Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Second Amended and Restated License Agreement with Vifor Pharma On February 18, 2022, the Company and Vifor Pharma entered into a Second Amended and Restated License Agreement, or the Vifor Second Amended Agreement, which amends and restates the Vifor First Amended Agreement. Pursuant to the Vifor Second Amended Agreement, the Company granted Vifor Pharma an exclusive license to sell vadadustat to the Supply Group in the United States, or the Territory. Vadadustat is the Company's investigational oral HIF prolyl hydroxylase inhibitor for the treatment of anemia due to CKD, for which the Company has filed a new drug application with the FDA. Like the Vifor First Amended Agreement, the Vifor Second Amended Agreement is structured as a profit share arrangement between the Company and Vifor Pharma in which the Company will receive approximately 66% of the profit, net of certain pre-specified costs. Under the Vifor Second Amended Agreement, Vifor Pharma will make an upfront payment to the Company of $25 million in lieu of the previously disclosed milestone payment of $25 million that Vifor Pharma was to pay to the Company following approval of vadadustat by the FDA. In addition, Vifor Pharma made an equity investment in the Company as further described below under “Investment Agreement.” The Company currently retains rights to commercialize vadadustat for use in the non-dialysis dependent CKD market and to sell to dialysis organizations outside of the Supply Group. As under the Vifor First Amended Agreement, during the term of the Vifor Second Amended Agreement, Vifor Pharma is not permitted to sell any HIF product that competes with vadadustat in the Territory to the Supply Group. As under the Vifor First Amended Agreement, the Vifor Second Amended Agreement provides that the Company and Vifor Pharma will enter into a commercial supply agreement for vadadustat pursuant to which the Company will supply all of Vifor Pharma’s requirements for vadadustat in the Territory. Under the Vifor Second Amended Agreement, Vifor Pharma will contribute $40 million to the Working Capital Fund, established to partially fund the Company's costs of purchasing vadadustat from its contract manufacturers, which amount of funding will fluctuate, and which funding the Company will repay to Vifor Pharma over time. Unless earlier terminated, the Vifor Second Amended Agreement will expire upon the later of the expiration of all patents that claim or cover vadadustat or the expiration of marketing or regulatory exclusivity for vadadustat in the Territory. Vifor Pharma may terminate the Vifor Second Amended Agreement in its entirety upon 30 months’ prior written notice after the first anniversary of the receipt of regulatory approval, if approved, from the FDA for vadadustat for dialysis-dependent CKD patients. The Company may terminate the Vifor Second Amended Agreement in its entirety for convenience, following the earlier of a certain period of time elapsing or following certain specified regulatory events, and upon six months’ prior written notice. If the Company so terminates for convenience, subject to a specified exception, the Company will pay a termination fee to Vifor Pharma. In addition, either party may, subject to a cure period, terminate the Vifor Second Amended Agreement in the event of the other party’s uncured material breach or bankruptcy. The Company may also terminate the Vifor Second Amended Agreement upon the occurrence of certain other events. The Vifor Second Amended Agreement also continues to include a standstill provision and customary representations and warranties. Investment Agreement In connection with entering into the Vifor Second Amended Agreement, on February 18, 2022, the Company and Vifor Pharma entered into an investment agreement, or the Second Investment Agreement, pursuant to which Akebia sold an aggregate of 4,000,000 shares of its common stock, par value $0.00001 per share, or the Shares, to Vifor Pharma for a total of $20 million on February 22, 2022. Vifor Pharma has agreed to a lock-up restriction to not sell or otherwise dispose of the Shares for a period of time following the effective date of the Investment Agreement as well as a customary standstill agreement. In addition, the Second Investment Agreement contains voting agreements made by Vifor Pharma with respect to the Shares. The Shares have not been registered pursuant to the Act and were issued and sold in reliance upon the exemption from registration contained in Section 4(a)(2) of the Act and/or Rule 506 promulgated thereunder, as the transaction does not involve any public offering within the meaning of Section 4(a)(2) of the Act. First Amendment and Waiver to Loan Agreement with Pharmakon On February 18, 2022, in connection with entering into the Vifor Second Amended Agreement, the Company and Pharmakon entered into the First Amendment and Waiver, or the First Amendment and Waiver, which amends and waives certain provisions of the Loan Agreement. Pursuant to the First Amendment and Waiver, the Collateral Agent and the Lenders agreed to (1) add the Working Capital Fund to the definition of Permitted Indebtedness under the Loan Agreement, as such term is defined in the Loan Agreement. subject to certain rights of notice and acceleration of the loans under the Loan Agreement granted to the Collateral Agent and Lenders in connection with the Company’s repayment of the Working Capital Fund to Vifor Pharma, and (2) provide the Company with a waiver with respect to a financial statement covenant included in the Loan Agreement and added a new covenant providing that our Quarterly Reports on Form 10-Q for the fiscal quarters ending June 30, 2022 and September 30, 2022 must not be subject to any qualification as to going concern. Amendment to Lease Agreement with CLPF One Marina Park Drive LLC On February 24, 2022, Keryx and the Company entered into an Assignment and Assumption Agreement, pursuant to which the Company assumed all of the rights and responsibilities of Keryx with respect to the One Marina Park Drive Office Lease, dated April 29, 2015, by and between Keryx and Fallon Cornerstone One MPD LLC, or Fallon, or the Boston Lease, for the entire twelfth floor of the building located at One Marina Park Drive, Boston, Massachusetts, or the Premises. On February 24, 2022, the Company entered into a First Amendment to Lease, or the First Lease Amendment, with CLPF One Marina Park Drive LLC (successor-in-interest to Fallon), or the Landlord, amending the Boston Lease for the Premises. Pursuant to the First Lease Amendment, the Company has agreed to extend the term of the Boston Lease, as amended, until July 31, 2031. The monthly lease payment for the Premises pursuant to the First Lease Amendment will be $200,122.00 commencing on August 1, 2023, with an annual rent escalation of approximately 2% commencing on August 1, 2024. The First Lease Amendment also includes a Landlord’s allowance for certain leasehold improvements to the Premises in an amount of up to $1,954,680.00, provided that such allowance must be used prior to August 1, 2024.