Organization and Description of the Business	12 Months Ended
Organization and Description of the Business	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Business	ORGANIZATION AND DESCRIPTION OF THE BUSINESS Seer, Inc. (the Company) was incorporated in Delaware on March 16, 2017, and is headquartered in Redwood City, California. In December 2020, the Company formed the wholly-owned subsidiary, Seer Securities Corporation, located in Massachusetts. The Company is a life sciences company focused on capturing deep molecular insights from the proteome to enable novel insights and breakthroughs in the understanding of biology and disease. Since inception, the Company has devoted its efforts principally to research, development and commercialization of its technology and products, recruiting management and technical staff, acquiring operating assets, and raising capital. The Company is subject to a number of risks, similar to other early-stage life science companies, including, but not limited to, development and commercialization of its products, market acceptance of its products, development by its competitors of new technological innovations, protection of its intellectual property, and raising additional capital. Initial Public Offering The Company’s registration statement on Form S-1 related to its initial public offering (IPO) was declared effective on December 3, 2020 by the Securities and Exchange Commission (SEC), and the Company’s Class A common stock began trading on the Nasdaq Global Select Market on December 4, 2020. On December 8, 2020, the Company completed its IPO, in which the Company sold 10,592,106 shares of Class A common stock, including 1,381,579 shares of Class A common stock that were offered and sold pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a price to the public of $19.00 per share. Including the option exercise, the Company received net proceeds of $183.9 million after deducting offering costs, underwriting discounts, and commissions of $17.4 million. Concurrent with the IPO, the Company issued 7,105,262 shares of its Class A common stock in a private placement for net proceeds of $130.3 million after deducting offering costs, underwriting discounts and commissions of $4.7 million. In addition, 526,315 shares of Class B common stock converted into Class A common stock in connection with the sale of such shares by an existing shareholder in a secondary transaction and 2,803,737 shares of Class B common stock were voluntarily converted to an equal amount of Class A common stock. Public Offering On February 1, 2021, the Company completed an underwritten public offering of 1,650,000 shares of its Class A common stock at a public offering price of $67.00 per share. The Company received net proceeds of $103.0 million after deducting offering costs, underwriting discounts, and commissions of $7.6 million. Liquidity As of December 31, 2021, the Company has incurred significant losses and has had negative cash flows from operations. As of December 31, 2021, the Company had cash, cash equivalents and investments of $493.3 million and an accumulated deficit of $126.5 million. Management expects to continue to incur significant expenses for the foreseeable future and to incur operating losses in the near term while the Company makes investments to support its anticipated growth. The Company believes that its cash and cash equivalents balance as of December 31, 2021 provides sufficient capital resources to continue its operations for at least 12 months from the issuance date of the accompanying consolidated financial statements.