Significant Accounting Policies - Additional Information (Details) $ in Millions	Mar. 31, 2020 USD ($)
Accounting Policies [Abstract]
Cash and cash equivalents held by foreign subsidiaries and branch offices	$ 6.5

Cash and cash equivalents held by foreign subsidiaries.

No definition available.

Name:	geos_CashAndCashEquivalentsHeldByForeignSubsidiaries
Namespace Prefix:	geos_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant