CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Cash Flows [Abstract]
Available for sale securities transferred to held to maturity, net of unrealized loss	$ 13,186	$ 13,186	$ 13,186

Available for sale securities transferred to held to maturity, net of unrealized loss

No definition available.

Name:	gnty_AvailableForSaleSecuritiesTransferredToHeldToMaturityNetOfUnrealizedLoss
Namespace Prefix:	gnty_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration