| Cover page - USD ($) | 12 Months Ended | | |
| Dec. 31, 2021 | Mar. 07, 2022 | Jun. 30, 2021 |
| Cover [Abstract] | | | |
| Document Type | 10-K/A | | |
| Document Annual Report | true | | |
| Document Period End Date | Dec. 31,
2021 | | |
| Current Fiscal Year End Date | --12-31 | | |
| Document Transition Report | false | | |
| Entity File Number | 001-36570 | | |
| Entity Registrant Name | ZOSANO PHARMA CORPORATION | | |
| Entity Incorporation, State or Country Code | DE | | |
| Entity Tax Identification Number | 45-4488360 | | |
| Entity Address, Address Line One | 34790 Ardentech Court | | |
| Entity Address, City or Town | Fremont | | |
| Entity Address, State or Province | CA | | |
| Entity Address, Postal Zip Code | 94555 | | |
| City Area Code | 510 | | |
| Local Phone Number | 745-1200 | | |
| Title of 12(b) Security | Common stock, par value $0.0001 per share | | |
| Trading Symbol | ZSAN | | |
| Security Exchange Name | NASDAQ | | |
| Entity Well-known Seasoned Issuer | No | | |
| Entity Voluntary Filers | No | | |
| Entity Current Reporting Status | Yes | | |
| Entity Interactive Data Current | Yes | | |
| Entity Filer Category | Non-accelerated Filer | | |
| Entity Small Business | true | | |
| Entity Emerging Growth Company | false | | |
| Entity Shell Company | false | | |
| Auditor Attestation Flag | false | | |
| Entity Public Float | | | $ 104,972,443 |
| Entity Common Stock, Shares Outstanding | | 4,902,260 | |
| Documents Incorporated by Reference | DOCUMENTS INCORPORATED BY REFERENCE None. EXPLANATORY NOTE This Amendment No. 1 to Form 10-K (the "Amendment") amends the Annual Report on Form 10-K for the fiscal year ended December 31, 2021 originally filed on March 17, 2022 (the "Original Filing") by Zosano Pharma Corporation. We are filing this Amendment to present the information required by Items 10, 11, 12, 13 and 14 of Part III of Form 10-K because a definitive proxy statement containing such information will not be filed within 120 days after the end of our fiscal year covered by the Original Filing. This Amendment is being filed solely to: • amend and restate in its entirety Items 10, 11, 12, 13 and 14 of Part III to include the information required by such Items; • delete the reference on the cover of the Original Filing to the incorporation by reference of portions of our proxy statement into Part III of the Original Filing; • amend and restate in its entirety the Exhibit Index in Item 15 of Part IV of the Original Filing; and • file new certifications ("Certifications") of our principal executive officer and principal financial officer as exhibits to this Amendment under Item 15 of Part IV, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 and Rule 12b-15 under the Securities Exchange Act of 1934, as amended. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the Certifications have been omitted. We are not including the certifications under Section 906 of the Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment. Except as expressly set forth herein, this Amendment does not reflect events occurring after the date of the Original Filing or modify or update disclosure in, or exhibits to, the Original Filing. Furthermore, this Amendment does not change any previously reported financial results. Information not affected by the Amendment remains unchanged and reflects the disclosures made at the time the Original Filing was made. Accordingly, this Amendment should be read in conjunction with the Original Filing and our other filings with the Securities and Exchange Commission. References in this Amendment to the terms “Zosano”, the “Company”, “we”, “our” and “us” refer to Zosano Pharma Corporation. | | |
| Amendment Flag | false | | |
| Document Fiscal Year Focus | 2021 | | |
| Document Fiscal Period Focus | FY | | |
| Entity Central Index Key | 0001587221 | | |
