Company and Nature of Business	12 Months Ended
Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company and Nature of Business	Note 1. Company and Nature of Business Personalis, Inc. (the “Company”) was incorporated in Delaware on February 21, 2011 and began operations in September 2011. The Company formed a wholly owned subsidiary, Personalis (UK) Ltd., in August 2013 and a wholly owned subsidiary, Shanghai Personalis Biotechnology Co., Ltd. (which is referred to as “Personalis (Shanghai) Ltd” herein), in October 2020. The Company is a growing cancer genomics company transforming the development of next-generation therapies by providing more comprehensive molecular data about each patient’s cancer and immune response. The Company provides sequencing and data analysis services to support the development of cancer therapies. The Company also provides sequencing and data analysis services to support population sequencing initiatives, which accounts for the majority of revenues. Cancer genomic services are sold primarily to pharmaceutical companies, biopharmaceutical companies, universities, non-profits, and government entities, while services for population sequencing initiatives are sold primarily to government entities. The principal markets for the Company’s services are the United States and Europe. In June 2020, the Company began partnering with a clinical genomics and life sciences company headquartered in China as a means to expand business operations into China. The Company operates and manages its business as one reportable operating segment, which is the sale of sequencing and data analysis services. The Company has incurred losses to date and expects to incur additional losses for the foreseeable future. The Company continues to invest the majority of its resources in the development and growth of its business, including investments in product development and sales and marketing efforts. The Company’s activities have been financed to date primarily through the sale of equity securities and cash from operations.

Company and Nature of Business

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Note 1. Company and Nature of Business

Personalis, Inc. (the “Company”) was incorporated in Delaware on February 21, 2011 and began operations in September 2011. The Company formed a wholly owned subsidiary, Personalis (UK) Ltd., in August 2013 and a wholly owned subsidiary, Shanghai Personalis Biotechnology Co., Ltd. (which is referred to as “Personalis (Shanghai) Ltd” herein), in October 2020. The Company is a growing cancer genomics company transforming the development of next-generation therapies by providing more comprehensive molecular data about each patient’s cancer and immune response. The Company provides sequencing and data analysis services to support the development of cancer therapies. The Company also provides sequencing and data analysis services to support population sequencing initiatives, which accounts for the majority of revenues. Cancer genomic services are sold primarily to pharmaceutical companies, biopharmaceutical companies, universities, non-profits, and government entities, while services for population sequencing initiatives are sold primarily to government entities. The principal markets for the Company’s services are the United States and Europe. In June 2020, the Company began partnering with a clinical genomics and life sciences company headquartered in China as a means to expand business operations into China. The Company operates and manages its business as one reportable operating segment, which is the sale of sequencing and data analysis services.

The Company has incurred losses to date and expects to incur additional losses for the foreseeable future. The Company continues to invest the majority of its resources in the development and growth of its business, including investments in product development and sales and marketing efforts. The Company’s activities have been financed to date primarily through the sale of equity securities and cash from operations.