CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (21,652)	$ (39,089)	$ (57,458)	$ (64,859)
Changes in foreign currency translation adjustments:
Change during period	(33)	61	66	34
Reclassification of adjustments to net loss due to dissolution of Personalis (Shanghai) Ltd				199
Net changes in foreign currency translation adjustments	(33)	61	66	233
Change in unrealized gain on available-for-sale debt securities	95	146	39	76
Comprehensive loss	$ (21,590)	$ (38,882)	$ (57,353)	$ (64,550)