Commitments and Contingencies	12 Months Ended
Dec. 31, 2020
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 2% of net sales of NUPLAZID. License and Merger Agreements The Company has entered into various collaboration, licensing and merger agreements which provide the Company with rights to certain know-how, technology and patent rights. The agreements generally include upfront license fees, development and commercial milestone payments upon achievement of certain clinical and commercial development and annual net sales milestones, as well as royalties calculated as a percentage of product revenues, with rates that vary by agreement. The Company incurred $72.7 million, $1.4 million and $10.0 million in upfront and license payments in the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, the Company may be required to make milestone payments up to $2.2 billion in the aggregate. 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, 2020, 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 loss on the strategic investments recognized in other expense in the consolidated statements of operations for the year ended December 31, 2020 was $1.0 million and net gain on strategic investments recognized for the year ended December 31, 2019 was $1.0 million. As of December 31, 2020 and 2019, the aggregate carrying amount of the Company’s strategic equity investment was $1.3 million and $2.3 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. In March 2020, the Company entered into a license agreement and research collaboration with Vanderbilt University and obtained exclusive worldwide rights to develop and commercialize novel drug candidates targeting positive allosteric modulators of the muscarinic M1 receptor (the M1 PAM program) with the potential to treat a range of central nervous system disorders. Under the terms of the agreement, the Company paid Vanderbilt University an upfront license fee of $10.0 million and may be required to pay up to $515.0 million in milestone payments based on the achievement of certain clinical and commercial development and annual net sales milestones. In addition, the Company may be required to pay Vanderbilt University tiered royalties based on net sales. Furthermore, the Company is required to spend a minimum annual amount in development and the pursuit of regulatory approval for the M1 PAM compounds over the first three years of the license agreement. Such amounts are not material to the Company. The license agreement was accounted for as an asset acquisition and the upfront cash payment of $10.0 million was expensed to research and development in the first quarter of 2020 as there is no future alternative use for the assets. In August 2020, the Company entered into the Merger Agreement with CerSci, with CerSci remaining as the surviving corporation and the Company’s wholly owned subsidiary. CerSci’s lead development program is a unique Reactive Species Decomposition Accelerant, a non-opioid, mechanism focused on interrupting pathways that sensitize neurons to pain. The portfolio contains additional preclinical stage programs, including brain penetrant compounds, with potential for symptomatic and disease modifying treatment utility in neurodegenerative diseases. The Company incurred an aggregate of $52.8 million in upfront consideration and transaction costs, of which, $44.3 million was paid through the issuance of approximately 1.2 million shares of the Company’s common stock. In addition, under the terms of the Merger Agreement, the Company may be required to pay CerSci’s former equity holders up to $887.0 million in cash upon the achievement of certain development, commercialization and sales milestones, in addition to tiered cash royalties in the mid-single digits based on annual net sales. As substantially all of the fair value of the gross assets acquired was concentrated in the in-process research and development intangible assets acquired, the Company concluded that this transaction did not meet the definition of a business combination pursuant to FASB Accounting Standard Codification Topic 805, Business Combinations. As such, the transaction was accounted for as an asset acquisition and the upfront consideration of $45.7 million was expensed to research and development in the third quarter of 2020 as there is no future alternative use for the assets. 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. On June 1, 2020, the Court granted the motion in part and gave lead plaintiff leave to file an amended complaint. On July 16, 2020, lead plaintiff filed the amended complaint. Defendants filed a motion to dismiss the amended complaint on August 28, 2020. Lead plaintiff opposed the motion on September 15, 2020. Defendants’ reply in support of the motion to dismiss was filed on November 11, 2020. The hearing on the motion was rescheduled for February 2021 and ultimately taken off calendar. Accordingly, the court will make a decision based on the parties’ pleadings. 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. On July 16, 2020, the parties filed a joint motion to continue to stay the derivative action until the defendants in the federal securities class action answer, or the federal securities class action is dismissed with prejudice and all appeals are exhausted, or any party to the stipulation to stay gives 15 days’ written notice that it no longer consents to the voluntary stay. The Court stayed the action on July 22, 2020. On September 9, 2020, the Court substituted plaintiffs and re-captioned the case Shumacher v. Davis et al., Case No. 20-cv-0238. On June 23, 2020, another derivative complaint (captioned Lazarus v. Davis et al., Case No. 20-cv-0843) was filed in the U.S. District Court for the District of Delaware. Like the previous derivative complaint, 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 September 9, 2020, the Court transferred the case to the U.S. District Court for the Southern District of California and re-captioned the case Lazarus v. Davis et al., Case No. 20-cv-1774. On July 24, 2020, the Company filed complaints against (i) Aurobindo Pharma Limited and its affiliate Aurobindo Pharma USA, Inc. and (ii) Teva Pharmaceuticals USA, Inc. and its affiliate Teva Pharmaceutical Industries Ltd., and on July 30, 2020, the Company filed complaints against (i) Hetero Labs Limited and its affiliates Hetero Labs Limited Unit-V and Hetero USA Inc., (ii) MSN Laboratories Private Ltd. and its affiliate MSN Pharmaceuticals, Inc., and (iii) Zydus Pharmaceuticals (USA) Inc. and its affiliate Cadila Healthcare Limited. These complaints, which were filed in the United States District Court for the District of Delaware, allege infringement of certain of the Company’s Orange Book-listed patents covering NUPLAZID. The cases have been assigned to the Honorable Richard G. Andrews. On September 1, 2020, Aurobindo filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On September 22, 2020, the Company filed its answer to Aurobindo’s counterclaims. On August 31, 2020, Teva filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On September 21, 2020, the Company filed its answer to Teva’s counterclaims. On October 5, 2020, Hetero filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On October 26, 2020, the Company filed its answer to Hetero’s counterclaims. On September 30, 2020, MSN filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity regarding certain of our Orange Book-listed patents covering NUPLAZID. On November 5, 2020, the Company filed its first amended complaint against MSN in the United States District Court for the District of Delaware, alleging infringement of certain of our Orange Book-listed patents covering NUPLAZID. On November 19, 2020, MSN filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity regarding certain of the Company’s Orange Book-listed patents covering NUPLAZID. On December 10, 2020, the Company filed its answer to MSN’s counterclaims. On November 2, 2020, Zydus filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On November 23, 2020, the Company filed its answer to Zydus’s counterclaims. On December 8, 2020, the parties’ joint proposed scheduling order was entered by Judge Andrews. A joint trial in the matters is scheduled for May 15, 2023. Management currently believes that none of the foregoing claims or actions pending against the Company as of September 30, 2020 is likely to have, individually or in the aggregate, a material adverse effect on the Company’s business, liquidity, financial position, or results of operations. Given the unpredictability inherent in litigation, however, 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 has cooperated with the DOJ’s request since that time. In October 2020, the DOJ advised the Company that it had concluded its investigation of the Company and would not be taking any further action related to the CID. As such, DOJ advised the Company that it does not need to respond further to the CID.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

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 2% of net sales of NUPLAZID.

License and Merger Agreements

The Company has entered into various collaboration, licensing and merger agreements which provide the Company with rights to certain know-how, technology and patent rights. The agreements generally include upfront license fees, development and commercial milestone payments upon achievement of certain clinical and commercial development and annual net sales milestones, as well as royalties calculated as a percentage of product revenues, with rates that vary by agreement. The Company incurred $72.7 million, $1.4 million and $10.0 million in upfront and license payments in the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, the Company may be required to make milestone payments up to $2.2 billion in the aggregate.

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, 2020, 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 loss on the strategic investments recognized in other expense in the consolidated statements of operations for the year ended December 31, 2020 was $1.0 million and net gain on strategic investments recognized for the year ended December 31, 2019 was $1.0 million. As of December 31, 2020 and 2019, the aggregate carrying amount of the Company’s strategic equity investment was $1.3 million and $2.3 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.

In March 2020, the Company entered into a license agreement and research collaboration with Vanderbilt University and obtained exclusive worldwide rights to develop and commercialize novel drug candidates targeting positive allosteric modulators of the muscarinic M1 receptor (the M1 PAM program) with the potential to treat a range of central nervous system disorders. Under the terms of the agreement, the Company paid Vanderbilt University an upfront license fee of $10.0 million and may be required to pay up to $515.0 million in milestone payments based on the achievement of certain clinical and commercial development and annual net sales milestones. In addition, the Company may be required to pay Vanderbilt University tiered royalties based on net sales. Furthermore, the Company is required to spend a minimum annual amount in development and the pursuit of regulatory approval for the M1 PAM compounds over the first three years of the license agreement. Such amounts are not material to the Company. The license agreement was accounted for as an asset acquisition and the upfront cash payment of $10.0 million was expensed to research and development in the first quarter of 2020 as there is no future alternative use for the assets.

In August 2020, the Company entered into the Merger Agreement with CerSci, with CerSci remaining as the surviving corporation and the Company’s wholly owned subsidiary. CerSci’s lead development program is a unique Reactive Species Decomposition Accelerant, a non-opioid, mechanism focused on interrupting pathways that sensitize neurons to pain. The portfolio contains additional preclinical stage programs, including brain penetrant compounds, with potential for symptomatic and disease modifying treatment utility in neurodegenerative diseases. The Company incurred an aggregate of $52.8 million in upfront consideration and transaction costs, of which, $44.3 million was paid through the issuance of approximately 1.2 million shares of the Company’s common stock. In addition, under the terms of the Merger Agreement, the Company may be required to pay CerSci’s former equity holders up to $887.0 million in cash upon the achievement of certain development, commercialization and sales milestones, in addition to tiered cash royalties in the mid-single digits based on annual net sales. As substantially all of the fair value of the gross assets acquired was concentrated in the in-process research and development intangible assets acquired, the Company concluded that this transaction did not meet the definition of a business combination pursuant to FASB Accounting Standard Codification Topic 805, Business Combinations. As such, the transaction was accounted for as an asset acquisition and the upfront consideration of $45.7 million was expensed to research and development in the third quarter of 2020 as there is no future alternative use for the assets.

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. On June 1, 2020, the Court granted the motion in part and gave lead plaintiff leave to file an amended complaint. On July 16, 2020, lead plaintiff filed the amended complaint. Defendants filed a motion to dismiss the amended complaint on August 28, 2020. Lead plaintiff opposed the motion on September 15, 2020. Defendants’ reply in support of the motion to dismiss was filed on November 11, 2020. The hearing on the motion was rescheduled for February 2021 and ultimately taken off calendar. Accordingly, the court will make a decision based on the parties’ pleadings.

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. On July 16, 2020, the parties filed a joint motion to continue to stay the derivative action until the defendants in the federal securities class action answer, or the federal securities class action is dismissed with prejudice and all appeals are exhausted, or any party to the stipulation to stay gives 15 days’ written notice that it no longer consents to the voluntary stay. The Court stayed the action on July 22, 2020. On September 9, 2020, the Court substituted plaintiffs and re-captioned the case Shumacher v. Davis et al., Case No. 20-cv-0238.

On June 23, 2020, another derivative complaint (captioned Lazarus v. Davis et al., Case No. 20-cv-0843) was filed in the U.S. District Court for the District of Delaware. Like the previous derivative complaint, 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 September 9, 2020, the Court transferred the case to the U.S. District Court for the Southern District of California and re-captioned the case Lazarus v. Davis et al., Case No. 20-cv-1774.

On July 24, 2020, the Company filed complaints against (i) Aurobindo Pharma Limited and its affiliate Aurobindo Pharma USA, Inc. and (ii) Teva Pharmaceuticals USA, Inc. and its affiliate Teva Pharmaceutical Industries Ltd., and on July 30, 2020, the Company filed complaints against (i) Hetero Labs Limited and its affiliates Hetero Labs Limited Unit-V and Hetero USA Inc., (ii) MSN Laboratories Private Ltd. and its affiliate MSN Pharmaceuticals, Inc., and (iii) Zydus Pharmaceuticals (USA) Inc. and its affiliate Cadila Healthcare Limited. These complaints, which were filed in the United States District Court for the District of Delaware, allege infringement of certain of the Company’s Orange Book-listed patents covering NUPLAZID. The cases have been assigned to the Honorable Richard G. Andrews. On September 1, 2020, Aurobindo filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On September 22, 2020, the Company filed its answer to Aurobindo’s counterclaims. On August 31, 2020, Teva filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On September 21, 2020, the Company filed its answer to Teva’s counterclaims. On October 5, 2020, Hetero filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On October 26, 2020, the Company filed its answer to Hetero’s counterclaims. On September 30, 2020, MSN filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity regarding certain of our Orange Book-listed patents covering NUPLAZID. On November 5, 2020, the Company filed its first amended complaint against MSN in the United States District Court for the District of Delaware, alleging infringement of certain of our Orange Book-listed patents covering NUPLAZID. On November 19, 2020, MSN filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity regarding certain of the Company’s Orange Book-listed patents covering NUPLAZID. On December 10, 2020, the Company filed its answer to MSN’s counterclaims. On November 2, 2020, Zydus filed its answer and counterclaims seeking declaratory judgments of noninfringement and invalidity. On November 23, 2020, the Company filed its answer to Zydus’s counterclaims. On December 8, 2020, the parties’ joint proposed scheduling order was entered by Judge Andrews. A joint trial in the matters is scheduled for May 15, 2023.

Management currently believes that none of the foregoing claims or actions pending against the Company as of September 30, 2020 is likely to have, individually or in the aggregate, a material adverse effect on the Company’s business, liquidity, financial position, or results of operations. Given the unpredictability inherent in litigation, however, 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 has cooperated with the DOJ’s request since that time. In October 2020, the DOJ advised the Company that it had concluded its investigation of the Company and would not be taking any further action related to the CID. As such, DOJ advised the Company that it does not need to respond further to the CID.