Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2019	Jul. 31, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	GEOS
Entity Registrant Name	GEOSPACE TECHNOLOGIES CORP
Entity Central Index Key	0001001115
Current Fiscal Year End Date	--09-30
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,631,041
Entity Current Reporting Status	Yes
Entity File Number	001-13601
Entity Tax Identification Number	760447780
Entity Address, Address Line One	7007 Pinemont
Entity Address, City or Town	Houston
Entity Address, State or Province	Texas
Entity Address, Postal Zip Code	77040
City Area Code	(713)
Local Phone Number	986-4444