Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Dec. 21, 2018	Mar. 31, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	DEEP WELL OIL & GAS INC
Entity Central Index Key	0000869495
Trading Symbol	DWOG
Amendment Flag	false
Current Fiscal Year End Date	--09-30
Document Type	10-K
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Public Float			$ 2.5
Entity Common Stock Shares Outstanding		230,574,603