Lessee operating lease lease not yet commenced minimum lease payments.

No definition available.

Name:	acad_LesseeOperatingLeaseLeaseNotYetCommencedMinimumLeasePayments
Namespace Prefix:	acad_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Area of land subject to a ground lease.

+ References

No definition available.

+ Details

Name:	us-gaap_LandSubjectToGroundLeases
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of lessee's operating lease that has not yet commenced. Including, but not limited to, nature of involvement with construction or design of underlying asset for lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LeaseArrangementTypeAxis=acad_CorporateOfficeSpaceLeaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Event - Additional Information (Detail) - Corporate Office Space Lease Agreement $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 24, 2020 USD ($) ft²	Dec. 31, 2018 USD ($)
Subsequent Event [Line Items]
Operating leases arrangement term			10 years 9 months
CALIFORNIA
Subsequent Event [Line Items]
Minimum lease payment amount			$ 53.7
Lease commencement period	third quarter of 2020
Subsequent Event
Subsequent Event [Line Items]
Operating leases arrangement term		10 years 7 months
Subsequent Event \| CALIFORNIA
Subsequent Event [Line Items]
Office space leases in square feet \| ft²		31,608
Minimum lease payment amount		$ 25.3