Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 11, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Entity Registrant Name	ATRECA, INC.
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001532346
Amendment Flag	false
Entity Public Float			$ 210.9
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		22,136,897
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,934,191