Organization and Basis of Presentation	9 Months Ended
Organization and Basis of Presentation	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	ORGANIZATION AND BASIS OF PRESENTATION Ardelyx, Inc. (the “Company,” “we,” “us” or “our”) is a biopharmaceutical company focused on the discovery, development, and commercialization of innovative first-in-class medicines to improve treatment for people with kidney and cardiorenal diseases. We operate in one business segment, which is the research, development and commercialization of biopharmaceutical products. Basis of Presentation These condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and pursuant to the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules and regulations, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted. These condensed financial statements have been prepared on the same basis as our most recent annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary to present fairly our financial position, results of operations, changes in stockholders’ equity, and cash flows for the interim periods presented. The accompanying condensed financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of results to be expected for the entire year ending December 31, 2021, or for any other interim period or future year. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes thereto. On an ongoing basis, management evaluates its estimates, including those related to recognition of revenue, clinical trial accruals, contract manufacturing accruals, the fair value of assets and liabilities, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could materially differ from those estimates. Liquidity As of September 30, 2021, we had cash, cash equivalents and marketable securities of approximately $141.7 million. We believe our current available cash, cash equivalents and marketable securities will be sufficient to fund our planned expenditures and meet our obligations for at least 12 months following the filing of this Report on Form 10-Q. On July 28, 2021, we received a Complete Response Letter ("CRL") from the U.S. Food and Drug Administration ("FDA") regarding our New Drug Application ("NDA") for the control of serum phosphorus in adult patients with chronic kidney disease ("CKD") on dialysis in which the FDA noted additional requirements would need to be met in order to obtain approval for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. On July 29, 2021 we entered into a Fourth Amendment to our Term Loan Agreement which extended the period of time that we are permitted to make interest-only payments on the Term Loan to December 1, 2021, provided, however, the amendment provided that if the FDA did not approve our NDA for tenapanor for the control of serum phosphorus in adult patients with CKD on or before October 25, 2021, then the interest-only period would expire and principal repayments would be required to begin on November 1, 2021. Further, on July 29, 2021, our Board of Directors approved, and on August 2, 2021, we implemented a restructuring plan to better align our workforce and anticipated commercial and development spend with our capital resources and the needs of our business following the receipt of the CRL. On October 8, 2021, our Board of Directors approved, and on October 12, 2021 we began implementing, an additional restructuring plan to further reduce operating costs and better align our workforce with the needs of our business following the subsequent conclusion of an End of Review Type A Meeting ("End of Review Meeting") with the FDA on October 1, 2021. The restructuring plan is expected to be completed in December 2021. During November 2021, in compliance with the terms of our Loan Agreement as discussed in Note 5, we paid the first principal repayment on the Term Loan in the amount of $16.7 million. For additional information see Note 13, Subsequent Events. Failure to raise sufficient capital when needed or generate product revenue will further impact our ability to pursue our business strategies and could require us to further delay, scale back or discontinue one or more of our product development programs, commercialization efforts, or other aspects of our business plans. Summary of Significant Accounting Policies There have been no changes to the significant accounting policies disclosed in our most recent Annual Report on Form 10-K other than the following: Restructuring We recognize restructuring charges related to reorganization plans that have been committed to by management and when liabilities have been incurred. In connection with these activities, we record restructuring charges at fair value for, a) contractual employee termination benefits when obligations are associated to services already rendered, rights to such benefits have vested, and payment of benefits is probable and can be reasonably estimated, b) one-time employee termination benefits when management has committed to a plan of termination, the plan identifies the employees and their expected termination dates, the details of termination benefits are complete, it is unlikely changes to the plan will be made or the plan will be withdrawn and communication to such employees has occurred, and c) contract termination costs when a contract is terminated before the end of its term. One-time employee termination benefits are recognized in their entirety when communication has occurred and future services are not required. If future services are required, the costs are recorded ratably over the remaining period of service. Contract termination costs to be incurred over the remaining contract term without economic benefit are recorded in their entirety when the contract is canceled. The recognition of restructuring charges requires us to make certain judgments and estimates regarding the nature, timing and amount of costs associated with the planned reorganization plan. To the extent our actual results differ from our estimates and assumptions, we may be required to revise the estimates of future accrued restructuring liabilities, requiring the recognition of additional restructuring charges or the reduction of accrued restructuring liabilities already recognized. Such changes to previously estimated amounts may be material to the consolidated financial statements. Changes in the estimates of the restructuring charges are recorded in the period the change is determined. At the end of each reporting period, we evaluate the remaining accrued restructuring balances to ensure that no excess accruals are retained, and the utilization of the provisions are for their intended purpose in accordance with developed restructuring plans. Recent Accounting Pronouncements New Accounting Pronouncements - Recently Adopted We have adopted no new accounting pronouncements other than those disclosed in our most recent Annual Report on Form 10-K. Recent Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, an amendment which modifies the measurement and recognition of credit losses for most financial assets and certain other instruments. The amendment updates the guidance for measuring and recording credit losses on financial assets measured at amortized cost by replacing the “incurred loss” model with an “expected loss” model. Accordingly, these financial assets will be presented at the net amount expected to be collected. The amendment also requires that credit losses related to available-for-sale debt securities be recorded as an allowance through net income rather than reducing the carrying amount under the current, other-than-temporary-impairment model. For smaller reporting companies the guidance is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. On June 30, 2021, our public float exceeded $700 million and therefore, on December 31, 2021, we will no longer qualify as a “smaller reporting company” and will instead be considered a large accelerated filer. We expect to adopt Topic 326 in the fourth quarter of 2021. We do not expect the adoption of ASU 2016-13 to have a material impact on our financial statements and related disclosures.