Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS On July 28, 2021, we received a CRL from the FDA regarding our NDA for the control of serum phosphorus in adult patients with CKD on dialysis. According to the CRL, while the FDA agrees “that the submitted data provide substantial evidence that tenapanor is effective in reducing serum phosphorus in CKD patients on dialysis,” the FDA characterizes the magnitude of the treatment effect as “small and of unclear clinical significance.” Additionally, the FDA noted that for the application to be approved, we will need “to conduct an additional adequate and well-controlled trial demonstrating a clinically relevant treatment effect on serum phosphorus or an effect on the clinical outcome thought to be caused by hyperphosphatemia in CKD patients on dialysis.” There were no safety, clinical pharmacology/biopharmaceutics, chemistry, manufacturing, and controls or non-clinical issues identified in the CRL. We intend to request a Type A meeting as soon as possible to discuss the CRL and determine potential paths forward for the approval of 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 the Loan Agreement (the “Amendment”) which extended the period of time that we are permitted to make interest-only payments on the Term Loan to December 1, 2021; provided that if we have not received FDA approval for our NDA for tenapanor for the control of serum phosphorus in adult patients with CDK on dialysis on or before October 25, 2021, the interest-only period will expire and principal repayments shall be required to begin on November 1, 2021. If principal repayments are required to begin prior to December 1, 2021 under the 2021 Amendments, then the first such repayment shall include all payments that would have been due if monthly principal repayment had begun on June 1, 2021. On July 29, 2021, our Board of Directors approved, and on August 2, 2021 we began implementing, 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. The restructuring plan is expected to be completed in August 2021. Under the restructuring plan, we are reducing our workforce by approximately 83 employees (approximately 33%). Impacted employees will receive cash payments equal to their base pay for a notice period of sixty (60) days and Company funded COBRA premiums through such notice period. In addition, impacted employees are eligible to receive severance benefits and additional Company funded COBRA premiums, contingent upon an impacted employee’s execution (and non-revocation) of a separation agreement, which includes a general release of claims against the Company. We expect that the workforce reduction will decrease our annual cash compensation costs by approximately $17 million. In connection with the restructuring, we estimate that we will incur restructuring charges of approximately $3.4 million, which will be recorded primarily in the third quarter of 2021, related to one-time termination notice and severance payments and other employee-related costs. The cash payments related to the reduction in workforce will be paid primarily during the third quarter of 2021. We may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the reduction in workforce. On July 30, 2021, a putative securities class action lawsuit was commenced in the U.S. District Court for the Northern District of California naming as defendants Ardelyx and two current officers. The complaint alleges that the defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 thereunder, by making false and misleading statements and omissions of material fact related to tenapanor. The plaintiff seeks to represent all persons who purchased or otherwise acquired Ardelyx securities between August 6, 2020, and July 19, 2021. The plaintiff seeks damages and interest, and an award of costs, including attorneys’ fees. We believe the plaintiff’s claims are without merit and we have not recorded any accrual for a contingent liability associated with these legal proceedings.