Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 01, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Trading Symbol	FLGT
Entity Registrant Name	FULGENT GENETICS, INC.
Entity Central Index Key	0001674930
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		30,265,754
Entity File Number	001-37894
Entity Tax Identification Number	81-2621304
Entity Address, Address Line One	4978 Santa Anita Avenue
Entity Address, City or Town	Temple City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91780
City Area Code	626
Local Phone Number	350-0537
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE