Accrued Expenses and Other Current Liabilities - Additional Information (Details) (USD $)	12 Months Ended
Sep. 30, 2013
Accrued Expenses and Other Current Liabilities (Textual) [Abstract]
Purchased stop-loss coverage for individual claims	$ 150,000

Minimum amount per claimant on which company purchased stop loss.

No definition available.

Name:	geos_MinimumAmountPerClaimantOnWhichCompanyPurchasedStopLoss
Namespace Prefix:	geos_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration