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v3.23.4

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract] |  |
Accrued termination and cancellation charges | $ 0 | $ 0
Royalty payment due | $ 0 | $ 0

X
- Definition Accrued termination and cancellation charges. + References No definition available. + Details
Name: | grph_AccruedTerminationAndCancellationCharges
Namespace Prefix: | grph_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Royalty payment due. + References No definition available. + Details
Name: | grph_RoyaltyPaymentDue
Namespace Prefix: | grph_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration