v3.10.0.1

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Sep. 30, 2018	Nov. 29, 2018	Mar. 31, 2018
Document Information [Line Items]
Entity Registrant Name	WGL Holdings Inc.
Entity Central Index Key	0001103601
Document Type	10-K/A
Document Period End Date	Sep. 30, 2018
Amendment Flag	true
Document Fiscal Year Focus	2018
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
Entity Public Float			$ 4,250,758,369
Entity Common Stock, Shares Outstanding		100
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Amendment Description	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:6px;text-indent:12px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">WGL Holdings, Inc. (WGL) and Washington Gas Light Company (Washington Gas) are filing this Amendment No. 1 (“Form 10-K/A”) to their Annual Report on Form 10-K (“Form 10-K”) for the fiscal year ended September 30, 2018 filed with the Securities and Exchange Commission on November 20, 2018, solely to amend Exhibit 23, the Consent of Deloitte & Touche LLP. The companies are amending their Form 10-K filing due to a typographical error with respect to the date contained in the consent included in the original filing, which referenced the incorrect date of the audit opinion. There are no other changes to the Form 10-K or the consent.</font></div></div>

Description of changes contained within amended document.

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WGL HOLDINGS INC 10-K/A