Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated interim financial statements for Xencor, Inc. (the Company, Xencor, we or us) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The consolidated financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. The preparation of consolidated interim financial statements requires the use of management’s estimates and assumptions that affect reported amounts of assets and liabilities at the date of the consolidated interim financial statements and the reported revenues and expenditures during the reported periods. These interim financial results are not necessarily indicative of the results expected for the full fiscal year or for any subsequent interim period. The accompanying unaudited consolidated interim financial statements and related notes should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s 2023 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 29, 2024. Principles of Consolidation The accompanying consolidated financial statements include the accounts of Xencor, Inc. and Gale Therapeutics Inc. (Gale), a variable interest entity (VIE) in which we are the primary beneficiary. Since we own less than 100% of Gale, the Company records net loss attributable to non-controlling interests in its consolidated statements of loss equal to the percentage of the economic or ownership interests retained in Gale by the non-controlling party. In determining whether we are the primary beneficiary of a VIE, we apply a qualitative approach that determines whether we have (1) the power to direct the activities of the VIE that most significantly impact the entity's economic performance and (2) the obligation to absorb losses of, or the right to receive benefits from the VIE that could potentially be significant to the VIE. We continuously assess whether we are the primary beneficiary of Gale as changes to existing relationships or future transactions may result in us consolidating or deconsolidating Gale. Use of Estimates The preparation of consolidated interim financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, other comprehensive income (loss) and the related disclosures. On an ongoing basis, management evaluates its estimates, including estimates related to its accrued clinical trial and manufacturing development expenses, stock-based compensation expense, evaluation of intangible assets, investments, leases and other assets for evidence of impairment, fair value measurements, and contingencies. Significant estimates in these consolidated interim financial statements include estimates made for royalty revenue, accrued research and development expenses, stock-based compensation expenses, intangible assets, incremental borrowing rate for right-of-use asset and lease liability, estimated standalone selling price of performance obligations, estimated time for completing delivery of performance obligations under certain arrangements, the likelihood of recognizing variable consideration, the carrying value of equity instruments without a readily determinable fair value, and recoverability of deferred tax assets. Reclassifications Certain prior year amounts in the consolidated financial statements and the notes thereto have been reclassified to conform to the current period's presentation. These reclassifications did not affect the prior period's total assets, liabilities, stockholders' equity, net loss or cash flows. During the six months ended June 30, 2024, we adopted a change in presentation on our consolidated statements of loss to include loss from disposal of fixed assets in operating expenses. The prior period has been revised to reflect this change in the presentation. Intangible Assets The Company maintains definite-lived intangible assets related to certain capitalized costs of acquired licenses and third-party costs incurred in establishing and maintaining its intellectual property rights to its platform technologies and development candidates. These assets are amortized over their useful lives, which are estimated to be the remaining patent life or the contractual term of the license. The straight-line method is used to record amortization expense. The Company assesses its intangible assets for impairment if indicators are present or changes in circumstances suggest that impairment may exist. There was no impairment charge recorded for the three and six months ended June 30, 2024 and 2023. The Company capitalizes certain in-process intangible assets that are then abandoned when they are no longer pursued or used in current research activities. We abandoned $0.4 million and $0.8 million of in-process intangible assets for the three and six months ended June 30, 2024. We abandoned $0.3 million and $0.6 million of in-process intangible assets during the three and six months ended June 30, 2023. Marketable Debt and Equity Securities The Company has an investment policy that includes guidelines on acceptable investment securities, minimum credit quality, maturity parameters, and concentration and diversification. The investment policy limits the maturity of any individual security to a maximum of 36 months. The average maturity of securities in the portfolio as of June 30, 2024 is less than 12 months. The Company invests its excess cash primarily in marketable debt securities issued by investment grade institutions. The Company considers its marketable debt securities to be available-for-sale because it is not more likely than not that the Company will be required to sell the securities before recovery of the amortized cost. These assets are carried at fair value and any impairment losses and recoveries related to the underlying issuer’s credit standing are recognized within other income (expense), while non-credit related impairment losses and recoveries are recognized within accumulated other comprehensive income (loss). There were no impairment losses or recoveries recorded for the three and six months ended June 30, 2024 and 2023. Accrued interest on marketable debt securities is included in the marketable securities’ carrying value. Each reporting period, the Company reviews its portfolio of marketable debt securities, using both quantitative and qualitative factors, to determine if each security’s fair value has declined below its amortized cost basis. During the three and six months ended June 30, 2024, the Company recorded an unrealized loss of $0.5 million and $1.9 million in its portfolio of marketable debt securities. During the three and six months ended June 30, 2023, the Company recorded an unrealized gain of $1.8 million and $5.1 million. The unrealized loss is due to the changing interest rate environment and is not due to changes in the credit quality of the underlying securities. The unrealized gain (loss) is recorded in other comprehensive income (loss) for the three and six months ended June 30, 2024 and 2023. The Company receives equity securities in connection with certain licensing transactions with its partners. These investments in equity securities are carried at fair value with changes in fair value recognized each period and reported within other income (expense). For equity securities with a readily determinable fair value, the Company remeasures these equity investments at each reporting period until such time that the investment is sold or disposed. If the Company sells an investment, any realized gain or loss on the sale of the securities will be recognized within other income (expense) in the consolidated statements of loss in the period of sale. The Company also has investments in equity securities without a readily determinable fair value, where the Company elects the measurement alternative to record the investment at its initial cost minus impairment, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. There was an impairment charge of $20.4 million recorded for the six months ended June 30, 2024 in connection with equity securities without a readily determinable fair value. There was no impairment charge recorded for the three and six months ended June 30, 2023. Liability Related to the Sale of Future Revenues We treat the sale of future Monjuvi royalties as debt, amortized under the effective interest rate method over the estimated life of the Monjuvi Royalty Sale Agreement. See Note 11. The amortization of the liability related to the sale of future Monjuvi royalties is based on our current estimate of future royalty payments. Royalty revenue will be recognized as earned and the payments made will be a reduction of the liability when paid. Non-cash Interest Expense on the Liability Related to the Sale of Future Royalties The total expected royalty payments less the net proceeds received are recorded as non-cash interest expense over the life of the liability. Interest is imputed on the unamortized portion using the effective interest method and is recorded based on the timing of the payments received over the term of the Monjuvi Royalty Sale Agreement. The actual interest rate will be affected by the timing of the royalty payments and changes in the forecasted revenue. Deferred Income Related to the Sale of Future Revenues We treat the sale of future Ultomiris royalties as deferred income, amortized under the units-of-revenue method by computing a ratio of the proceeds received to the total expected payments over the term of the Ultomiris Royalty Sale Agreement. See Note 11. The amortization of the liability related to the sale of future royalties is based on our current estimate of future royalty payments. Royalty revenue will be recognized as earned and the payments made will be a reduction of the liability when paid. Recent Accounting Pronouncements There have been no material changes in recently issued or adopted accounting standards from those disclosed in the Company's 2023 Annual Report on Form 10-K. The Company has reviewed all recently issued accounting pronouncements and does not believe they will have a material impact on our results of operations, financial condition or cash flows. There have been no other material changes to the significant accounting policies previously disclosed in the Company’s 2023 Annual Report on Form 10-K.