Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income from consolidated operations	$ 122,224	$ 46,638	$ 402,562	$ 48,003
Other comprehensive income (loss):
Foreign currency translation gain (loss)	(114)	18	(78)	17
Net unrealized gain (loss) on marketable securities, net of tax	142	(460)	(587)	444
Comprehensive income from consolidated operations	122,252	46,196	401,897	48,464
Net loss attributable to noncontrolling interests	298		463
Foreign currency translation loss attributable to noncontrolling interest	25		15
Comprehensive loss attributable to noncontrolling interest	323		478
Comprehensive income attributable to Fulgent	$ 122,575	$ 46,196	$ 402,375	$ 48,464