Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (384,770)	$ (246,283)	$ (67,851)
Other comprehensive income (loss), net of tax impact:
Unrealized (loss) gain on available-for-sale securities	(5,769)	1,131	1,110
Foreign currency translation adjustments	(1,692)	455	84
Other comprehensive income	(7,461)	1,586	1,194
Comprehensive loss	(392,231)	(244,697)	(66,657)
Comprehensive loss attributable to redeemable noncontrolling interest	(20,900)	(7,500)	(7,800)
Comprehensive loss attributable to Guardant Health, Inc.	$ (413,131)	$ (252,197)	$ (74,457)