Description of Business and Basis of Presentation	9 Months Ended
Sep. 30, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Organization NantKwest, Inc. (the Company) was incorporated in Illinois on October 7, 2002 under the name ZelleRx Corporation. On January 22, 2010, the Company changed its name to Conkwest, Inc., and on July 10, 2015, the Company changed its name to NantKwest, Inc. The Company is a biotechnology company headquartered in San Diego, California with certain operations in Culver City, California. The Company is commercially developing targeted direct-acting immunotherapeutic agents for a variety of clinical conditions. The Company holds the exclusive right to commercialize activated natural killer (aNK) cells, a commercially viable natural killer cell-line, and a variety of genetically modified derivatives capable of killing cancer and virally infected cells. The Company owns corresponding U.S. and foreign composition and methods-of-use patents and applications covering the clinical use of aNK cells as a therapeutic to treat a spectrum of clinical conditions. The Company also licensed exclusive commercial rights to a portfolio of CD16 bearing aNK cells along with the corresponding U.S. and foreign composition and methods-of-use patents and applications covering the non-clinical use in laboratory testing of monoclonal antibodies as well as clinical use as a therapeutic to treat cancers in combination with antibody products. The Company has licensed or sub-licensed its cell lines and intellectual property to numerous pharmaceutical and biotechnology companies for such non-clinical uses. The Company retains exclusive worldwide rights to clinical and research data, intellectual property and know-how developed with the Company’s aNK cells, as well as the only clinical grade master cell bank. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Inex Bio, Inc. (Note 3), and have been prepared in accordance with accounting principles generally accepted in the United States of America. All intercompany accounts and transactions have been eliminated in consolidation. Domicile Change In March 2014, the Company entered into a definitive merger and share exchange agreement pursuant to which the Company redomesticated from the State of Illinois to the State of Delaware and the Illinois Company ceased to exist (the Redomestication). In connection with the Redomestication, the holders of Class A and Class B common stock received one share of Class A and Class B common stock of the Delaware Company, respectively, in exchange for fifteen shares of the Illinois Company. The holders of Series B preferred stock received one share of Series B preferred stock of the Delaware Company in exchange for one share of the Illinois Company. The holders of any options, warrants or other securities are subject to adjustment based on the ratio of one for fifteen. All share numbers and per share prices in the accompanying financial statements have been adjusted to reflect the 1 for 15 exchange. Liquidity As of September 30, 2015, the Company had an accumulated deficit of approximately $172,723. The Company also had negative cash flow from operations of approximately $14,220 during the nine months ended September 30, 2015. The Company expects that it will likely need additional capital to further fund development of, and seek regulatory approvals for, its product candidates, and begin to commercialize any approved products. The Company is currently focused primarily on the development of immunotherapeutic treatments for cancers and debilitating viral infections using targeted cancer killing cell lines, and believes such activities will result in the Company’s continued incurrence of significant research and development and other expenses related to those programs. If the clinical trials for any of the Company’s product candidates fail or produce unsuccessful results and those product candidates do not gain regulatory approval, or if any of the Company’s product candidates, if approved, fails to achieve market acceptance, the Company may never become profitable. Even if the Company achieves profitability in the future, it may not be able to sustain profitability in subsequent periods. The Company intends to cover its future operating expenses through cash and cash equivalents on hand and through a combination of equity offerings, debt financings, government or other third-party funding, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements. Additional financing may not be available to the Company when needed and, if available, financing may not be obtained on terms favorable to the Company or its stockholders. While the Company expects its existing cash and cash equivalents will enable it to fund operations and capital expenditure requirements for at least the next twelve months, it may not have sufficient funds to reach commercialization. Failure to obtain adequate financing when needed may require the Company to delay, reduce, limit or terminate some or all of its development programs or future commercialization efforts or grant rights to develop and market product candidates that the Company might otherwise prefer to develop and market itself which could adversely affect the Company’s ability to operate as a going concern. If the Company raises additional funds from the issuance of equity securities, substantial dilution to existing stockholders may result. If the Company raises additional funds by incurring debt financing, the terms of the debt may involve significant cash payment obligations as well as covenants and specific financial ratios that may restrict the Company’s ability to operate its business. Forward Stock Split On July 10, 2015, the Company effected a 1.8515-for-1 forward stock split of its outstanding common stock. All applicable share data, per share amounts and related information in the financial statements and notes thereto have been adjusted retroactively to give effect to the 1.8515-for-1 forward stock split. Unaudited Interim Financial Information The accompanying unaudited financial statements and notes have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) as contained in the Financial Accounting Standards Board (the FASB) Accounting Standards Codification (the Codification or ASC) for interim financial information. In the opinion of management, the interim financial information includes all adjustments of a normal recurring nature necessary for a fair presentation of the results of operations, financial position and cash flows. The results of operations for the three and nine months ended September 30, 2015 are not necessarily indicative of the results for the full year or the results for any future periods. These financial statements should be read in conjunction with the audited financial statements and related notes for the year ended December 31, 2014 which are included in the Company’s final prospectus filed with the SEC on July 29, 2015 relating to the Company’s Registration Statement on Form S-1/A (File No. 333-205124) for the Company’s initial public offering.

1. Description of Business and Basis of Presentation

Organization

NantKwest, Inc. (the Company) was incorporated in Illinois on October 7, 2002 under the name ZelleRx Corporation. On January 22, 2010, the Company changed its name to Conkwest, Inc., and on July 10, 2015, the Company changed its name to NantKwest, Inc. The Company is a biotechnology company headquartered in San Diego, California with certain operations in Culver City, California. The Company is commercially developing targeted direct-acting immunotherapeutic agents for a variety of clinical conditions.

The Company holds the exclusive right to commercialize activated natural killer (aNK) cells, a commercially viable natural killer cell-line, and a variety of genetically modified derivatives capable of killing cancer and virally infected cells. The Company owns corresponding U.S. and foreign composition and methods-of-use patents and applications covering the clinical use of aNK cells as a therapeutic to treat a spectrum of clinical conditions.

The Company also licensed exclusive commercial rights to a portfolio of CD16 bearing aNK cells along with the corresponding U.S. and foreign composition and methods-of-use patents and applications covering the non-clinical use in laboratory testing of monoclonal antibodies as well as clinical use as a therapeutic to treat cancers in combination with antibody products. The Company has licensed or sub-licensed its cell lines and intellectual property to numerous pharmaceutical and biotechnology companies for such non-clinical uses.

The Company retains exclusive worldwide rights to clinical and research data, intellectual property and know-how developed with the Company’s aNK cells, as well as the only clinical grade master cell bank.

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Inex Bio, Inc. (Note 3), and have been prepared in accordance with accounting principles generally accepted in the United States of America. All intercompany accounts and transactions have been eliminated in consolidation.

Domicile Change

In March 2014, the Company entered into a definitive merger and share exchange agreement pursuant to which the Company redomesticated from the State of Illinois to the State of Delaware and the Illinois Company ceased to exist (the Redomestication). In connection with the Redomestication, the holders of Class A and Class B common stock received one share of Class A and Class B common stock of the Delaware Company, respectively, in exchange for fifteen shares of the Illinois Company. The holders of Series B preferred stock received one share of Series B preferred stock of the Delaware Company in exchange for one share of the Illinois Company. The holders of any options, warrants or other securities are subject to adjustment based on the ratio of one for fifteen. All share numbers and per share prices in the accompanying financial statements have been adjusted to reflect the 1 for 15 exchange.

Liquidity

As of September 30, 2015, the Company had an accumulated deficit of approximately $172,723. The Company also had negative cash flow from operations of approximately $14,220 during the nine months ended September 30, 2015. The Company expects that it will likely need additional capital to further fund development of, and seek regulatory approvals for, its product candidates, and begin to commercialize any approved products.

The Company is currently focused primarily on the development of immunotherapeutic treatments for cancers and debilitating viral infections using targeted cancer killing cell lines, and believes such activities will result in the Company’s continued incurrence of significant research and development and other expenses related to those programs. If the clinical trials for any of the Company’s product candidates fail or produce unsuccessful results and those product candidates do not gain regulatory approval, or if any of the Company’s product candidates, if approved, fails to achieve market acceptance, the Company may never become profitable. Even if the Company achieves profitability in the future, it may not be able to sustain profitability in subsequent periods. The Company intends to cover its future operating expenses through cash and cash equivalents on hand and through a combination of equity offerings, debt financings, government or other third-party funding, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements. Additional financing may not be available to the Company when needed and, if available, financing may not be obtained on terms favorable to the Company or its stockholders.

While the Company expects its existing cash and cash equivalents will enable it to fund operations and capital expenditure requirements for at least the next twelve months, it may not have sufficient funds to reach commercialization. Failure to obtain adequate financing when needed may require the Company to delay, reduce, limit or terminate some or all of its development programs or future commercialization efforts or grant rights to develop and market product candidates that the Company might otherwise prefer to develop and market itself which could adversely affect the Company’s ability to operate as a going concern. If the Company raises additional funds from the issuance of equity securities, substantial dilution to existing stockholders may result. If the Company raises additional funds by incurring debt financing, the terms of the debt may involve significant cash payment obligations as well as covenants and specific financial ratios that may restrict the Company’s ability to operate its business.

Forward Stock Split

On July 10, 2015, the Company effected a 1.8515-for-1 forward stock split of its outstanding common stock. All applicable share data, per share amounts and related information in the financial statements and notes thereto have been adjusted retroactively to give effect to the 1.8515-for-1 forward stock split.

Unaudited Interim Financial Information

The accompanying unaudited financial statements and notes have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) as contained in the Financial Accounting Standards Board (the FASB) Accounting Standards Codification (the Codification or ASC) for interim financial information. In the opinion of management, the interim financial information includes all adjustments of a normal recurring nature necessary for a fair presentation of the results of operations, financial position and cash flows. The results of operations for the three and nine months ended September 30, 2015 are not necessarily indicative of the results for the full year or the results for any future periods. These financial statements should be read in conjunction with the audited financial statements and related notes for the year ended December 31, 2014 which are included in the Company’s final prospectus filed with the SEC on July 29, 2015 relating to the Company’s Registration Statement on Form S-1/A (File No. 333-205124) for the Company’s initial public offering.