Nature of Business and Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP"). These unaudited condensed consolidated financial statements include all adjustments, which include normal recurring adjustments, necessary for the fair presentation of the Company’s financial position. These unaudited interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2024, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates and changes in these estimates are recorded when known. The unaudited condensed consolidated financial statements include the accounts of the Company and our wholly owned subsidiary, Aptevo Research and Development LLC ("Aptevo R&D"). All intercompany balances and transactions have been eliminated. For all periods presented in the financial statements and accompanying footnotes, share and per share amounts have been retroactively adjusted to reflect the reverse stock splits (as discussed below).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires estimates and assumptions that affect the reported amounts of assets and liabilities, revenues and expenses, and related disclosures of contingent liabilities in the unaudited condensed financial statements and accompanying notes. Estimates are used for, but not limited to, clinical accruals, useful lives of equipment, commitments and contingencies, stock-based compensation, fair value of common warrants, and incremental borrowing rate ("IBR") used for our lease. Given the global economic and geopolitical climate, these estimates are becoming more challenging, and actual results could differ materially from those estimates.
Significant Accounting Policies	Significant Accounting Policies Our significant accounting policies were reported in our Annual Report on Form 10-K for the year ended December 31, 2024 that was filed with the Securities and Exchange Commission (the "SEC") on February 14, 2025. Our other significant accounting policies have not changed materially from the policies previously reported.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In November 2023, the Financial Accounting Standards Board (FASB) issued ASU No. 2023-07, Segment Reporting: Improvements to Reportable Segment Disclosures. This guidance requires disclosure of incremental segment information on an annual and interim basis. This amendment is effective and has been adopted for our interim periods in fiscal year ending December 31, 2025.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires estimates and assumptions that affect the reported amounts of assets and liabilities, revenues and expenses, and related disclosures of contingent liabilities in the unaudited condensed financial statements and accompanying notes. Estimates are used for, but not limited to, clinical accruals, useful lives of equipment, commitments and contingencies, stock-based compensation, fair value of common warrants, and incremental borrowing rate ("IBR") used for our lease. Given the global economic and geopolitical climate, these estimates are becoming more challenging, and actual results could differ materially from those estimates.

Recently Adopted Accounting Pronouncements

In November 2023, the Financial Accounting Standards Board (FASB) issued ASU No. 2023-07, Segment Reporting: Improvements to Reportable Segment Disclosures. This guidance requires disclosure of incremental segment information on an annual and interim basis. This amendment is effective and has been adopted for our interim periods in fiscal year ending December 31, 2025.