0
Other	[1]	1,075	5,640
Total assets		397,763	278,004
Deferred Income Tax Liabilities:
Other post-retirement benefits		69,899	54,860
Accelerated depreciation and other plant related items		949,807	794,099
Losses/gains on reacquired debt		1,155	1,292
Income taxes recoverable through future rates		71,352	68,245
Deferred gas costs		1,696	815
Partnership basis difference		27,532	29,468
Valuation allowances		2,188	2,188
Total liabilities		1,123,629	950,967
Total Liabilities		725,866	672,963
Deferred income tax assets		897
Washington Gas Light Company
Deferred Income Tax Assets:
Pensions		59,878	43,748
Uncollectible accounts		8,054	7,637
Inventory overheads		5,046	5,873
Employee compensation and benefits		43,755	38,857
Derivatives		27,394	38,887
Deferred gas costs		0	2,406
Net operating loss		24,588	0
Other		0	862
Total assets		168,715	138,270
Deferred Income Tax Liabilities:
Other post-retirement benefits		69,520	54,566
Accelerated depreciation and other plant related items		783,919	681,108
Losses/gains on reacquired debt		1,155	1,292
Income taxes recoverable through future rates		71,063	67,953
Deferred gas costs		1,696	815
Other		5,082	1,300
Total liabilities		932,435	807,034
Deferred Tax Liabilities, Net		$ (763,720)	$ (668,764)
[1]	Includes $0.897 million in deferred income tax assets reported in "Deferred charges and other assets" on the consolidated balance sheet

Income Taxes (Unrecognized Tax

Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Unrecognized Tax Benefits
Total unrecognized tax benefits, beginning balance	$ 38,627	$ 32,613	$ 25,051
Increases in tax positions relating to current year	10,645	12,848	10,512
Decreases in tax positions relating to prior year	(6,989)	(6,834)	(2,950)
Total unrecognized tax benefits, ending balance	$ 42,283	$ 38,627	$ 32,613

Pension and Other Post-retire67

Pension and Other Post-retirement Benefit Plans (Narrative) (Details) - USD ($)	Jan. 01, 2018	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Total matching contributions			$ 5,100,000		$ 4,600,000		$ 4,200,000
Total supplemental contributions			2,600,000		2,100,000		1,600,000
Prior service credit related to plan amendment		$ 26,100,000	$ 891,000	[1]	(696,000)	[1]	(6,095,000)
Percentage of prior years asset gains and losses recognized			20.00%
Realized and unrealized gains and losses on equities prior year			80.00%
Realized and unrealized gains and losses on equities second prior year			60.00%
Realized and unrealized gains and losses on equities third prior year			40.00%
Realized and unrealized gains and losses on equities fourth prior year			20.00%
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
HRA Stipend Increase			0.00%
Defined Benefit Plan Target Allocation Percentage [Abstract]
Asset Class Allocations Allowed Range Within Plus Or Minus			5.00%
EGWP effect on post retirement benefits					800,000
Fiscal year 2015
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rates For Non Medicare Eligible Retirees			6.70%
Scenario, Forecast
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rates For Non Medicare Eligible Retirees										6.30%
Future Healthcare Cost Trend Rates									3.20%
HRA Stipend Increase									3.00%	0.00%
Scenario, Forecast | Fiscal year 2016
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Health Care Cost Trend Rates For Non Medicare Eligible Retirees										6.30%
Future Healthcare Cost Trend Rates								2.20%	3.20%
Scenario, Forecast | Fiscal year 2015
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Future Healthcare Cost Trend Rates								2.20%
Union Eligible Employee
Defined Benefit Plan Target Allocation Percentage [Abstract]
US Large Cap Equities			50.00%
Fixed Income And Cash			50.00%
Management Employee
Defined Benefit Plan Target Allocation Percentage [Abstract]
US Large Cap Equities			60.00%
Fixed Income And Cash			40.00%
Aggregate Cost Limit Per Individual | Scenario, Forecast
Defined Benefit Plan Disclosure [Line Items]
Retiree Medical employer sponsored coverage limits under amendment	$ 11,850
Aggregate Cost Limit Per Family | Scenario, Forecast
Defined Benefit Plan Disclosure [Line Items]
Retiree Medical employer sponsored coverage limits under amendment	$ 30,950
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Prior service credit related to plan amendment			$ 300,000		300,000		300,000
The projected benefit obligation (PBO)		892,200,000	1,005,000,000		892,200,000
Increase in PBO due to changes in mortality assumptions			$ 0		46,800,000
Defined Benefit Plan Target Allocation Percentage [Abstract]
US Large Cap Equities			32.50%
US Small Mid Cap Equities			4.50%
International Equities			8.00%
Real Estate Investments			5.00%
Fixed Income And Cash			50.00%
Employer payment current fiscal year			$ 0
Estimated future employer contributions in next fiscal year			0
Other post-retirement benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service credit related to plan amendment			(17,700,000)		(15,300,000)		$ (9,600,000)
Increase in PBO due to changes in mortality assumptions			0		15,300,000
Defined Benefit Plan Target Allocation Percentage [Abstract]
Employer payment current fiscal year			14,900,000
Estimated future employer contributions in next fiscal year			8,300,000
DB Restoration
Defined Benefit Plan Disclosure [Line Items]
The projected benefit obligation (PBO)		2,300,000	3,900,000		2,300,000
DB SERP
Defined Benefit Plan Disclosure [Line Items]
The projected benefit obligation (PBO)		$ 53,000,000	60,400,000		$ 53,000,000
Defined Benefit Plan Target Allocation Percentage [Abstract]
Employer payment current fiscal year			1,800,000
Estimated future employer contributions in next fiscal year			$ 6,300,000
Defined benefit plan percentage of expenses recovered through rates			50.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage Of supplemental contribution			6.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Percentage Of supplemental contribution			4.00%
[1]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 10—Pension and other post-retirement benefit plans for additional details.

Pension and Other Post-retire68

Pension and Other Post-retirement Benefit Plans (Post-Retirement Benefits Table) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
Change in plan assets
Fair Value of plan assets at beginning of year		$ 27,700		$ 23,800
Fair value of plan assets at end of year		22,400		27,700		$ 23,800
Total Recognized
Non-current asset		180,686		138,629
Non-current liability		(228,377)		(176,128)
Pension Plan
Change in projected benefit obligation
Benefit obligation at beginning of year	[1]	947,500		917,100
Service cost		14,200	[1]	15,500	[1]	14,000
Interest cost		41,300	[1]	39,100	[1]	40,400
Change in plan benefits	[1]	500		600
Actuarial loss (gain)	[1]	110,500		19,200
Benefits Paid	[1]	(44,700)		(44,000)
Projected benefit obligation at end of year	[1]	1,069,300		947,500		917,100
Change in plan assets
Fair Value of plan assets at beginning of year	[1]	780,200		804,700
Actual return on plan assets	[1]	115,000		19,900
Company contributions	[1]	1,800		1,800
Expenses	[1]	(2,300)		(2,200)
Benefits Paid	[1]	(44,700)		(44,000)
Fair value of plan assets at end of year	[1]	850,000		780,200		804,700
Funded status at end of year	[1]	(219,300)		(167,300)
Total Recognized
Current liability	[1]	(6,300)		(4,800)
Non-current liability	[1]	(213,000)		(162,500)
Total Recognized	[1]	(219,300)		(167,300)
Other post-retirement benefits
Change in projected benefit obligation
Benefit obligation at beginning of year		299,900	[2]	343,200
Service cost		4,600		7,100		7,600
Interest cost		13,100		14,700		18,700
Change in plan benefits				(26,100)
Actuarial loss (gain)		19,500		(23,700)
Retiree Contributions		2,300		2,000
Employer group waiver plan rebates		1,200		2,400
Benefits Paid		(16,300)		(19,700)
Projected benefit obligation at end of year		324,300	[2]	299,900	[2]	343,200
Change in plan assets
Fair Value of plan assets at beginning of year		438,500		439,600
Actual return on plan assets		65,100		(300)
Company contributions		14,900		16,000
Retiree Contributions and employer group waiver plan rebates		3,500		3,600
Expenses		(700)		(700)
Benefits Paid		(16,300)		(19,700)
Fair value of plan assets at end of year		505,000		438,500		$ 439,600
Funded status at end of year		180,700		138,600
Total Recognized
Non-current asset		180,700		138,600
Total Recognized		$ 180,700		$ 138,600
[1]	The DB SERP and DB Restoration, included in pension benefits in the table above, have no assets.
[2]	For the Health and Life Benefits, the change in projected benefit obligation represents the accumulated benefit obligation.

Pension and Other Post-retire69

Pension and Other Post-retirement Benefit Plans (Projected and ABO) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 1,005	$ 892.2
Accumulated benefit obligation	922.3	822.8
DB SERP
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	60.4	53
Accumulated benefit obligation	56.5	48.7
DB Restoration
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	3.9	2.3
Accumulated benefit obligation	$ 2.3	$ 1.2

Pension and Other Post-retire70

Pension and Other Post-retirement Benefit Plans (Unrecognized Costs Income Recorded on BS) (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Unrecognized Costs/Income Recorded on the Balance Sheet
AOCI, tax expense (benefit)		$ 5.8	$ 5.1
Pension Plan
Unrecognized Costs/Income Recorded on the Balance Sheet
Unrecognized actuarial net loss		211.9	190.1
Unrecognized prior service cost (credit)		1.5	1.5
Total		213.4	191.6
Regulatory asset	[1]	193.4	173.9
Pre-tax accumulated other comprehensive loss (gain)	[2]	20	17.7
Total		213.4	191.6
Deferred Income Tax Benefit		4.1	6.1
Other post-retirement benefits
Unrecognized Costs/Income Recorded on the Balance Sheet
Unrecognized actuarial net loss		18.1	43.8
Unrecognized prior service cost (credit)		(142.5)	(160.2)
Total		(124.4)	(116.4)
Regulatory asset	[1]	(118)	(110.5)
Pre-tax accumulated other comprehensive loss (gain)	[2]	(6.4)	(5.9)
Total		$ (124.4)	$ (116.4)
[1]	The regulatory liability recorded on our balance sheets at September 30, 2016 and 2015 is net of a deferred income tax benefit of $4.1 million and $6.1 million, respectively.
[2]	The total amount of accumulated other comprehensive loss recorded on our balance sheets at September 30, 2016 and 2015 is net of an income tax benefit of $5.8 million and $5.1 million, respectively.

Pension and Other Post-retire71

Pension and Other Post-retirement Benefit Plans (Recognized in Curent and Next FY) (Details) $ in Millions	12 Months Ended
	Sep. 30, 2016USD ($)
Pension Plan | Regulatory Assets and Liabilities
Amounts Recognized During Current Fiscal Year
Actuarial net loss	$ 15.3
Prior service cost (credit)	0.2
Total	15.5
Amounts to be Recognized During Next Fiscal Year
Actuarial net loss	19.9
Prior service cost (credit)	0.2
Total	20.1
Pension Plan | Accumulated Other Comprehensive Loss
Amounts Recognized During Current Fiscal Year
Actuarial net loss	1.5
Prior service cost (credit)	0.1
Total	1.6
Amounts to be Recognized During Next Fiscal Year
Actuarial net loss	2.1
Prior service cost (credit)	0.1
Total	2.2
Health and Life Benefits | Regulatory Assets and Liabilities
Amounts Recognized During Current Fiscal Year
Actuarial net loss	1.2
Prior service cost (credit)	(16.8)
Total	(15.6)
Amounts to be Recognized During Next Fiscal Year
Actuarial net loss	0.7
Prior service cost (credit)	(16.7)
Total	(16)
Health and Life Benefits | Accumulated Other Comprehensive Loss
Amounts Recognized During Current Fiscal Year
Actuarial net loss	0.1
Prior service cost (credit)	(0.9)
Total	(0.8)
Amounts to be Recognized During Next Fiscal Year
Prior service cost (credit)	(0.9)
Total	$ (0.9)

Pension and Other Post-retire72

Pension and Other Post-retirement Benefit Plans (Components of Net Periodic Benefit Cost Income) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Recognized prior service cost (credit)	$ 26,100	$ 891	[1]	$ (696)	[1]	$ (6,095)
Recognized actuarial loss		936	[1]	1,195	[1]	(1,594)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		14,200	[2]	15,500	[2]	14,000
Interest cost		41,300	[2]	39,100	[2]	40,400
Expected return on plan assets		(40,900)		(44,600)		(41,000)
Recognized prior service cost (credit)		300		300		300
Recognized actuarial loss		16,900		18,700		16,800
Net periodic benefit cost		31,800		29,000		30,500
Amount allocated to construction projects		(5,600)		(4,600)		(4,300)
Amount deferred as regulatory asset (liability)-net		7,100		7,100		7,000
Amount charged (credited) to expense		33,300		31,500		33,200
Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost		4,600		7,100		7,600
Interest cost		13,100		14,700		18,700
Expected return on plan assets		(20,400)		(20,800)		(19,300)
Recognized prior service cost (credit)		(17,700)		(15,300)		(9,600)
Recognized actuarial loss		1,200		4,400		5,000
Net periodic benefit cost		(19,200)		(9,900)		2,400
Amount allocated to construction projects		4,100		1,900		(400)
Amount deferred as regulatory asset (liability)-net		(200)		(200)		(2,300)
Amount charged (credited) to expense		$ (15,300)		$ (8,200)		$ (300)
[1]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note 10—Pension and other post-retirement benefit plans for additional details.
[2]	The DB SERP and DB Restoration, included in pension benefits in the table above, have no assets.

Pension and Other Post-retire73

Pension and Other Post-retirement Benefit Plans (Benefit Obligations and Net Periodic Benefit Cost Assumptions) (Details)		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Pension Plan
Net Periodic Benefit Cost Assumptions [Abstract]
Expected long-term return on plan assets	[1]	6.00%	6.75%	6.50%
Pension Plan | Maximum
Benefit Obligations Assumptions [Abstract]
Discount rate	[2]	3.70%	4.50%
Rate of compensation increase		4.10%	4.10%
Net Periodic Benefit Cost Assumptions [Abstract]
Discount rate	[3]	4.50%	4.40%	5.00%
Rate of compensation increase	[4]	4.10%	4.10%	5.15%
Pension Plan | Minimum
Benefit Obligations Assumptions [Abstract]
Discount rate	[2]	3.40%	4.10%
Rate of compensation increase		3.50%	3.50%
Net Periodic Benefit Cost Assumptions [Abstract]
Discount rate	[3]	4.10%	4.00%	4.50%
Rate of compensation increase	[4]	3.50%	3.50%	3.85%
Health and Life Benefits
Benefit Obligations Assumptions [Abstract]
Discount rate	[2]	3.70%	4.50%
Rate of compensation increase		4.10%	4.10%
Net Periodic Benefit Cost Assumptions [Abstract]
Discount rate	[3]	4.50%	4.40%
Expected long-term return on plan assets	[1]	5.75%	6.25%	6.25%
Rate of compensation increase	[4]	4.10%	4.10%	3.85%
Assumed Income Tax Rate		45.30%
Health and Life Benefits | Maximum
Net Periodic Benefit Cost Assumptions [Abstract]
Discount rate	[3]			5.10%
Health and Life Benefits | Minimum
Net Periodic Benefit Cost Assumptions [Abstract]
Discount rate	[3]			4.60%
[1]	For health and life benefits, the expected returns for certain funds may be lower due to certain portions of income that are subject to an assumed income tax rate of 45.3%.
[2]	The decrease in the discount rate in fiscal year 2016 compared to prior years primarily reflects the decrease in long-term interest rates.
[3]	The changes in the discount rates over the last three fiscal years primarily reflect the changes in long-term interest rates.
[4]	The changes in the rate of compensation reflects the best estimates of actual future compensation levels including consideration of general price levels, productivity, seniority, promotion, and other factors such as inflation rates.

Pension and Other Post-retire74

Pension and Other Post-retirement Benefit Plans (Healthcare Trends) (Details) $ in Millions	12 Months Ended
	Sep. 30, 2016USD ($)
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Increase one percentage point total service and interest cost components	$ 0.6
Decrease one percentage point total service and interest cost components	(0.5)
Increase one percentage point post-retirement benefit obligation	5.9
Decrease one percentage point post-retirement benefit obligation	$ (5.3)

Pension and Other Post-retire75

Pension and Other Post-retirement Benefit Plans (Plan Assets) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan assets at end of year		$ 22.4	$ 27.7	$ 23.8
Pension Plan
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		851.3	781.9
Receivable (Payable)	[1]	(1.3)	(1.7)
Fair value of plan assets at end of year	[2]	$ 850	$ 780.2	804.7
Percentage of fair value of plan investments		100.20%	100.20%
Percent Receivable (Payable)	[1]	(0.20%)	(0.20%)
Total plan assets percent		100.00%	100.00%
Pension Plan | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 70.8	$ 29.5
Pension Plan | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		758.1	724.7
Pension Plan | Level 3 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		22.4	27.7
Pension Plan | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 0.3	$ 0.8
Percentage of fair value of plan investments		0.00%	0.10%
Pension Plan | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 0.3	$ 0.8
Pension Plan | Equity Securities US Small Cap [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 36.5	$ 28.7
Percentage of fair value of plan investments		4.30%	3.70%
Pension Plan | Equity Securities US Small Cap [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 36.5	$ 28.7
Pension Plan | Equity Securities Preferred [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 1.1	$ 0.1
Percentage of fair value of plan investments		0.10%	0.00%
Pension Plan | Equity Securities Preferred [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 1.1	$ 0.1
Pension Plan | US Treasury Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 135.4	$ 101.3
Percentage of fair value of plan investments		15.90%	13.00%
Pension Plan | US Treasury Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 135.4	$ 101.3
Pension Plan | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 200.6	$ 204.6
Percentage of fair value of plan investments		23.60%	26.20%
Pension Plan | Domestic Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 200.6	$ 204.6
Pension Plan | U S Government Agencies And Sponsored Entities Debt Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 18.2	$ 23.9
Percentage of fair value of plan investments		2.10%	3.10%
Pension Plan | U S Government Agencies And Sponsored Entities Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 18.2	$ 23.9
Pension Plan | Asset-backed Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 1.5	$ 1.7
Percentage of fair value of plan investments		0.30%	0.20%
Pension Plan | Asset-backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 1.5	$ 1.7
Pension Plan | Municipalities
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 13.7	$ 14
Percentage of fair value of plan investments		1.60%	1.80%
Pension Plan | Municipalities | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 13.7	$ 14
Pension Plan | Foreign Corporate Debt Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 45.5	$ 37.1
Percentage of fair value of plan investments		5.40%	4.80%
Pension Plan | Foreign Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 45.5	$ 37.1
Pension Plan | Repurchase Agreements [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[3]		$ 5.3
Percentage of fair value of plan investments	[3]		0.70%
Pension Plan | Repurchase Agreements [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[3]		$ 5.3
Pension Plan | Fixed Income Securities Other [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[4]	$ 6.8	$ 4.7
Percentage of fair value of plan investments	[4]	0.80%	0.60%
Pension Plan | Fixed Income Securities Other [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[4]	$ 6.8	$ 4.7
Pension Plan | Mutual Funds [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[5]	$ 34	$ 29.3
Percentage of fair value of plan investments	[5]	4.00%	3.70%
Pension Plan | Mutual Funds [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[5]	$ 34
Pension Plan | Mutual Funds [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[5]		$ 29.3
Pension Plan | Commingled Funds And Pooled Separate Accounts [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[6]	$ 324.7	$ 302.5
Percentage of fair value of plan investments	[6]	38.20%	38.70%
Pension Plan | Commingled Funds And Pooled Separate Accounts [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[6]	$ 302.3	$ 274.8
Pension Plan | Commingled Funds And Pooled Separate Accounts [Member] | Level 3 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[6]	22.4	27.7
Pension Plan | Private Equity / Limited Partnership
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[7]	$ 31.8	$ 28
Percentage of fair value of plan investments	[7]	3.70%	3.60%
Pension Plan | Private Equity / Limited Partnership | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[7]	$ 31.8	$ 28
Pension Plan | Derivatives [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[8]	$ 1.2	$ (0.1)
Percentage of fair value of plan investments	[8]	0.20%	0.00%
Pension Plan | Derivatives [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[8]	$ 1.2	$ (0.1)
Health and Life Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		504.3	437.8
Receivable (Payable)	[9]	0.7	0.7
Fair value of plan assets at end of year		$ 505	$ 438.5	$ 439.6
Percentage of fair value of plan investments		99.90%	99.80%
Percent Receivable (Payable)	[9]	0.10%	0.20%
Total plan assets percent		100.00%	100.00%
Health and Life Benefits | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 2.2	$ 1.9
Health and Life Benefits | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		502.1	435.9
Health and Life Benefits | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 2.2
Percentage of fair value of plan investments		0.40%
Health and Life Benefits | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 2.2
Health and Life Benefits | US Treasury Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 33.3	$ 27.7
Percentage of fair value of plan investments		6.60%	6.30%
Health and Life Benefits | US Treasury Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 33.3	$ 27.7
Health and Life Benefits | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 38.2	$ 33.5
Percentage of fair value of plan investments		7.60%	7.70%
Health and Life Benefits | Domestic Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 38.2	$ 33.5
Health and Life Benefits | US Government Agencies Debt Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 1.7	$ 1.8
Percentage of fair value of plan investments		0.30%	0.40%
Health and Life Benefits | US Government Agencies Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 1.7	$ 1.8
Health and Life Benefits | Municipalities
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 4.1	$ 4
Percentage of fair value of plan investments		0.80%	0.90%
Health and Life Benefits | Municipalities | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 4.1	$ 4
Health and Life Benefits | Foreign Corporate Debt Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 6.4	$ 4.9
Percentage of fair value of plan investments		1.30%	1.10%
Health and Life Benefits | Foreign Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments		$ 6.4	$ 4.9
Health and Life Benefits | Fixed Income Securities Other [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[10]	$ 2.8	$ 4.3
Percentage of fair value of plan investments	[10]	0.60%	1.00%
Health and Life Benefits | Fixed Income Securities Other [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[10]	$ 2.8	$ 4.3
Health and Life Benefits | Mutual Funds [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[11]		$ 1.9
Percentage of fair value of plan investments	[11]		0.40%
Health and Life Benefits | Mutual Funds [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[11]		$ 1.9
Health and Life Benefits | Commingled Funds [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[11]	$ 415.6	$ 359.7
Percentage of fair value of plan investments	[11]	82.30%	82.00%
Health and Life Benefits | Commingled Funds [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of plan investments	[11]	$ 415.6	$ 359.7
[1]	This category includes Treasury Bills with a pre-commitment from the counterparty to repurchase the same securities on the next business day at an agreed-upon price.
[2]	The DB SERP and DB Restoration, included in pension benefits in the table above, have no assets.
[3]	This category primarily includes non-U.S. government bonds as of September 30, 2016 and Yankee bonds and non-U.S. government bonds as of September 30, 2015.
[4]	At September 30, 2016 and September 30, 2015 the investment in a mutual fund consisted primarily of common stock of non-U.S. based companies.
[5]	At September 30, 2016, investments in commingled funds and a pooled separate account consisted primarily of 85% common stock of large-cap U.S companies; 14% income producing properties located in the United States; and 1% short-term money market investments. As of September 30, 2015, investments in commingled funds and a pooled separate accounts consisted primarily of 80% common stock of large-cap U.S companies; 18% income producing properties located in the United States; and 2% short-term money market investments.
[6]	At September 30, 2016 and 2015, an investments in a private equity/limited partnership consisted of common stock of international companies.
[7]	At September 30, 2016 and 2015, this category included a combination of long-term U.S. Treasury interest rate future contracts, currency forwards, a currency option interest rate swaps, and put and call options on both interest rate swaps and credit default swap index products.
[8]	At September 30, 2016 and September 30, 2015 this net payable primarily represents pending trades for investments purchased net of pending trades for investments sold and interest receivable.
[9]	At September 30, 2016 and September 30, 2015 this net receivable primarily represents pending trades for investments sole and interest receivable net of pending trades for investments purchased.
[10]	At September 30, 2016, investments held by commingled funds in which the plan invests consisted primarily of 68% of common stock of large-cap U.S. companies, 12% of U.S. Government fixed income securities and 20% of corporate bonds. At September 30, 2015, investments held by commingled funds in which the plan invests consisted primarily of 68% of common stock of large-cap U.S. companies,16% of U.S. Government fixed income securities and 16% of corporate bonds.
[11]	At September 30, 2015, investment in mutual funds consisted of a short-term money market fund valued at $1.00 per share.

Pension and Other Post-retire76

Pension and Other Post-retirement Benefit Plans (Pension Plan Assets-Footnotes) (Details) - $ / shares	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Large Cap U.S. Companies Common Stock [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Allocation of investments in comingled funds and pooled separate accounts	85.00%	80.00%
Large Cap U.S. Companies Common Stock [Member] | Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Allocation of investments in comingled funds	68.00%	68.00%
Income Producing Properties [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Allocation of investments in comingled funds and pooled separate accounts	14.00%	18.00%
Short-term money market investments [Member] | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Allocation of investments in comingled funds and pooled separate accounts	1.00%	2.00%
Short-term money market investments [Member] | Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Share Price	$ 1
U.S. governmental and U.S. agency securities [Member] | Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Allocation of investments in mutual funds	12.00%	16.00%
Corporate Bonds | Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
Allocation of investments in comingled funds	20.00%	16.00%

Pension and Other Post-retire77

Pension and Other Post-retirement Benefit Plans (Changes in Fair Value Level 3 Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair Value of plan assets at beginning of year	$ 27.7	$ 23.8
Assets still held at year end	0.2	3.9
Assets sold during the year	1.9
Purchase, sales and settlements	(7.4)
Fair value of plan assets at end of year	$ 22.4	$ 27.7

Pension and Other Post-retire78

Pension and Other Post-retirement Benefit Plans (Expected Benefit Payments) (Details) $ in Millions	Sep. 30, 2016USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
2,017	$ 51.8
2,018	52.6
2,019	54.2
2,020	55.3
2,021	58.1
2022-2026	287.6
Health and Life Benefits
Defined Benefit Plan Disclosure [Line Items]
2,017	17
2,018	16.5
2,019	16.8
2,020	16.8
2,021	16.8
2022-2026	$ 84.1

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense		$ 11,500	$ 15,500	$ 3,400
Tax benefit from compensation expense		4,600	6,200	1,300
Unrecognized compensation expense		$ 11,700
Weighted-average period remaining to recognize unrecognized compensation expense		1 year 8 months
Accounts payable and other accrued liabilities-other		$ 18,000	16,400
Deferred Credits-other		$ 118,287	108,124
Stock options outstanding		0
Satisfaction of a performance condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Price		$ 57.67
Omnibus Plan (2016 plan)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issue under plan		2,197,546
Omnibus incentive plan (2007 plan)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issue under plan					1,700,000
Performances Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense		$ 5,100
Intrinsic Value Performance Shares Vested		$ 9,200	0	2,200
Shares granted during the period	[1]	89,328
Weighted-average grant date fair value, vested		$ 43.29
Fair value of shares expected to vest		$ 14,200
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense		6,600
Fair value of units expected to vest		20,200
Cash To Settle Performance Unit Awards		$ 6,400	0
Shares granted during the period		5,152,000
Liability for Equity Option Awards Outstanding		$ 13,600	13,300
Accounts payable and other accrued liabilities-other		6,900	6,400
Deferred Credits-other		$ 6,700	6,900
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash received from stock options exercised			$ 200	700
Tax benefit realized from exercised stock options				100
Stock options exercised			5,318
Stock options outstanding		0	0
Directors Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issue under plan		270,000
Allocated Share-based Compensation Expense		$ 800	$ 800	700
Tax benefit from compensation expense		$ 300	$ 300	$ 300
Shares granted during the period		13,000	15,100	17,000
Weighted-average grant date fair value, vested		$ 62.99	$ 54.05	$ 40.06
[1]	The number of common shares issued related to 248,394 non-vested performance shares outstanding at year-end may range from zero to 200 percent of this number based on our satisfaction of the market condition for total shareholder return relative to a selected peer group of companies. For 43,785 non-vested performance shares outstanding at year-end, the number of common shares issued may range from zero to 100% of this number based on our satisfaction of the performance condition for non-GAAP diluted earnings per share as compared to dividends paid per share.

Stock-Based Compensation (Tab80

Stock-Based Compensation (Table 1) (Details)	12 Months Ended
	Sep. 30, 2016$ / sharesshares
Performances Shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Non-vested and outstanding, beginning of year	304,089	[1]
Granted	89,328	[1]
Vested	(95,871)	[1]
Cancelled/Forfeited	(5,367)	[1]
Non-vested and outstanding, end of year	292,179	[1]
Weighted-average grant date fair value, non-vested and outstanding, beginning of year | $ / shares	$ 44.49
Weighted-average grant date fair value, granted | $ / shares	62.49
Weighted-average grant date fair value, vested | $ / shares	43.29
Weighted-average grant date fair value, cancelled/forfeited | $ / shares	50.63
Weighted-average grant date fair value, non-vested and outstanding, end of year | $ / shares	$ 50.28
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Non-vested and outstanding, beginning of year	12,685,633
Granted	5,152,000
Vested	(3,858,799)
Cancelled/Forfeited	(254,116)
Non-vested and outstanding, end of year	13,724,718
[1]	The number of common shares issued related to 248,394 non-vested performance shares outstanding at year-end may range from zero to 200 percent of this number based on our satisfaction of the market condition for total shareholder return relative to a selected peer group of companies. For 43,785 non-vested performance shares outstanding at year-end, the number of common shares issued may range from zero to 100% of this number based on our satisfaction of the performance condition for non-GAAP diluted earnings per share as compared to dividends paid per share.

Stock-Based Compensation (Tab81

Stock-Based Compensation (Table 2) (Details) - $ / shares		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Performances Shares
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted-average grant date fair value, granted		$ 62.49
Performances Shares | Satisfaction of market conditions
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected stock-price volatility	[1]	19.10%	18.30%	19.10%
Dividend yield	[2]	0.00%	4.18%	3.93%
Weighted-average grant date fair value, granted		$ 67.30	$ 44.44	$ 42.88
Performance Units | Grant 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected stock-price volatility		20.80%
Performance Units | Grant 2014
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected stock-price volatility		20.90%
[1]	Expected stock-price volatility is based on the daily historical volatility of our common shares for the past three fiscal years.
[2]	The dividend yield represents our annualized dividend yield on the closing market price of our common stock at the date of the grant. Performance shares granted in fiscal year 2016 accrue dividend equivalents and, therefore, this assumption is not used when determining the grant-date fair value.

Environmental Matters (Narrativ

Environmental Matters (Narrative) (Details) $ in Thousands		12 Months Ended
		Sep. 30, 2016USD ($)site	Sep. 30, 2015USD ($)
Site Contingency [Line Items]
Regulatory Assets, Noncurrent		$ 98,592	$ 80,018
Anacostia River Sediment Project | Minimum
Site Contingency [Line Items]
Study costs		15,000
Anacostia River Sediment Project | Maximum
Site Contingency [Line Items]
Study costs		20,000
Environmental response costs
Site Contingency [Line Items]
Regulatory Assets, Noncurrent	[1],[2]	$ 1,300	1,800
District of Columbia
Site Contingency [Line Items]
Recovery of environmental response costs term		3 years
Washington Gas Light Company
Site Contingency [Line Items]
Number of sites | site		10
Estimated maximum liability		$ 18,600	17,200
Regulatory Assets, Noncurrent		$ 98,527	79,946
Washington Gas Light Company | Reserve for Environmental Costs [Member]
Site Contingency [Line Items]
Number of sites | site		4
Accrual for environmental loss contingencies		$ 8,200	6,600
Washington Gas Light Company | Environmental response costs
Site Contingency [Line Items]
Regulatory Assets, Noncurrent		$ 1,300	$ 1,800
[1]	This balance represents allowed remediation expenditures at Washington Gas sites to be recovered through rates for Maryland and the District of Columbia. The recovery period is over several years.
[2]	Washington Gas does not earn its overall rate of return on these assets. Washington Gas is allowed to recover and required to pay, using short-term interest rates, the carrying costs related to billed gas costs due from and to its customers in the District of Columbia and Virginia jurisdictions.

Commitments and Contingencies83

Commitments and Contingencies (Narrative) (Details) $ in Millions	Nov. 02, 2016USD ($)	Sep. 30, 2016USD ($)company	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Aug. 26, 2016USD ($)	Aug. 05, 2014USD ($)
Commitments and Contingencies [Line Items]
Rent expense		$ 8.4	$ 6	$ 5.5
Number Of Service Agreements With Pipeline Companies | company		4
Subsequent Event
Commitments and Contingencies [Line Items]
Damages sought	$ 5
WGL Midstream
Commitments and Contingencies [Line Items]
Losses associated with contract pricing dispute		$ 15.2
WGL | Washington Gas Light Company | Guarantee on behalf of subsidiary
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation		30.7
WGL | WGL Energy Services | Guarantee on behalf of subsidiary
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation		212.6
WGL | WGL Energy Systems | Guarantee on behalf of subsidiary
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation		31.9
WGL | WGL Midstream | Guarantee on behalf of subsidiary
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation		321.1
WGL | Other subsidiaries | Guarantee on behalf of subsidiary
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation		2
WGL | External Partners | Performance Guarantee
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation		$ 18.9
Washington Gas Light Company
Commitments and Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss						$ 2.4
Regulatory proceeding adjustment			$ 2.4		$ 2.4

Committments and Contingencies

Committments and Contingencies - Tables (Details) $ in Millions	Sep. 30, 2016USD ($)
Minimum Payments Under Operating Leases
2,017	$ 7.5
2,018	7.5
2,019	3.9
2,020	3.7
2,021	3.4
Thereafter	27.8
Total	53.8
Washington Gas Light Company | Gas Purchase Committments
Contract Minimums
2,017	467.8	[1]
2,018	404.5	[1]
2,019	357.7	[1]
2,020	359.2	[1]
2,021	385.3	[1]
Thereafter	3,897.9	[1]
Total	5,872.4	[1]
Washington Gas Light Company | Pipeline Contracts
Contract Minimums
2,017	218.8	[2]
2,018	217.8	[2]
2,019	232.3	[2]
2,020	231.4	[2]
2,021	222.7	[2]
Thereafter	1,261	[2]
Total	2,384	[2]
WGL Energy Services | Gas Purchase Committments
Contract Minimums
2,017	148.8	[3]
2,018	40.1	[3]
2,019	16.7	[3]
2,020	7.5	[3]
2,021	0.4	[3]
Thereafter	0	[3]
Total	213.5	[3]
WGL Energy Services | Pipeline Contracts
Contract Minimums
2,017	3.2	[4]
2,018	1.5	[4]
2,019	0.8	[4]
2,020	0.5	[4]
2,021	0.4	[4]
Thereafter	0.8	[4]
Total	7.2	[4]
WGL Energy Services | Electric Purchase Commitments
Contract Minimums
2,017	413.1	[5]
2,018	179.6	[5]
2,019	78.2	[5]
2,020	30.2	[5]
2,021	1.7	[5]
Thereafter	0.9	[5]
Total	703.7	[5]
Commitments related to renewable energy credits	18.3
WGL Midstream | Gas Purchase Committments
Contract Minimums
2,017	464.5	[6]
2,018	1,077.6	[6]
2,019	1,512.2	[6]
2,020	1,641.2	[6]
2,021	1,622.4	[6]
Thereafter	27,780	[6]
Total	34,097.9	[6]
WGL Midstream | Pipeline Contracts
Contract Minimums
2,017	25	[4]
2,018	19.5	[4]
2,019	63.1	[4]
2,020	66.7	[4]
2,021	65.5	[4]
Thereafter	972	[4]
Total	1,211.8	[4]
Non Utility Total
Contract Minimums
2,017	1,054.6
2,018	1,318.3
2,019	1,671
2,020	1,746.1
2,021	1,690.4
Thereafter	28,753.7
Total	$ 36,234.1
[1]	Includes known and reasonably likely commitments to purchase natural gas. Cost estimates are based on forward market prices at September 30, 2016.
[2]	Represents minimum payments for natural gas transportation, storage and peaking contracts that have expiration dates through fiscal year 2034.
[3]	Represents fixed price commitments with city gate equivalent deliveries.
[4]	Represents minimum payments for natural gas transportation and storage contracts that have expiration dates through fiscal year 2044.
[5]	Represents electric purchase commitments that are based on existing fixed price and fixed volume contracts. Includes $18.3 million of commitments related to renewable energy credits.
[6]	Includes known and reasonably likely commitments to purchase natural gas. Cost estimates are based on forward market prices as of September 30, 2016. Certain of our gas purchase agreements have optionality, which may cause increases in these commitments.

Derivative and Weather Relate85

Derivative and Weather Related Instruments (Details) kWh in Millions, MMBTU in Millions		12 Months Ended
		Sep. 30, 2016USD ($)MMBTUkWh	Sep. 30, 2015USD ($)MMBTUkWh	Sep. 30, 2014USD ($)	May 10, 2016USD ($)
Asset Optimization [Abstract]
Gain (Loss) on Asset Optimization Transactions Net Pretax		$ 43,800,000	$ 27,900,000	$ (35,400,000)
Unrealized Gains (Loss) On Asset Optimization Derivative Instruments Net Pretax		12,000,000	(6,300,000)	$ (66,200,000)
Absolute Notional Amounts of Open Positions on Derivative Instruments
Interest Rate Swap		250,000,000	125,000,000
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		24,200,000	10,200,000
Total	[1]	(313,000,000)	(330,800,000)
Not Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		104,300,000	74,500,000
Gross Derivative Liabilities		(398,600,000)	(412,100,000)
Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		200,000
Gross Derivative Liabilities		(43,100,000)	(3,400,000)
Current assets- derivatives
Balance Sheet Classification of Derivative Instruments
Total	[1]	18,500,000	22,900,000
Current assets- derivatives | Not Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		24,000,000	29,700,000
Gross Derivative Liabilities		(5,500,000)	(6,800,000)
Non current assets- derivatives
Balance Sheet Classification of Derivative Instruments
Total	[1]	55,000,000	32,100,000
Non current assets- derivatives | Not Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		55,600,000	32,300,000
Gross Derivative Liabilities		(600,000)	(200,000)
Current liabilities- Derivatives
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		12,600,000	2,900,000
Total	[1]	(82,300,000)	(63,500,000)
Current liabilities- Derivatives | Not Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		18,300,000	9,800,000
Gross Derivative Liabilities		(113,200,000)	(76,200,000)
Non current liabilities- derivatives
Balance Sheet Classification of Derivative Instruments
Netting of Collateral		11,600,000	7,300,000
Total	[1]	(304,200,000)	(322,300,000)
Non current liabilities- derivatives | Not Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		6,400,000	2,700,000
Gross Derivative Liabilities		(279,300,000)	(328,900,000)
Non current liabilities- derivatives | Designated as Hedging Instrument [Member]
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets		200,000
Gross Derivative Liabilities		(43,100,000)	(3,400,000)
WGE Services
Derivative, Collateral [Abstract]
Right to Reclaim Cash		9,100,000	12,400,000
Collateral Already Posted Aggregate Fair Value		5,500,000	10,300,000
WGL Midstream
Derivative, Collateral [Abstract]
Right to Reclaim Cash		18,500,000	3,500,000
Derivative, Collateral, Obligation to Return Cash		$ 5,400,000	$ 400,000
Asset Optimization [Member]
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural Gas Derivative Transaction, Volume | MMBTU		2,108,450,000	2,082,920,000
Retail Sales [Member]
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural Gas Derivative Transaction, Volume | MMBTU		5,020,000	5,220,000
Electricity Derivative Transaction, Volume | kWh		4,377.5	4,292.7
Other Risk Management Activities [Member]
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural Gas Derivative Transaction, Volume | MMBTU		178,900,000	181,170,000
Electricity Derivative Transaction, Volume | kWh	[2]	21,070.4	19,965.7
WGL
Derivative, Collateral [Abstract]
Collateral Already Posted Aggregate Fair Value		$ 6,500,000	$ 0
WGL | Interest Rate Derivative
Absolute Notional Amounts of Open Positions on Derivative Instruments
Interest Rate Swap		250,000,000
Interest Rate Derivatives [Abstract]
Ineffectiveness of cash flow hedge		0
Washington Gas Light Company
Derivative, Collateral [Abstract]
Right to Reclaim Cash		4,300,000	3,500,000
Derivative, Collateral, Obligation to Return Cash		100,000	3,800,000
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[3]	39,800,000	20,400,000
Gross Derivative Liabilities	[3]	(297,200,000)	(306,200,000)
Total	[1],[3]	(257,400,000)	(285,800,000)
Washington Gas Light Company | Current assets- derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[3]	11,700,000	5,200,000
Gross Derivative Liabilities	[3]	(4,400,000)	(600,000)
Total	[1],[3]	7,300,000	4,600,000
Washington Gas Light Company | Non current assets- derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[3]	26,200,000	13,300,000
Gross Derivative Liabilities	[3]	(600,000)	(100,000)
Total	[1],[3]	25,600,000	13,200,000
Washington Gas Light Company | Current liabilities- Derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Assets	[3]	1,900,000	1,900,000
Gross Derivative Liabilities	[3]	(60,200,000)	(35,800,000)
Total	[1],[3]	(58,300,000)	(33,900,000)
Washington Gas Light Company | Non current liabilities- derivatives
Balance Sheet Classification of Derivative Instruments
Gross Derivative Liabilities	[3]	(232,000,000)	(269,700,000)
Total	[1],[3]	$ (232,000,000)	$ (269,700,000)
Washington Gas Light Company | Asset Optimization [Member]
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural Gas Derivative Transaction, Volume | MMBTU		1,272,500,000	1,331,670,000
Washington Gas Light Company | Other Risk Management Activities [Member]
Absolute Notional Amounts of Open Positions on Derivative Instruments
Natural Gas Derivative Transaction, Volume | MMBTU		130,900,000	138,180,000
Washington Gas Light Company | Interest Rate Derivative
Absolute Notional Amounts of Open Positions on Derivative Instruments
Interest Rate Swap		$ 0			$ 125,000,000
[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]	Comprised primarily of financial swaps, financial transmission rights and physical forward purchases.
[3]	Washington Gas did not have any derivative instruments outstanding that were designated as hedging instruments at September 30, 2016 or 2015.

Derivative and Weather Relate86

Derivative and Weather Related Instruments (Gains and Losses) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
Gains and (Losses) on Derivative Instruments
Recorded to other comprehensive income		$ (39,289)	[1]	$ (11,309)	[1]	$ (1,548)
Total		18,500		(17,200)		(244,900)
Operating Revenues Non Utility
Gains and (Losses) on Derivative Instruments
Recorded to income		5,800		71,300		(47,900)
Utility Cost Of Gas
Gains and (Losses) on Derivative Instruments
Recorded to income		12,100		(14,500)		(87,300)
Non Utility Cost Of Energy Related Sales
Gains and (Losses) on Derivative Instruments
Recorded to income		33,500		(43,700)		36,200
Other Income [Member]
Gains and (Losses) on Derivative Instruments
Recorded to income						(1,100)
Interest expense [Member]
Gains and (Losses) on Derivative Instruments
Recorded to income		(200)		(600)		(200)
Gas Costs [Member]
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		13,900		(18,400)		(143,300)
Other Regulatory Assets Liability [Member]
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities	[2]	(7,300)				200
Other Comprehensive Income (Loss) [Member]
Gains and (Losses) on Derivative Instruments
Recorded to other comprehensive income	[3]	(39,300)		(11,300)		(1,500)
Washington Gas Light Company
Gains and (Losses) on Derivative Instruments
Total		18,700		(32,900)		(230,400)
Washington Gas Light Company | Utility Cost Of Gas
Gains and (Losses) on Derivative Instruments
Recorded to income		12,100		(14,500)		(87,300)
Washington Gas Light Company | Gas Costs [Member]
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities		13,900		$ (18,400)		(143,300)
Washington Gas Light Company | Other Regulatory Assets Liability [Member]
Gains and (Losses) on Derivative Instruments
Recorded to regulatory assets/liabilities	[2]	$ (7,300)				$ 200
[1]	Cash flow hedging instruments represent interest rate swap agreements related to debt issuances. Refer to Note 14—Derivative and Weather-related Instruments for further discussion of the interest rate swap agreements.
[2]	Represents the settlement of Washington Gas' forward starting interest rate swap in September 2016.
[3]	Represents the effective portion of our cash flow hedges.

Derivative and Weather Relate87

Derivative and Weather Related Instruments (Details 2) $ in Millions	12 Months Ended
	Sep. 30, 2016USD ($)Counterparties	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
WGE Services
Derivative [Line Items]
Number of Counterparties | Counterparties	3
Percentage Of Credit Exposure	10.00%
Obligation to counterparties	$ 1
WGE Services | Weather Instruments
Derivative [Line Items]
Gain (losses) on weather related instruments, pretax	$ 1.7	$ 0.6	$ 3.4
WGL Midstream
Derivative [Line Items]
Number of Counterparties | Counterparties	1
Percentage Of Credit Exposure	10.00%
Obligation to counterparties	$ 26.9
WGL
Derivative [Line Items]
Derivative liabilities with credit-risk-contingent features	53.9	61.7
Maximum potential collateral requirements	41.4	54.6
Washington Gas Light Company
Derivative [Line Items]
Derivative liabilities with credit-risk-contingent features	11.3	18.9
Maximum potential collateral requirements	$ 11.3	$ 18.8
Number of Counterparties | Counterparties	2
Percentage Of Credit Exposure	10.00%
Obligation to counterparties	$ 36.6

Fair Value Measurements Under t

Fair Value Measurements Under the Fair Value Hierarchy (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	$ 104.5	$ 74.5
Liabilities	(441.7)	(415.5)
Natural Gas Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	82.8	51.2
Liabilities	(364.9)	(372.1)
Electricity Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	21.5	23.3
Liabilities	(33.7)	(40)
Interest Rate Derivative
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0.2
Liabilities	(43.1)	(3.4)
Level 2 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	29.6	24.7
Liabilities	(93.6)	(40)
Level 2 [Member] | Natural Gas Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	28.8	22.7
Liabilities	(46.7)	(33.9)
Level 2 [Member] | Electricity Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0.6	2
Liabilities	(3.8)	(2.7)
Level 2 [Member] | Interest Rate Derivative
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0.2
Liabilities	(43.1)	(3.4)
Level 3 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	74.9	49.8
Liabilities	(348.1)	(375.5)
Level 3 [Member] | Natural Gas Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	54	28.5
Liabilities	(318.2)	(338.2)
Level 3 [Member] | Electricity Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	20.9	21.3
Liabilities	(29.9)	(37.3)
Level 3 [Member] | Interest Rate Derivative
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0
Liabilities	0	0
Washington Gas Light Company
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	39.8	20.4
Liabilities	(297.2)	(306.2)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	39.8	20.4
Liabilities	(297.2)	(306.2)
Washington Gas Light Company | Level 1 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	0	0
Liabilities	0	0
Washington Gas Light Company | Level 1 [Member] | 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 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	15.4	6.9
Liabilities	(21.2)	(11.6)
Washington Gas Light Company | Level 2 [Member] | Natural Gas Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	15.4	6.9
Liabilities	(21.2)	(11.6)
Washington Gas Light Company | Level 3 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	24.4	13.5
Liabilities	(276)	(294.6)
Washington Gas Light Company | Level 3 [Member] | Natural Gas Related Derivatives
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Assets	24.4	13.5
Liabilities	$ (276)	$ (294.6)

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative information WGLH) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Oct. 01, 2015	Oct. 01, 2014
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ (273,200,000)	$ (325,700,000)	$ (325,700,000)	$ (299,700,000)
Natural Gas Related Derivatives
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(264,100,000)	(309,700,000)	(309,700,000)	(294,700,000)
Natural Gas Related Derivatives | Discounted Cash Flow
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(264,100,000)	(309,700,000)
Natural Gas Related Derivatives | Option Model
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(100,000)
Electricity Related Derivatives
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(9,100,000)	(16,000,000)	(16,000,000)	(5,000,000)
Electricity Related Derivatives | Discounted Cash Flow
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(9,100,000)	(16,000,000)
WGL | Natural Gas Related Derivatives | Discounted Cash Flow | Maximum | Natural Gas Basis Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	3.29	3.580
WGL | Natural Gas Related Derivatives | Discounted Cash Flow | Minimum | Natural Gas Basis Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	(2.021)	(1.441)
WGL | Natural Gas Related Derivatives | Option Model | Maximum | Natural Gas Basis Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	$ 3.310	$ 2.950
Option Volatility Percentage	869.90%	867.00%
WGL | Natural Gas Related Derivatives | Option Model | Minimum | Natural Gas Basis Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	$ (2.105)	$ (1.283)
Option Volatility Percentage	25.50%	22.50%
WGL | Electricity Related Derivatives | Discounted Cash Flow | Maximum | Electricity Congestion Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	$ 68.70	$ 73.35
WGL | Electricity Related Derivatives | Discounted Cash Flow | Minimum | Electricity Congestion Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	(6.199)	(5.75)
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(251,600,000)	(281,100,000)	$ (281,100,000)	$ (270,600,000)
Washington Gas Light Company | Natural Gas Related Derivatives | Discounted Cash Flow
Fair Value Measurements Details [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(251,600,000)	(281,100,000)
Washington Gas Light Company | Natural Gas Related Derivatives | Discounted Cash Flow | Maximum | Natural Gas Basis Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	3.29	3.5
Washington Gas Light Company | Natural Gas Related Derivatives | Discounted Cash Flow | Minimum | Natural Gas Basis Price [Member]
Fair Value Measurements Details [Line Items]
Input Price	$ (2.021)	$ (1.441)

Fair Value Measurements (Reconc

Fair Value Measurements (Reconciliation with Level 3 Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Oct. 01, 2015	Oct. 01, 2014
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ (273.2)	$ (325.7)	$ (325.7)	$ (299.7)
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs
Recorded to Income	(3.1)	(63)
Recorded to regulatory assets - gas costs	4.2	(30.9)
Transfers into Level 3	(0.8)	5.4
Transfers out of Level 3	8.9	3.6
Purchases	(2.4)	10.5
Settlements	45.7	48.4
Natural Gas Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(264.1)	(309.7)	(309.7)	(294.7)
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs
Recorded to Income	18.3	(30.7)
Recorded to regulatory assets - gas costs	4.2	(30.9)
Transfers into Level 3	(0.8)	5.4
Transfers out of Level 3	8.9	3.6
Settlements	15	37.6
Electricity Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(9.1)	(16)	(16)	(5)
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs
Recorded to Income	(21.4)	(32.3)
Purchases	(2.4)	10.5
Settlements	30.7	10.8
Washington Gas Light Company | Natural Gas Related Derivatives
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(251.6)	(281.1)	$ (281.1)	$ (270.6)
Reconciliation of Fair Value Measurements Using Significant Level 3 Inputs
Recorded to Income	4	(25)
Recorded to regulatory assets - gas costs	4.2	(30.9)
Transfers into Level 3	(0.2)	5.4
Transfers out of Level 3	9	2.5
Settlements	$ 12.5	$ 37.5

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Sep. 30, 2015
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Commercial Paper		$ 331,385	$ 332,000
Washington Gas Light Company
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Commercial Paper		104,385	89,000
Project financing		62,400
Carrying Amount
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Money Market Funds	[1]	10,600	11,000
Other Short Term Investments	[1]	1,400	400
Commercial Paper	[2]	269,000	332,000
Project financing	[2]	62,400
Long-term debt	[3]	1,444,300	944,200
Carrying Amount | Washington Gas Light Company
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Money Market Funds	[1]	5,000	4,300
Other Short Term Investments	[1]	1,400	400
Commercial Paper	[2]	42,000	89,000
Project financing		62,400
Long-term debt	[3]	945,900	695,900
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Money Market Funds	[1]	10,600	11,000
Other Short Term Investments	[1]	1,400	400
Commercial Paper	[2]	269,000	332,000
Project financing	[2]	62,400
Long-term debt	[3]	1,641,900	1,057,900
Fair Value | Washington Gas Light Company
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Money Market Funds	[1]	5,000	4,300
Other Short Term Investments	[1]	1,400	400
Commercial Paper	[2]	42,000	89,000
Project financing		62,400
Long-term debt	[3]	$ 1,126,400	$ 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]	Includes adjustments for current maturities and unamortized discounts, as applicable.

Fair Value Measurements (Realiz

Fair Value Measurements (Realized and Unrealized Gains and Losses with Level 3 Measurements) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	$ (3.1)	$ (63)	$ (79.4)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	4.2	(30.9)
Total Unrealized Gains (Losses)	18.1	(57.2)	(176.7)
Natural Gas Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	18.3	(30.7)	(72.6)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	4.2	(30.9)
Total Unrealized Gains (Losses)	7.2	(40.6)	(171.8)
Electricity Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	(21.4)	(32.3)	(5.7)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Total Unrealized Gains (Losses)	10.9	(16.6)	(3.8)
Warrant
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income			(1.1)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Total Unrealized Gains (Losses)			(1.1)
Operating Revenues Non Utility
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	(18.3)	14.2	(24.4)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	7.6	22.9	(38.8)
Operating Revenues Non Utility | Natural Gas Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	8.2	(5.7)	(2.3)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	9.9	(2.2)	(5)
Operating Revenues Non Utility | Electricity Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	(26.5)	19.9	(22.1)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(2.3)	25.1	(33.8)
Utility Cost Of Gas
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	4	(25)	(69.4)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	0.3	(15.8)	(60.6)
Utility Cost Of Gas | Natural Gas Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	4	(25)	(69.4)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	0.3	(15.8)	(60.6)
Utility Cost Of Gas | Electricity Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	0
Other income-net
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income			(1.1)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income			(1.1)
Other income-net | Warrant
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income			(1.1)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income			(1.1)
Non Utility Cost Of Energy Related Sales
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	11.2	(52.2)	15.5
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	12.8	(43.4)	33.7
Non Utility Cost Of Energy Related Sales | Natural Gas Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	6.1		(0.9)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	(0.4)	(1.7)	3.7
Non Utility Cost Of Energy Related Sales | Electricity Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	5.1	(52.2)	16.4
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	13.2	(41.7)	30
Regulatory asset-gas costs member
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	(2.6)	(20.9)	(109.9)
Regulatory asset-gas costs member | Natural Gas Related Derivatives
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	(2.6)	(20.9)	(109.9)
Washington Gas Light Company | Natural Gas Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	4	(25)	(69.4)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	4.2	(30.9)
Total Unrealized Gains (Losses)	(2.3)	(36.7)	(170.5)
Washington Gas Light Company | Utility Cost Of Gas | Natural Gas Related Derivatives
Realized and Unrealized Gains (Losses) Recorded to Income for Level 3 Measurements
Recorded to income	4	(25)	(69.4)
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to income	0.3	(15.8)	(60.6)
Washington Gas Light Company | Regulatory asset-gas costs member | Natural Gas Related Derivatives
Unrealized Gains (Losses) Recorded for Level 3 Measurements
Recorded to regulatory assets - gas costs	$ (2.6)	$ (20.9)	$ (109.9)

Fair Value Measurements (Nonrec

Fair Value Measurements (Nonrecurring Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Fair Value Measurements [Line Items]
Value of investment in direct financing leases	$ 29,780	$ 35,234
Impairment loss	4,110	5,625	$ 2,639
Springfield Operations Center
Fair Value Measurements [Line Items]
Impairment loss			800
Washington Gas Light Company
Fair Value Measurements [Line Items]
Impairment loss	0	0	$ 2,639
Washington Gas Light Company | Springfield Operations Center
Fair Value Measurements [Line Items]
Carrying Amount Of Long Lived Assets Held For Use		22,300
Fair Value Of Long Lived Assets Held For Use		21,500
Impairment loss		800
Washington Gas Light Company | Abandoned LNG Facility
Fair Value Measurements [Line Items]
Impairment loss		1,900
Washington Gas Resources
Fair Value Measurements [Line Items]
Impairment loss, cost-method investment		$ 5,600
Washington Gas Resources | Nextility
Fair Value Measurements [Line Items]
Lease Impairment	4,100
Value of investment in direct financing leases	$ 900

Operating Segment Reporting (De

Operating Segment Reporting (Details) $ in Thousands		12 Months Ended
		Sep. 30, 2016USD ($)segment		Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment		4
Operating revenues	[1]	$ 2,349,559		$ 2,659,830	$ 2,780,947
Operating revenues, regulated utility		1,044,117		1,303,044	1,416,951
Operating revenues, non-utility		1,305,442		1,356,786	1,363,996
Depreciation and amortization, regulated utility		132,566		121,892	110,772
Depreciation and amortization		132,566		121,892	110,772
Equity in earnings of unconsolidated affiliates		13,806		5,468	3,194
EBIT		319,298		266,894	202,252
Total Assets		6,058,705		5,261,359	4,829,835
Capital Expenditures		530,385		464,291	394,762
Equity Method Investments		303,491		136,884	94,902
Retail energy-marketing
Segment Reporting Information [Line Items]
Operating revenues, non-utility	[1]	1,238,480		1,306,758	1,310,279
Depreciation and amortization		1,154		671	756
Equity in earnings of unconsolidated affiliates		0		0	1
EBIT		64,968		46,629	14,015
Total Assets		486,778		463,141	388,651
Capital Expenditures		8,104		28	76
Equity Method Investments		0		0	0
Commercial energy systems
Segment Reporting Information [Line Items]
Operating revenues, non-utility	[1]	89,072	[2]	51,813	40,679
Depreciation and amortization		15,201	[2]	10,733	6,178
Equity in earnings of unconsolidated affiliates		7,620	[2]	2,095	1,953
EBIT		21,992	[2]	9,688	6,863
Total Assets		885,734	[2]	689,910	521,049
Capital Expenditures		128,780	[2]	136,749	108,363
Equity Method Investments		66,100	[2]	63,521	66,810
WGL Midstream
Segment Reporting Information [Line Items]
Operating revenues, non-utility	[1]	6,619		3,191	16,555
Depreciation and amortization		107		129	124
Equity in earnings of unconsolidated affiliates		6,186		2,623	771
EBIT		7,807		(2,720)	8,412
Total Assets		485,099		237,839	209,682
Capital Expenditures		0		85	0
Equity Method Investments		237,391		73,363	28,076
Other Activities
Segment Reporting Information [Line Items]
Operating revenues, non-utility	[1]	0		0	0
Depreciation and amortization		0		0	0
Equity in earnings of unconsolidated affiliates		0		750	469
EBIT		(3,184)		(9,667)	(11,539)
Total Assets		276,117		199,061	369,816
Capital Expenditures		0		0	0
Equity Method Investments		0		0	16
Eliminations
Segment Reporting Information [Line Items]
Operating revenues, non-utility	[1],[3]	(55,516)		(30,123)	(30,366)
Depreciation and amortization	[3]	(25)		(57)	(350)
Equity in earnings of unconsolidated affiliates	[3]	0		0	0
EBIT	[3]	(504)		(1,013)	(167)
Total Assets	[3]	(718,853)		(557,405)	(615,934)
Capital Expenditures	[3]	0		0	0
Equity Method Investments	[3]	0		0	0
Regulated Utility
Segment Reporting Information [Line Items]
Operating revenues, regulated utility	[1]	1,070,904		1,328,191	1,443,800
Depreciation and amortization, regulated utility		116,129		110,416	104,064
Equity in earnings of unconsolidated affiliates		0		0	0
EBIT		228,219		223,977	184,668
Total Assets		4,643,830		4,228,813	3,956,571
Capital Expenditures		393,501		327,429	286,323
Equity Method Investments		$ 0		$ 0	$ 0
[1]	Operating revenues are reported gross of revenue taxes. Revenue taxes of both the regulated utility and the retail energy-marketing segments include gross receipt taxes. Revenue taxes of the regulated utility segment also include public service commission fees, franchise fees and energy 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]	As of August 2016, Commercial energy systems' operating revenues include revenues from non-controlling interest. Commercial energy systems' EBIT is adjusted for the effects of non-controlling interest.
[3]	Intersegment eliminations include any mark-to market valuations associated with trading activities 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 Reporting (95

Operating Segment Reporting (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting [Abstract]
Total consolidated EBIT	$ 319,298	$ 266,894	$ 202,252
Interest Expense	52,310	50,511	37,738
Income tax expense	98,074	83,804	57,254
Dividends on Washington Gas Light Company preferred stock	1,320	1,320	1,320
Net income (loss) applicable to common stock	$ 167,594	$ 131,259	$ 105,940

Other Investments - Narratives

Other Investments - Narratives (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2016USD ($)miledekathermsBcfeinvestmentagreement	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Oct. 24, 2016USD ($)	Jun. 30, 2016	Mar. 31, 2015
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Number of investments that qualify as VIEs | investment	5
Equity in earnings of unconsolidated affiliates	$ 13,806	$ 5,468	$ 3,194
Funding provided per agreement	5,031	4,151	0
Investments in direct financing leases, capital leases	29,780	35,234
Investments in unconsolidated affiliates	303,491	136,884
Crab Run
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity in earnings of unconsolidated affiliates	700
WGL Midstream | Constitution
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Investment amount	$ 95,500
Equity Method Investment Ownership Percentage	10.00%
Maximum exposure to loss	$ 35,200
Investments in unconsolidated affiliates	$ 38,600	33,100
WGL Midstream | Meade
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity Method Investment Ownership Percentage	55.00%
Pipeline length in miles | mile	185
Transportation and delivery | dekatherms	1,700,000
Maximum Loss Exposure	$ 80,100
Estimated Investment in Meade	410,000
Investments in unconsolidated affiliates	$ 80,800	30,500
WGL Midstream | Mountain Valley Pipeline
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity Method Investment Ownership Percentage						7.00%
Transportation and delivery | dekatherms	2,000,000
Investments in unconsolidated affiliates	$ 22,500	9,800
WGL Midstream | Mountain Valley Pipeline | Subsequent Event
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity Method Investment Ownership Percentage				3.00%
Estimated Investment in Mountain Valley Pipeline				$ 326,400
WGL Midstream | Mountain Valley Pipeline | Guarantee on behalf of subsidiary
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Funding provided per agreement	11,700
WGL Midstream | Mountain Valley Pipeline | Maximum | Subsequent Event
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity Method Investment Ownership Percentage				10.00%
WGL Midstream | Stonewall
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity Method Investment Difference Between Carrying Amount and Underlying Equity	$ 9,100
Equity Method Investment Ownership Percentage	35.00%
Investment in Stonewall System	$ 89,400
Pipeline gathering capacity | Bcfe	1.4
Expected decrease in equity method investment ownership percentage					30.00%
Investments in unconsolidated affiliates	$ 95,500
WGSW | SunEdison and Nextility
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Investments in direct financing leases, capital leases	30,900	37,200
Net Investment in Direct Financing Lease, Current	1,100	2,000
Investment Tax Credit	$ 13,300	14,700
Number of Energy Related Agreements | agreement	2
WGSW | Nextility
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Lease Impairment	$ 4,100
WGSW | ASD
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Equity Method Investment Difference Between Carrying Amount and Underlying Equity	35,800
Maximum Loss Exposure	72,600
Investments in unconsolidated affiliates	66,100	63,500
WGSW | SFGF
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Interest in tax equity partnership	2,300
Contributions to tax equity partnership	1,700
Washington Gas Resources
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Impairment loss, cost-method investment		5,600
Washington Gas Resources | Nextility
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Investments in direct financing leases, capital leases	900
Lease Impairment	$ 4,100
Washington Gas Resources | ASDHI
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Cost Method Investments			$ 5,600
Impairment loss, cost-method investment		$ 5,600
VIE, Not Primary Beneficiary
Summary Of Investments Other Than Investments In Related Parties Reportable Data [Line Items]
Variable Interest Entity, Number of Investments | investment	4

Other Investments - Financing L

Other Investments - Financing Leases Table (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2012
Capital Leases, Future Minimum Payments Receivable, Fiscal Year Maturity [Abstract]
2,017	$ 2.2
2,018	2.2
2,019	2.1
2,020	2.2
2,021	2.2
Thereafter	28.5
Total	39.4
Direct Financing Leases - Residual Value	9.7
Direct Financing Leases - Tax Credits	4.5
Direct Financing Leases - Unearned Income	$ 18.6
Direct Financing Leases - Initial Direct Costs		$ 0.7

Other Investments - Location Ta

Other Investments - Location Table (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Assets
Investments in unconsolidated affiliates		$ 303,491	$ 136,884
Property, Plant and Equipment		5,542,916	5,003,910
Investments in direct financing leases, capital leases		29,780	35,234
Liabilities
Accrued liabilities		726,763	672,963
Income Statement
Equity in earnings of unconsolidated affiliates		13,806	5,468	$ 3,194
Operation and Maintenance Expenses		401,776	395,770	365,873
Non-controlling interest		(550)	0	0
Non-consolidated VIE's | Solar Investments
Assets
Investments in unconsolidated affiliates		66,100	63,500
Investments in direct financing leases, capital leases		29,800	35,200
Accounts Receivable		1,100	2,000
Total assets		97,000	100,700
Income Statement
Equity in earnings of unconsolidated affiliates		7,600	2,100	2,000
Depreciation and amortization		300	300	200
Operation and Maintenance Expenses		4,100
Other income (expenses) - net		3,100
Other income - net			3,200	2,600
Non-consolidated VIE's | Pipelines
Assets
Investments in unconsolidated affiliates		80,800	30,500
Total assets		80,800	30,500
Income Statement
Equity in earnings of unconsolidated affiliates		(100)	100	300
Non-consolidated VIE's | Other
Income Statement
Non-controlling interest			700	(100)
Consolidated VIE's | Solar Investments
Assets
Property, Plant and Equipment		6,500
Construction in Progress		6,700
Total assets		13,200
Income Statement
Non-controlling interest		(600)
Non-consolidated Non VIE's | Pipelines
Assets
Investments in unconsolidated affiliates		156,600	42,900
Accounts Receivable	[1]	9,200	4,200
Total assets		165,800	47,100
Income Statement
Equity in earnings of unconsolidated affiliates		6,300	2,600	1,000
Other income (expenses) - net		(100)
Non-consolidated Non VIE's | Other
Income Statement
Other income (expenses) - net			(5,600)
Total
Assets
Investments in unconsolidated affiliates		303,500	136,900
Property, Plant and Equipment		6,500
Construction in Progress		6,700
Investments in direct financing leases, capital leases		29,800	35,200
Accounts Receivable		10,300	6,200
Income Statement
Equity in earnings of unconsolidated affiliates		13,800	5,500	3,200
Depreciation and amortization		300	300	200
Operation and Maintenance Expenses		4,100
Other income (expenses) - net			(2,400)
Non-controlling interest		(600)
Other income - net		3,000		$ 2,600
Total | Total assets
Schedule of Investments [Line Items]
Investments		$ 356,800	$ 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.

Related Party Transactions (Det

Related Party Transactions (Details) $ in Thousands	Apr. 01, 2016USD ($)MMBTU$ / dekatherm	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Related Party Transaction [Line Items]
Gas balancing service charge		$ 26,800	$ 25,100	$ 26,600
Washington Gas Light Company
Related Party Transaction [Line Items]
Receivables from Associated Companies		13,799	3,176
Payables to Associated Companies		65,770	68,623
Gas Volume in dekatherms | MMBTU	723,706
Price of gas | $ / dekatherm	0.594
Cash received for the value of the right to purchase base gas	$ 900
WGL Energy Services
Related Party Transaction [Line Items]
Related Party Gas Imbalance Payable		800	500
WGL Energy Services | Washington Gas Light Company
Related Party Transaction [Line Items]
Related Party Purchased Receivables		$ 4,200	$ 6,600

Accumulated Other Comprehens100

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2014
AOCI, Net of Tax [Roll Forward]
Beginning Balance		$ (14,236)		$ (7,961)
Qualified cash flow hedging instruments		(39,289)	[1]	(11,309)	[1]	$ (1,548)
Change in prior service cost	$ (26,100)	(891)	[2]	696	[2]	6,095
Amortization of actuarial gain (loss)		(936)	[2]	(1,195)	[2]	1,594
Current-period other comprehensive income (loss)		(41,116)		(11,808)		6,141
Income tax expense related to other comprehensive income (loss)		(16,813)		(5,533)		3,054
Ending Balance	(14,236)	(38,539)		(14,236)		(7,961)
Washington Gas Light Company
AOCI, Net of Tax [Roll Forward]
Beginning Balance		(6,712)		(6,413)
Change in prior service cost		(891)	[3]	696	[3]	6,095
Amortization of actuarial gain (loss)		(936)	[3]	(1,195)	[3]	1,594
Current-period other comprehensive income (loss)		(1,827)		(499)
Income tax expense related to other comprehensive income (loss)		(709)		(200)		3,054
Ending Balance	$ (6,712)	$ (7,830)		$ (6,712)		$ (6,413)
[1]	Cash flow hedging instruments represent interest rate swap agreements related to debt issuances. Refer to Note 14—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 10—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 10—Pension and other post-retirement benefit plans for additional details.

Quarterly Financial Data - Tabl

Quarterly Financial Data - Table (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended														12 Months Ended
		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015	Dec. 31, 2014		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Operating revenues	[1]															$ 2,349,559	$ 2,659,830	$ 2,780,947
Operating income (loss)																300,296	260,773	197,522
Net income (loss)																168,364	132,579	107,260
Net income (loss) applicable to common stock																$ 167,594	$ 131,259	$ 105,940
Earnings (loss) per average share of common stock:
Basic																$ 3.33	$ 2.64	$ 2.05
Diluted																$ 3.31	$ 2.62	$ 2.05
WGL
Operating revenues		$ 459,899	[2]	$ 440,587	[3]	$ 835,689	$ 613,384	[4]	$ 467,687	[2]	$ 441,173	[3]	$ 1,001,733	$ 749,237	[4]
Operating income (loss)		(5,307)	[2]	13,683	[3]	174,411	117,509	[4]	13,612	[2]	(17,567)	[3]	142,886	121,842	[4]
Net income (loss)		(9,110)		2,355		106,618	68,501		1,936		(15,360)		81,785	64,218
Net income (loss) applicable to common stock		$ (8,890)	[2]	$ 2,025	[3]	$ 106,288	$ 68,171	[4]	$ 1,606	[2]	$ (15,690)	[3]	$ 81,455	$ 63,888	[4]
Earnings (loss) per average share of common stock:
Basic		$ (0.17)	[2]	$ 0.04	[3]	$ 2.13	$ 1.37	[4]	$ 0.03	[2]	$ (0.32)	[3]	$ 1.64	$ 1.28	[4]
Diluted		$ (0.17)	[2]	$ 0.04	[3]	$ 2.11	$ 1.36	[4]	$ 0.03	[2]	$ (0.32)	[3]	$ 1.63	$ 1.28	[4]
Washington Gas Light Company
Operating revenues		$ 136,557	[2]	$ 187,077	[3]	$ 452,024	$ 295,246	[4]	$ 134,959	[2]	$ 190,345	[3]	$ 615,694	$ 387,193	[4]	$ 1,070,904	$ 1,328,191	$ 1,443,800
Operating income (loss)		(14,308)	[2]	(20,528)	[3]	164,226	98,977	[4]	(15,454)	[2]	(6,729)	[3]	129,944	114,623	[4]	228,367	222,384	182,123
Net income (loss)		(17,412)		(18,519)		94,433	54,612	[4]	(19,543)		(11,424)		74,694	64,951	[4]	113,114	108,678	98,324
Net income (loss) applicable to common stock		$ (17,742)	[2]	$ (18,849)	[3]	$ 94,103	$ 54,282	[4]	$ (19,873)	[2]	$ (11,754)	[3]	$ 74,364	$ 64,621	[4]	$ 111,794	$ 107,358	$ 97,004
[1]	Operating revenues are reported gross of revenue taxes. Revenue taxes of both the regulated utility and the retail energy-marketing segments include gross receipt taxes. Revenue taxes of the regulated utility segment also include public service commission fees, franchise fees and energy 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]	) During the fourth quarter of fiscal year 2016, WGL recorded an additional impairment charge of $1.1 million related to its investment in direct financing leases from Nextility and $1.7 million in proceeds from an environmental insurance policy. During the fourth quarter of fiscal year 2015, Washington Gas recorded a one-time adjustment of $2.4 million as a result of charges associated with a regulatory proceeding. Refer to Note 1—Accounting Policies of the Notes to Consolidated Financial Statements for further discussion of the impairments, to Note 13— Commitments and Contingencies for further discussion of the Antero Contract and WGL Holdings, Inc Results of Operations for further discussion of the net proceeds related to the environmental insurance policy.
[3]	During the third quarter of fiscal year 2016, WGL recorded an impairment charge of $3.0 million related to its investment in direct financing leases from Nextility. During the third quarter of fiscal year 2015, WGL recorded a $3.0 million liability for unrecovered government contracting costs under the Small Business Administration Development 8(a) Program and Washington Gas recorded approximately $0.5 million in transaction fees related to the sale of its Springfield Operations Center. Refer to Note 1—Accounting Policies of the Notes to Consolidated Financial Statements for further discussion of the impairments and to Note 13— Commitments and Contingencies for further discussion of the Antero Contract.
[4]	During the fist quarter of fiscal year 2016, there were no substantial variations in operations. During the first quarter of fiscal year 2015, WGL recorded an impairment charge of $5.6 million related to its investment in ASDHI.

Quarterly Financial Information

Quarterly Financial Information - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Aug. 26, 2016	Jun. 30, 2016
WGL
Impairment loss, cost-method investment				$ 5.6
Lease Impairment			$ 4.1
Un-recovered government contracting costs	$ 3
Proceeds from environmental insurance policy			1.7
WGL | ASDHI
Impairment loss, cost-method investment		$ 5.6
WGL | Nextility
Lease Impairment			$ 1.1			$ 3
Washington Gas Light Company
Regulatory proceeding adjustment				$ 2.4	$ 2.4
Springfield Operations Center | Washington Gas Light Company
Impairment	$ 0.5

Schedule II (Details)

Schedule II (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Beginning Balance		$ 26,224	$ 23,341	$ 20,433
Valuation Allowances and Reserves, Charged to Cost and Expense		13,051	18,250	15,874
Valuation Allowances and Reserves, Charged to Other Accounts	[1]	3,856	4,789	4,341
Valuation Allowances and Reserves, Deductions	[2]	15,792	20,156	17,307
Valuation Allowances and Reserves, Ending Balance		27,339	26,224	23,341
Washington Gas Light Company
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Beginning Balance		19,254	19,209	17,498
Valuation Allowances and Reserves, Charged to Cost and Expense		10,946	12,800	12,004
Valuation Allowances and Reserves, Charged to Other Accounts	[3]	3,806	4,686	4,198
Valuation Allowances and Reserves, Deductions	[4]	13,786	17,441	14,491
Valuation Allowances and Reserves, Ending Balance		$ 20,220	$ 19,254	$ 19,209
[1]	Recoveries on receivables previously written off as uncollectible and unclaimed customer deposits, overpayments, etc., not refundable.
[2]	Includes deductions for purposes for which reserves were provided or revisions made of estimated exposure.
[3]	Recoveries on receivables previously written off as uncollectible and unclaimed customer deposits, overpayments, etc., not refundable.
[4]	Includes deductions for purposes for which reserves were provided or revisions made of estimated exposure.