| Document And Entity Information - USD ($) | Mar. 24, 2021 | Mar. 25, 2021 | Jun. 30, 2020 |
| Document Information [Line Items] | |||
| Entity, Registrant Name | ULTRALIFE CORPORATION | ||
| Current Fiscal Year End Date | --12-31 | ||
| Document, Fiscal Period Focus | FY | ||
| Document, Fiscal Year Focus | 2020 | ||
| Document, Type | 10-K/A | ||
| Document, Annual Report | true | ||
| Document, Period End Date | Dec. 31, 2020 | ||
| Document, Transition Report | false | ||
| Entity, File Number | 0-20852 | ||
| Entity, Incorporation, State or Country Code | DE | ||
| Entity, Tax Identification Number | 16-1387013 | ||
| Entity, Address, Address Line One | 2000 Technology Parkway | ||
| Entity, Address, City or Town | Newark | ||
| Entity, Address, State or Province | NY | ||
| Entity, Address, Postal Zip Code | 14513 | ||
| City Area Code | 315 | ||
| Local Phone Number | 332-7100 | ||
| Title of 12(b) Security | Common Stock, $0.10 par value per share | ||
| Trading Symbol | ULBI | ||
| 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 | Accelerated Filer | ||
| Entity, Small Business | true | ||
| Entity, Emerging Growth Company | false | ||
| Entity, Shell Company | false | ||
| Entity, Public Float | $ 68,675,435 | ||
| Entity, Common Stock Shares, Outstanding | 15,994,606 | ||
| Amendment Description | This Amendment No. 1 to the Annual Report on Form 10-K of Ultralife Corporation (the “Company”) for the year ended December 31, 2020 as originally filed with the Securities and Exchange Commission on February 4, 2021 (the “Original Form 10-K”) is being filed solely to include the information required by Items 10 through 14 of Part III and to amend Item 15 of Part IV and the Index of Exhibits of Form 10-K. This information from Part III of Form 10-K was previously omitted from the Original Form 10-K in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above referenced items to be incorporated in the Form 10-K by reference from our definitive proxy statement if such statement is filed no later than 120 days after our fiscal year-end. We are including this Part III information in this Amendment No. 1 to our Form 10-K because we will not file a definitive proxy statement containing such information within 120 days after the end of the fiscal year covered by the Original Form 10-K. We plan on filing our definitive proxy statement on or about May 31, 2021 as we are holding our 2021 Annual Stockholders’ Meeting (the “Meeting”) on July 21, 2021. In accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended (“Exchange Act”), Part III, Items 10 through 14, and Part IV, Item 15 of the Original Form 10-K are hereby amended and restated in their entirety. The reference on the cover of the Original Form 10-K to the incorporation by reference to portions of our definitive proxy statement into Part III of the Original Form 10-K is hereby deleted. Pursuant to Rule 12b-15 under the Exchange Act, this Amendment No. 1 contains new certifications pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, which are attached hereto. Except as set forth in the first paragraph of this Explanatory Note, this Amendment No. 1 does not amend, modify, or otherwise update any other information in and on exhibits filed with the Original Form 10-K. Accordingly, this Amendment No.1 should be read in conjunction with the Original Form 10-K. In addition, this Amendment No. 1 does not reflect events that may have occurred subsequent to the filing date of the Original Form 10-K. Unless expressly indicated or the context requires otherwise, the terms “the Company”, “we”, “our”, and “us” in this document refer to Ultralife Corporation (“Ultralife”), a Delaware corporation, and, where appropriate, its subsidiaries. | ||
| Amendment Flag | true | ||
| Entity, Central Index Key | 0000875657 |
