Document And Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2020	Sep. 25, 2021	Mar. 31, 2020
Document Information Line Items
Entity Registrant Name	DEEP WELL OIL & GAS INC
Document Type	10-K
Current Fiscal Year End Date	--09-30
Entity Common Stock, Shares Outstanding		229,374,605
Entity Public Float			$ 1,708,373
Amendment Flag	false
Entity Central Index Key	0000869495
Entity Current Reporting Status	No
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Ex Transition Period	false
Entity Incorporation, State or Country Code	NV
Entity Interactive Data Current	No