Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (479,449)	$ (654,588)	$ (384,770)
Other comprehensive income (loss), net of tax impact:
Unrealized gain (loss) on available-for-sale securities	16,758	(13,158)	(5,769)
Foreign currency translation adjustments	(911)	(1,600)	(1,692)
Other comprehensive income (loss)	15,847	(14,758)	(7,461)
Comprehensive loss	(463,602)	(669,346)	(392,231)
Comprehensive loss attributable to redeemable noncontrolling interest	0	0	(20,900)
Comprehensive loss attributable to Guardant Health, Inc. common stockholders	$ (463,602)	$ (669,346)	$ (413,131)