SHARE-BASED COMPENSATION - Schedule of Compensation Expenses Recognized (Details) - RSUs - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share compensation expenses	$ 11,159	$ 2,940	$ 11,419	$ 4,082
Income Statement Location [Axis]: us-gaap:GeneralAndAdministrativeExpense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share compensation expenses	7,354	1,602	7,459	2,172
Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share compensation expenses	397	310	457	566
Income Statement Location [Axis]: us-gaap:SellingAndMarketingExpense
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share compensation expenses	2,612	900	2,678	1,077
Income Statement Location [Axis]: gct:CostOfRevenues
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share compensation expenses	$ 796	$ 128	$ 825	$ 267