Subsequent Events	12 Months Ended
Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Co-Development Agreement for PB2452 with SFJ Pharmaceuticals In January 2020, the Company entered into the SFJ Agreement, pursuant to which SFJ will provide funding to the Company to support the global development of PB2452 as a reversal agent for the antiplatelet drug ticagrelor in patients with uncontrolled major or life-threatening bleeding or requiring urgent surgery or an invasive procedure. Under the SFJ Agreement, SFJ has agreed to pay the Company up to $120.0 million to support the clinical development of PB2452. In March 2020, SFJ paid the Company an initial $10.0 million. SFJ will pay the Company an additional $80.0 million through cost reimbursements followed by six equal quarterly payments beginning with the quarter ending September 30, 2020 through the quarter ending December 31, 2021, and up to an additional $30.0 million upon the achievement of specified clinical development milestones with respect to the Company's clinical development of PB2452. If the FDA approves a Biologics License Application for PB2452, the Company has agreed to pay to SFJ an initial payment of $5.0 million and an additional $325.0 million in the aggregate in seven additional annual payments (the “U.S. Approval Payments”). If the EMA or the national regulatory authorities in certain European countries provide marketing approval of PB2452, the Company will pay SFJ an initial payment of $5.0 million and an additional $205.0 million in the aggregate in seven additional annual payments (the “EU Approval Payments”). The majority of the U.S. Approval Payments and the EU Approval Payments will be made from the third anniversary to the seventh anniversary of marketing approval in the applicable jurisdiction. If either the Pharmaceuticals and Medical Devices Agency (the “PMDA”) of Japan or the National Medical Products Administration (the “NMPA”) of China provide marketing approval of PB2452, the Company will pay SFJ an initial payment of $1.0 million and then an additional $59.0 million in the aggregate in eight additional annual payments (the “Japan/China Approval Payments”), with the majority of the payments to be made from the fifth anniversary to the eighth anniversary of marketing approval. The Japan/China Approval Payments will only be paid once regardless of receipt of marketing approval in both Japan and China. The U.S. Approval Payments, EU Approval Payments and Japan/China Approval Payments will be proportionately adjusted in the event that the actual funding from SFJ is lower or greater than $120.0 million. The Company will not be obligated to make the U.S. Approval Payments if it does not receive marketing approval for PB2452 from the FDA, the EU Approval Payments if it does not receive marketing approval for PB2452 from the EMA or the national regulatory authority in certain European countries or the Japan/China Approval Payments if it does not receive marketing approval for PB2452 from either the PMDA or the NMPA. In connection with the SFJ Agreement, the Company issued to SFJ a ten-year warrant exercisable for 2,200,000 shares of the Company's common stock at an exercise price of $6.50 per share. The warrant is exercisable as follows: (i) 1,100,000 shares may be exercised at any time after the effective date of the SFJ Agreement, provided that SFJ may not sell such exercised shares until one year after such effective date, and (ii) the remaining 1,100,000 shares may be exercised at any time at SFJ’s election if the results of the Company’s Phase 3 trial meet the interim primary endpoint as set forth in the Phase 3 trial protocol. Under the SFJ Agreement, the Company granted SFJ a security interest in all of the Company's assets pertaining to PB2452. The SFJ Agreement also provides for certain default provisions and early payment provisions. Amendment to MedImmune License In January 2020, in connection with the Company entering the SFJ Agreement, the Company entered into an amendment to the MedImmune License pursuant to which MedImmune consented to a potential assignment of the MedImmune License and transfer of the Company’s business related to PB2452 to SFJ in the event of the occurrence of certain program transfer events, should they ever occur. Viamet Asset Purchase Agreement In January 2020, the Company entered into an asset purchase agreement (the "PB6440 Agreement") with Viamet Pharmaceuticals Holdings, LLC ("Viamet") and its wholly-owned subsidiary, Selenity Therapeutics (Bermuda), Ltd. ("Selenity" and, together with Viamet, the "Sellers"), pursuant to which the Company acquired all of the assets and intellectual property rights related to the Sellers' proprietary CYP11B2 inhibitor compound, formerly known as SE-6440 or VT-6440, and certain other CYP11B2 inhibitor compounds that are covered by the patent rights acquired by the Company under the PB6440 Agreement (together, "Compounds"). The Company intends to designate SE-6440 as PB6440, which the Company intends to develop for treatment-resistant hypertension. Under the terms of the PB6440 Agreement, the Company is required to pay Viamet an upfront fee of $100,000 upon the closing of the transaction, up to $5.1 million upon the achievement of certain development and intellectual property milestones, up to $142.5 million upon the achievement of certain commercial milestones and low- to mid-single digit royalty percentages on the net sales of approved products. Consent and Amendment to 2019 Loan In March 2020, in connection with the Company entering the SFJ Agreement, the Company entered into a Consent and First Amendment (the "First Amendment") to its 2019 Loan with SVB and WestRiver (together, the "Lenders"). Pursuant to the First Amendment, the Lenders consented to the Company's entry into the SFJ Agreement, which required that the Company obtain the consent of SVB to grant SFJ a security interest in all of the Company’s assets owned or controlled by the Company that are necessary for the manufacture, use or sale of PB2452. The First Amendment also provides that in the event that the SFJ Agreement were terminated or the Company breached or was in default of the SFJ Agreement (after giving effect to applicable grace periods), the Company will grant to the Lenders a security interest in an amount of unrestricted cash equal to at least the aggregate outstanding balance of all of the obligations under the 2019 Loan as security for the prompt payment of such obligations. In connection with the First Amendment, the Company and the Lenders concurrently entered into an intellectual property security agreement granting the Lenders a security interest in all of the Company’s intellectual property. In addition, the Company, SVB, in its capacity as administrative agent and collateral agent, the Lenders and SFJ entered into a subordination agreement pursuant to which SFJ’s liens and right to payment and performance under the SFJ Agreement are subordinated to the Lenders’ liens and right to payment in full under the 2019 Loan.

Subsequent Events

Co-Development Agreement for PB2452 with SFJ Pharmaceuticals

In January 2020, the Company entered into the SFJ Agreement, pursuant to which SFJ will provide funding to the Company to support the global development of PB2452 as a reversal agent for the antiplatelet drug ticagrelor in patients with uncontrolled major or life-threatening bleeding or requiring urgent surgery or an invasive procedure. Under the SFJ Agreement, SFJ has agreed to pay the Company up to $120.0 million to support the clinical development of PB2452. In March 2020, SFJ paid the Company an initial $10.0 million. SFJ will pay the Company an additional $80.0 million through cost reimbursements followed by six equal quarterly payments beginning with the quarter ending September 30, 2020 through the quarter ending December 31, 2021, and up to an additional $30.0 million upon the achievement of specified clinical development milestones with respect to the Company's clinical development of PB2452.

If the FDA approves a Biologics License Application for PB2452, the Company has agreed to pay to SFJ an initial payment of $5.0 million and an additional $325.0 million in the aggregate in seven additional annual payments (the “U.S. Approval Payments”). If the EMA or the national regulatory authorities in certain European countries provide marketing approval of PB2452, the Company will pay SFJ an initial payment of $5.0 million and an additional $205.0 million in the aggregate in seven additional annual payments (the “EU Approval Payments”). The majority of the U.S. Approval Payments and the EU Approval Payments will be made from the third anniversary to the seventh anniversary of marketing approval in the applicable jurisdiction. If either the Pharmaceuticals and Medical Devices Agency (the “PMDA”) of Japan or the National Medical Products Administration (the “NMPA”) of China provide marketing approval of PB2452, the Company will pay SFJ an initial payment of $1.0 million and then an additional $59.0 million in the aggregate in eight additional annual payments (the “Japan/China Approval Payments”), with the majority of the payments to be made from the fifth anniversary to the eighth anniversary of marketing approval. The Japan/China Approval Payments will only be paid once regardless of receipt of marketing approval in both Japan and China. The U.S. Approval Payments, EU Approval Payments and Japan/China Approval Payments will be proportionately adjusted in the event that the actual funding from SFJ is lower or greater than $120.0 million. The Company will not be obligated to make the U.S. Approval Payments if it does not receive marketing approval for PB2452 from the FDA, the EU Approval Payments if it does not receive marketing approval for PB2452 from the EMA or the national regulatory authority in certain European countries or the Japan/China Approval Payments if it does not receive marketing approval for PB2452 from either the PMDA or the NMPA.

In connection with the SFJ Agreement, the Company issued to SFJ a ten-year warrant exercisable for 2,200,000 shares of the Company's common stock at an exercise price of $6.50 per share. The warrant is exercisable as follows: (i) 1,100,000 shares may be exercised at any time after the effective date of the SFJ Agreement, provided that SFJ may not sell such exercised shares until one year after such effective date, and (ii) the remaining 1,100,000 shares may be exercised at any time at SFJ’s election if the results of the Company’s Phase 3 trial meet the interim primary endpoint as set forth in the Phase 3 trial protocol.

Under the SFJ Agreement, the Company granted SFJ a security interest in all of the Company's assets pertaining to PB2452. The SFJ Agreement also provides for certain default provisions and early payment provisions.

Amendment to MedImmune License

In January 2020, in connection with the Company entering the SFJ Agreement, the Company entered into an amendment to the MedImmune License pursuant to which MedImmune consented to a potential assignment of the MedImmune License and transfer of the Company’s business related to PB2452 to SFJ in the event of the occurrence of certain program transfer events, should they ever occur.

Viamet Asset Purchase Agreement

In January 2020, the Company entered into an asset purchase agreement (the "PB6440 Agreement") with Viamet Pharmaceuticals Holdings, LLC ("Viamet") and its wholly-owned subsidiary, Selenity Therapeutics (Bermuda), Ltd. ("Selenity" and, together with Viamet, the "Sellers"), pursuant to which the Company acquired all of the assets and intellectual property rights related to the Sellers' proprietary CYP11B2 inhibitor compound, formerly known as SE-6440 or VT-6440, and certain other CYP11B2 inhibitor compounds that are covered by the patent rights acquired by the Company under the PB6440 Agreement (together, "Compounds"). The Company intends to designate SE-6440 as PB6440, which the Company intends to develop for treatment-resistant hypertension. Under the terms of the PB6440 Agreement, the Company is required to pay Viamet an upfront fee of $100,000 upon the closing of the transaction, up to $5.1 million upon the achievement of certain development and intellectual property milestones, up to $142.5 million upon the achievement of certain commercial milestones and low- to mid-single digit royalty percentages on the net sales of approved products.

Consent and Amendment to 2019 Loan

In March 2020, in connection with the Company entering the SFJ Agreement, the Company entered into a Consent and First Amendment (the "First Amendment") to its 2019 Loan with SVB and WestRiver (together, the "Lenders"). Pursuant to the First Amendment, the Lenders consented to the Company's entry into the SFJ Agreement, which required that the Company obtain the consent of SVB to grant SFJ a security interest in all of the Company’s assets owned or controlled by the Company that are necessary for the manufacture, use or sale of PB2452. The First Amendment also provides that in the event that the SFJ Agreement were terminated or the Company breached or was in default of the SFJ Agreement (after giving effect to applicable grace periods), the Company will grant to the Lenders a security interest in an amount of unrestricted cash equal to at least the aggregate outstanding balance of all of the obligations under the 2019 Loan as security for the prompt payment of such obligations.

In connection with the First Amendment, the Company and the Lenders concurrently entered into an intellectual property security agreement granting the Lenders a security interest in all of the Company’s intellectual property. In addition, the Company, SVB, in its capacity as administrative agent and collateral agent, the Lenders and SFJ entered into a subordination agreement pursuant to which SFJ’s liens and right to payment and performance under the SFJ Agreement are subordinated to the Lenders’ liens and right to payment in full under the 2019 Loan.