Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Oct. 31, 2019	Mar. 29, 2019
Cover [Abstract]
Entity Registrant Name	GEOSPACE TECHNOLOGIES CORP
Entity Central Index Key	0001001115
Document Type	10-K
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Title of 12(b) Security	Common Stock
Trading Symbol	GEOS
Security Exchange Name	NASDAQ
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 Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Annual Report	true
Document Transition Report	false
Entity Public Float			$ 170
Entity Common Stock, Shares Outstanding		13,630,666
Entity Incorporation, State or Country Code	TX
Entity File Number	001-13601
Entity Tax Identification Number	76-0447780
Entity Address, Address Line One	7007 Pinemont Drive
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77040-6601
City Area Code	(713)
Local Phone Number	986-4444