Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Jul. 28, 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	ACAD
Entity Registrant Name	ACADIA PHARMACEUTICALS INC.
Entity Central Index Key	0001070494
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		161,843,185
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	000-50768
Entity Tax Identification Number	06-1376651
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Address, Address Line One	12830 El Camino Real, Suite 400
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	858
Local Phone Number	558-2871
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ