Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial information of FormFactor, Inc. is unaudited and has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). However, such information reflects all adjustments, consisting only of normal recurring adjustments, which are, in the opinion of management, necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods. The condensed consolidated financial statements included herein should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2022 Annual Report on Form 10-K filed with the SEC on February 24, 2023. The results of operations for the interim periods presented are not necessarily indicative of the results to be expected for the full year. Fiscal Year We operate on a 52/53 week fiscal year, whereby the fiscal year ends on the last Saturday of December. Fiscal 2023 and 2022 contain 52 weeks and 53 weeks, respectively, and the nine months ended September 30, 2023 and September 24, 2022 each contained 39 weeks. Fiscal 2023 will end on December 30, 2023. Significant Accounting Policies Our significant accounting policies have not changed during the nine months ended September 30, 2023 from those disclosed in our Annual Report on Form 10-K for the year ended December 31, 2022, except for: Government Assistance In January 2023, we received $18.0 million in cash from a California Competes Grant (the “Grant”) awarded from the California Governor’s Office of Business and Economic Development. The Grant requires FormFactor to create and maintain full-time jobs and make significant infrastructure investments within California over a 5-year term. If we do not meet the requirements of the Grant, we will be required to repay all or a portion of the Grant. The Grant is included in our Condensed Consolidated Balance Sheets within Deferred grant and we have elected to recognize the Grant when earned as an offset to Cost of revenues and Operating expenses within our Condensed Consolidated Statements of Income. We have presented the proceeds from the Grant as cash provided by operating activities within our Condensed Consolidated Statements of Cash Flows as the Grant is to offset operations. New Accounting Pronouncements Reference Rate Reform In March 2020, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU provides temporary optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Interbank Offered Rate (“LIBOR“) or another reference rate expected to be discontinued. In December 2022, the FASB issued ASU 2022-06, “Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848,” extending the relief offered in Topic 848 from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the optional expedients in Topic 848. In May 2023, the Company entered into a rate replacement amendment to its credit facility loan agreement to replace LIBOR with the Secured Overnight Financing Rate (“SOFR”) and concurrently signed an amendment to modify the floating rate option on its interest rate swap to match that of the debt. The Company applied practical expedients provided in Topic 848 allowing the modified instrument to be accounted for and presented in the same manner as the instrument existing before the modification. These modifications had no significant impact on our financial statements. Refer to Note 7, Debt, for further information regarding the terms of the credit facility loan agreement and interest rate swap agreement. Reclassifications Certain immaterial reclassifications were made to the prior year financial statements to conform to the current year presentation.