Commitments and Contingencies	12 Months Ended
Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Royalty Payments Pursuant to the terms of its 2006 license agreement with the Ipsen Group, the Company is required to make royalty payments of two percent of net sales of NUPLAZID. License Agreements In May 2018, the Company signed an Exclusivity Deed (the “Deed”) with Neuren Pharmaceuticals Limited (“Neuren”) that provided for exclusive negotiations for a period of three months from the date of the Deed. Under the terms of the Deed, the Company invested $3.1 million to subscribe for 1,330,000 shares of Neuren and paid $0.9 million for the exclusive right to negotiate a deal with Neuren, which was recorded in selling, general and administrative expenses in the Consolidated Statements of Operations in the second quarter of 2018. At December 31, 2019, the Company continues to hold the equity securities as a strategic investment in which the Company does not have a controlling interest or significant influence. Publicly held equity securities are measured using quoted prices in their respective active markets with changes recorded through other expense on the statements of operations. Net gain on the strategic investments recognized in other expense in the Consolidated Statements of Operations for the year ended December 31, 2019 was $1.0 million and net loss on strategic investments recognized for the year ended December 31, 2018 was $1.8 million. As of December 31, 2019 and 2018, the aggregate carrying amount of the Company’s strategic equity investment was $2.3 million and $1.3 million, respectively, included in other assets on the Consolidated Balance Sheets. In August 2018, the Company entered into a license agreement with Neuren and obtained exclusive North American rights to develop and commercialize trofinetide for Rett syndrome and other indications. Under the terms of the agreement, Neuren received an upfront payment of $10.0 million and is eligible to receive milestone payments of up to $455.0 million, based on the achievement of certain development and annual net sales milestones. In addition, Neuren is eligible to receive tiered, escalating, double-digit percentage royalties based on net sales. The license agreement was accounted for as an asset acquisition and the upfront cash payment of $10.0 million was recorded in research and development expenses in the Consolidated Statements of Operations in the third quarter of 2018, as there is no alternative use for the asset. Corporate Credit Card Program In connection with the Company’s credit card program, the Company established a letter of credit in 2016 for $2.0 million, which has automatic annual extensions and is fully secured by restricted cash. Fleet Program In connection with the Company’s fleet program, the Company established a letter of credit for $0.4 million, which has automatic annual extensions and is fully secured by restricted cash. Legal Proceedings Between July 19 and August 3, 2018, following negative publicity about NUPLAZID, three purported company stockholders filed putative securities class action complaints (captioned Staublein v. ACADIA Pharmaceuticals, Inc., Case No. 18-cv-01647, Stone v. ACADIA Pharmaceuticals Inc., Case No. 18-cv-01672, and Barglow v. ACADIA Pharmaceuticals Inc., Case No. 18-cv-01812) in the U.S. District Court for the Southern District of California against the Company and certain of its current and former executive officers. Thereafter, several putative lead plaintiffs filed motions to consolidate the cases and to appoint a lead plaintiff. On January 3, 2019, the Court consolidated the cases under the caption In re ACADIA Pharmaceuticals Inc. Securities Litigation, Case No. 18-cv-01647, and took the lead plaintiff motions under submission. On February 26, 2019, the Court appointed a lead plaintiff and lead counsel. Lead plaintiff filed a consolidated complaint on April 15, 2019. The consolidated complaint generally alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by making materially false and misleading statements regarding the Company’s business, operations, and prospects by failing to disclose that adverse events and safety concerns regarding NUPLAZID threatened initial and continuing FDA approval, and by failing to disclose that the Company engaged in business practices likely to attract regulatory scrutiny. The consolidated complaint seeks unspecified monetary damages and other relief. Defendants filed a motion to dismiss the consolidated complaint on June 7, 2019 and the lead plaintiff filed an opposition on July 23, 2019. Defendants filed a reply on August 22, 2019. On November 12, 2019, the Court determined that the motion to dismiss was suitable for resolution without oral argument and took the motion hearing off calendar. On February 7, 2020, a purported company stockholder filed a derivative complaint (captioned Barney v. Davis et al., Case No. 20-cv-0238) in the U.S. District Court for the Southern District of California against the Company’s directors and certain of its current and former executive officers. The complaint asserts claims for breach of fiduciary duty, waste of corporate assets, and unjust enrichment arising from allegations similar to those in the federal securities class action described above. On February 19, 2020, the Court granted the parties’ stipulation to stay the derivative action pending a ruling on the motion to dismiss in the federal securities class action. Given the unpredictability inherent in litigation, the Company cannot predict the outcome of these matters. The Company is unable to estimate possible losses or ranges of losses that may result from these matters, and therefore it has not accrued any amounts in connection with these matters other than attorneys’ fees incurred to date. Government Investigation In September 2018 the Company received a civil investigative demand (“CID”) from the Department of Justice (“DOJ”) requesting certain documents and information related to the Company’s sales and marketing of NUPLAZID. The Company is cooperating with the DOJ’s request. Responding to the CID will require considerable resources and no assurance can be given as to the timing or outcome of the DOJ’s investigation.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

9. Commitments and Contingencies

Royalty Payments

Pursuant to the terms of its 2006 license agreement with the Ipsen Group, the Company is required to make royalty payments of two percent of net sales of NUPLAZID.

License Agreements

In May 2018, the Company signed an Exclusivity Deed (the “Deed”) with Neuren Pharmaceuticals Limited (“Neuren”) that provided for exclusive negotiations for a period of three months from the date of the Deed. Under the terms of the Deed, the Company invested $3.1 million to subscribe for 1,330,000 shares of Neuren and paid $0.9 million for the exclusive right to negotiate a deal with Neuren, which was recorded in selling, general and administrative expenses in the Consolidated Statements of Operations in the second quarter of 2018. At December 31, 2019, the Company continues to hold the equity securities as a strategic investment in which the Company does not have a controlling interest or significant influence. Publicly held equity securities are measured using quoted prices in their respective active markets with changes recorded through other expense on the statements of operations. Net gain on the strategic investments recognized in other expense in the Consolidated Statements of Operations for the year ended December 31, 2019 was $1.0 million and net loss on strategic investments recognized for the year ended December 31, 2018 was $1.8 million. As of December 31, 2019 and 2018, the aggregate carrying amount of the Company’s strategic equity investment was $2.3 million and $1.3 million, respectively, included in other assets on the Consolidated Balance Sheets.

In August 2018, the Company entered into a license agreement with Neuren and obtained exclusive North American rights to develop and commercialize trofinetide for Rett syndrome and other indications. Under the terms of the agreement, Neuren received an upfront payment of $10.0 million and is eligible to receive milestone payments of up to $455.0 million, based on the achievement of certain development and annual net sales milestones. In addition, Neuren is eligible to receive tiered, escalating, double-digit percentage royalties based on net sales. The license agreement was accounted for as an asset acquisition and the upfront cash payment of $10.0 million was recorded in research and development expenses in the Consolidated Statements of Operations in the third quarter of 2018, as there is no alternative use for the asset.

Corporate Credit Card Program

In connection with the Company’s credit card program, the Company established a letter of credit in 2016 for $2.0 million, which has automatic annual extensions and is fully secured by restricted cash.

Fleet Program

In connection with the Company’s fleet program, the Company established a letter of credit for $0.4 million, which has automatic annual extensions and is fully secured by restricted cash.

Legal Proceedings

Between July 19 and August 3, 2018, following negative publicity about NUPLAZID, three purported company stockholders filed putative securities class action complaints (captioned Staublein v. ACADIA Pharmaceuticals, Inc., Case No. 18-cv-01647, Stone v. ACADIA Pharmaceuticals Inc., Case No. 18-cv-01672, and Barglow v. ACADIA Pharmaceuticals Inc., Case No. 18-cv-01812) in the U.S. District Court for the Southern District of California against the Company and certain of its current and former executive officers. Thereafter, several putative lead plaintiffs filed motions to consolidate the cases and to appoint a lead plaintiff. On January 3, 2019, the Court consolidated the cases under the caption In re ACADIA Pharmaceuticals Inc. Securities Litigation, Case No. 18-cv-01647, and took the lead plaintiff motions under submission. On February 26, 2019, the Court appointed a lead plaintiff and lead counsel. Lead plaintiff filed a consolidated complaint on April 15, 2019. The consolidated complaint generally alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by making materially false and misleading statements regarding the Company’s business, operations, and prospects by failing to disclose that adverse events and safety concerns regarding NUPLAZID threatened initial and continuing FDA approval, and by failing to disclose that the Company engaged in business practices likely to attract regulatory scrutiny. The consolidated complaint seeks unspecified monetary damages and other relief. Defendants filed a motion to dismiss the consolidated complaint on June 7, 2019 and the lead plaintiff filed an opposition on July 23, 2019. Defendants filed a reply on August 22, 2019. On November 12, 2019, the Court determined that the motion to dismiss was suitable for resolution without oral argument and took the motion hearing off calendar.

On February 7, 2020, a purported company stockholder filed a derivative complaint (captioned Barney v. Davis et al., Case No. 20-cv-0238) in the U.S. District Court for the Southern District of California against the Company’s directors and certain of its current and former executive officers. The complaint asserts claims for breach of fiduciary duty, waste of corporate assets, and unjust enrichment arising from allegations similar to those in the federal securities class action described above. On February 19, 2020, the Court granted the parties’ stipulation to stay the derivative action pending a ruling on the motion to dismiss in the federal securities class action.

Given the unpredictability inherent in litigation, the Company cannot predict the outcome of these matters. The Company is unable to estimate possible losses or ranges of losses that may result from these matters, and therefore it has not accrued any amounts in connection with these matters other than attorneys’ fees incurred to date.

Government Investigation

In September 2018 the Company received a civil investigative demand (“CID”) from the Department of Justice (“DOJ”) requesting certain documents and information related to the Company’s sales and marketing of NUPLAZID. The Company is cooperating with the DOJ’s request. Responding to the CID will require considerable resources and no assurance can be given as to the timing or outcome of the DOJ’s investigation.