Net Loss Per Share - Schedule of Potentially Dilutive Common Stock Equivalents Excluded From Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	59,273	50,503
Common stock warrants
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	36,783	26,724
Legacy GCT
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	20,000	20,000
Unvested RSUs
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	1,071	424
Sponsor Earnout Shares
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	571	1,920
Convertible promissory notes
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	500	767
Options issued and outstanding
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	348	668