Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Oct. 31, 2018	Mar. 29, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	GEOSPACE TECHNOLOGIES CORP
Entity Central Index Key	0001001115
Document Type	10-K
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Trading Symbol	GEOS
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	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 129
Entity Common Stock, Shares Outstanding		13,600,541