Description of Business and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Description of Business	Description of Business Qualys, Inc. (the “Company”, "we", "us", "our") was incorporated in the state of Delaware on December 30, 1999. The Company is headquartered in Foster City, California and has wholly-owned subsidiaries throughout the world. The Company is a leading provider of cloud-based information technology ("IT"), security and compliance solutions that enable organizations to identify security risks to their IT infrastructures, help protect their IT systems and applications from ever-evolving cyber-attacks and achieve compliance with internal policies and external regulations. The Company’s cloud solutions address the growing security and compliance complexities and risks that are amplified by the dissolving boundaries between internal and external IT infrastructures and web environments, the rapid adoption of cloud computing and the proliferation of geographically dispersed IT assets. Organizations can use the Company’s integrated suite of solutions delivered on its Qualys Cloud Platform to cost-effectively obtain a unified view of their security and compliance posture across globally-distributed IT infrastructures.
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements and condensed footnotes have been prepared in accordance with accounting principles generally accepted in the United States ("U.S. GAAP") for interim financial information as well as the instructions to Form 10-Q and the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). Certain information and disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. The condensed consolidated balance sheet as of December 31, 2022, included herein, was derived from the audited financial statements as of that date but does not include all disclosures, including notes required by U.S. GAAP. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the financial position, results of operations and cash flows for the interim periods. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results of operations expected for the entire year ending December 31, 2023 or for any other future annual or interim periods. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC on February 23, 2023. Certain prior year amounts have been reclassified to conform to current year presentation.
Risk and Uncertainties	Risks and Uncertainties The uncertainty surrounding macroeconomic factors in the U.S. and globally characterized by the supply chain environment, inflationary pressure, rising interest rates, financial institution failures and associated uncertainty, labor shortages, significant volatility of global markets, reduced spending and extended sales cycles, and geopolitical conflicts could have a material adverse effect on the Company's long-term business and could lead to further economic disruption and expose the Company to greater risk as its current and potential customers may reduce or eliminate their overall spending on IT security.
Use of Estimates	Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of assets and liabilities at the date of the condensed consolidated financial statements and the reported results of operations during the reporting period. The Company’s management regularly assesses these estimates, which primarily affect revenue recognition, allowance for credit loss, the valuation of goodwill and intangible assets, leases, stock-based compensation and income tax provision. Actual results could differ from those estimates and such differences may be material to the accompanying unaudited condensed consolidated financial statements.
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements None. Recently Issued Accounting Pronouncements Not Yet Adopted The Company does not believe any new accounting pronouncements issued by the FASB that have not become effective will have a material impact on its condensed consolidated financial statements. There have been no material changes to the Company’s significant accounting policies set forth in "Note 1" of Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.