Business Combination	3 Months Ended
Business Combination	Mar. 31, 2024
Business Combination and Asset Acquisition [Abstract]
Business Combination	3. Business Combination In connection with, and as contemplated by, the Merger Agreement, on November 1, 2022, in accordance with the terms of the Separation and Distribution Agreement, dated as of March 23, 2022, by and among APAC, Ligand and Legacy OmniAb (the “Separation Agreement”), Ligand transferred the Legacy OmniAb business to Legacy OmniAb and made a contribution to the capital of Legacy OmniAb of $1.8 million, after deducting certain transaction and other expenses reimbursable by Legacy OmniAb (the “Separation”). Following the Separation, Ligand distributed on a pro rata basis to its stockholders all of the shares of common stock, par value $0.001 per share, of Legacy OmniAb (“Legacy OmniAb Common Stock”) held by Ligand, such that each holder of shares of common stock, par value $0.001 per share, of Ligand (“Ligand Common Stock”) was entitled to receive one share of Legacy OmniAb Common Stock for each share of Ligand Common Stock held by such holder as of the record date for the distribution, October 26, 2022 (the “Distribution”). Following the Separation and Distribution, on November 1, 2022, Merger Sub merged with and into Legacy OmniAb, with Legacy OmniAb surviving as a direct, wholly owned subsidiary of OmniAb. At the Closing Date, each outstanding share of Legacy OmniAb Common Stock was cancelled in exchange for 4.90007 shares of common stock of OmniAb, par value $0.0001 per share (“OmniAb Common Stock”) and 0.75842 shares of OmniAb Common Stock subject to certain price-based earnout triggers (the “Earnout Shares”). Holders of shares of Legacy OmniAb Common Stock received an aggregate 82,611,789 shares of the OmniAb Common Stock, excluding Earnout Shares, as consideration in the Business Combination. In addition, all outstanding Legacy OmniAb equity awards were converted into OmniAb equity awards to purchase, in the case of options, or receive, in the case of restricted stock units and performance-vesting restricted stock units, shares of OmniAb Common Stock, in each case, equal to the number of shares underlying such Legacy OmniAb equity awards multiplied by 4.90007. Each holder of an outstanding Legacy OmniAb equity award also received Earnout Shares equal to the number of shares of Legacy OmniAb Common Stock underlying such equity award multiplied by 0.75842. Holders of shares of Legacy OmniAb Common Stock and holders of Legacy OmniAb equity awards received an aggregate 14,999,243 Earnout Shares as consideration in the Business Combination. Fifty percent of the Earnout Shares will vest on the date on which the volume-weighted average price (“VWAP”) equals or exceeds $12.50 on any 20 trading days in any 30 consecutive trading-day period, and all remaining Earnout Shares will vest on the date on which the VWAP equals or exceeds $15.00 on any 20 trading days in any 30 consecutive trading-day period, in each case provided such vesting occurs during the five year period following the Closing Date (the “Earnout Period”); provided, that in the event of a Change of Control (as defined in the Merger Agreement) during the Earnout Period pursuant to which OmniAb or any of its stockholders have the right to receive, directly or indirectly, cash, securities or other property attributing a value of at least $12.50 (with respect to 50% of the Earnout Shares) or $15.00 (with respect to all Earnout Shares) per share of OmniAb Common Stock, and such Change of Control has been approved by a majority of the independent directors of the OmniAb board of directors, then such Earnout Shares shall be deemed to have vested immediately prior to such Change of Control. The Earnout Shares are accounted for as equity-classified equity instruments and recorded in additional paid-in capital as part of the Business Combination. Pursuant to the Sponsor Insider Letter Agreement executed concurrently with the Merger Agreement, by and among APAC, Avista Acquisition LP II (the “Sponsor”), Legacy OmniAb and certain insiders of APAC, 1,293,299 shares of OmniAb Common Stock held by the Sponsor became subject to the same price-based vesting conditions as the Earnout Shares (the “Sponsor Earnout Shares”). The Sponsor Earnout Shares are accounted for as equity-classified equity instruments and recorded in additional paid-in capital as part of the Business Combination. On the Closing Date, the Company completed the issuance and sale of 1,500,000 shares of the OmniAb Common Stock and 1,666,667 Forward Purchase Warrants to the Sponsor for an aggregate purchase price of $15.0 million (the “Forward Purchase”), pursuant to the amended and restated forward purchase agreement (the “A&R FPA”). Additionally, and also pursuant to the A&R FPA, on the Closing Date, the Company completed the sale of 8,672,934 shares of the OmniAb Common Stock and 1,445,489 Backstop Warrants to the Sponsor for a purchase price of $10.00 per share and aggregate purchase price of $86.7 million in order to backstop shareholder redemptions which would have otherwise resulted in the cash proceeds available to OmniAb following the Business Combination from OmniAb’s trust account to be less than $100,000,000. Refer to Note 9 – Stockholders' Equity, for additional information on the accounting for the Forward Purchase Warrants and Backstop Warrants.