Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	2019 Equity Distribution Agreement	2019 Underwriting Agreement	September 2020 Equity Distribution Agreement	November 2020 Equity Distribution Agreement	Stockholders' Equity	Stockholders' Equity 2019 Equity Distribution Agreement	Stockholders' Equity 2019 Underwriting Agreement	Stockholders' Equity September 2020 Equity Distribution Agreement	Stockholders' Equity November 2020 Equity Distribution Agreement	Additional Paid-In Capital	Additional Paid-In Capital 2019 Equity Distribution Agreement	Additional Paid-In Capital 2019 Underwriting Agreement	Additional Paid-In Capital September 2020 Equity Distribution Agreement	Additional Paid-In Capital November 2020 Equity Distribution Agreement	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit) Cumulative Effect, Period of Adoption, Adjustment	Fulgent Stockholders' Equity	Fulgent Stockholders' Equity Cumulative Effect, Period of Adoption, Adjustment	Fulgent Stockholders' Equity 2019 Equity Distribution Agreement	Fulgent Stockholders' Equity 2019 Underwriting Agreement	Fulgent Stockholders' Equity September 2020 Equity Distribution Agreement	Fulgent Stockholders' Equity November 2020 Equity Distribution Agreement	Noncontrolling Interest
Beginning Balance at Dec. 31, 2018	$ 51,152						$ 2					$ 114,203					$ (35)	$ (63,018)		$ 51,152
Beginning Balance, Shares at Dec. 31, 2018							18,172
Equity-based compensation	3,209											3,209								3,209
Exercise of common stock options	38											38								38
Exercise of common stock options, Shares							100
Restricted stock awards, Shares							434
Issuance of common stock			$ 979	$ 27,650									$ 979	$ 27,650								$ 979	$ 27,650
Issuance of common stock, Shares								104	2,674
Common stock withholding for employee tax obligations	(21)											(21)								(21)
Common stock withholding for employee tax obligations, Shares							(1)
Other comprehensive gain (loss), net	181																181			181
Net income (loss) from consolidated operations	(411)																	(411)		(411)
Ending Balance at Dec. 31, 2019	82,777						$ 2					146,058					146	(63,429)		82,777
Ending Balance, Shares at Dec. 31, 2019							21,483
Equity-based compensation	8,157											8,157								8,157
Exercise of common stock options	104											104								104
Exercise of common stock options, Shares							56
Restricted stock awards, Shares							655
Issuance of common stock			$ 42,655		$ 122,103	$ 99,051				$ 1			$ 42,655		$ 122,102	$ 99,051						$ 42,655		$ 122,103	$ 99,051
Issuance of common stock, Shares								1,108		2,846	2,034
Common stock withholding for employee tax obligations	(62)											(62)								(62)
Common stock withholding for employee tax obligations, Shares							(4)
Other comprehensive gain (loss), net	292																292			292
Net income (loss) from consolidated operations	214,310																	214,310		214,310
Ending Balance at Dec. 31, 2020	$ 569,387	$ (887)					$ 3					418,065					438	150,881	$ (887)	569,387	$ (887)
Ending Balance, Shares at Dec. 31, 2020	28,178						28,178
Equity-based compensation	$ 15,882											15,882								15,882
Exercise of common stock options	86											86								86
Exercise of common stock options, Shares							76
Restricted stock awards, Shares							836
Issuance of common stock						$ 72,030										$ 72,030									$ 72,030
Issuance of common stock, Shares											1,111
Common stock withholding for employee tax obligations	(4,155)											(4,155)								(4,155)
Common stock withholding for employee tax obligations, Shares							(41)
Cumulative tax effect of accounting change	239																	239		239
Noncontrolling interest assumed related to acquisitions	8,151																									$ 8,151
Other comprehensive gain (loss), net	(1,092)																(1,197)			(1,197)						105
Net income (loss) from consolidated operations	506,239																	507,364		507,364						(1,125)
Ending Balance at Dec. 31, 2021	$ 1,165,880						$ 3					$ 501,908					$ (759)	$ 657,597		$ 1,158,749						$ 7,131
Ending Balance, Shares at Dec. 31, 2021	30,160						30,160