Basis of Presentation (Policies)	6 Months Ended
Jun. 29, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited consolidated financial statements of Kelly Services, Inc. (the “Company,” “Kelly,” “we” or “us”) have been prepared in accordance with Rule 10-01 of Regulation S-X and do not include all the information and notes required by generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, all adjustments, including normal recurring adjustments, necessary for a fair statement of the results of the interim periods, have been made. The results of operations for such interim periods are not necessarily indicative of results of operations for a full year. The unaudited consolidated financial statements should be read in conjunction with the Company’s consolidated financial statements and notes thereto for the fiscal year ended December 29, 2024, included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 13, 2025 (the 2024 consolidated financial statements). There were no changes in accounting policies as disclosed in the Form 10-K. The Company’s second fiscal quarter ended on June 29, 2025 and June 30, 2024, each of which contained 13 weeks. The corresponding June year-to-date periods for 2025 and 2024 each contained 26 weeks.
Reclassifications	Certain reclassifications have been made to the prior year's consolidated financial statements to conform to the current year's presentation. Specifically, as discussed in the Revenue and Segment Disclosures footnotes, the Company made a change to its reportable segments during the first quarter of 2025.
New Accounting Pronouncements	Recently Issued Accounting Pronouncements Not Yet Adopted In November 2024, the FASB issued ASU 2024-03, Comprehensive income (Topic 220): Disaggregation of Income Statement Expenses. This ASU requires additional information about certain expense categories in the notes to financial statements. The new guidance will be effective for annual periods beginning after December 15, 2026, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which includes amendments to enhance income tax disclosures primarily through changes to the rate reconciliation and income taxes paid information. This ASU is effective for annual reporting periods beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements and related disclosures. In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC's Disclosure Update and Simplification Initiative, which modifies several disclosure and presentation requirements in the FASB accounting standard codification to align them with the SEC regulations. The effective date for each amendment will be the date on which the SEC's removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption permitted, by June 30, 2027. For any amendments in which the SEC has not yet removed the applicable requirement from their regulations by June 30, 2027, the pending content of the related amendment in the FASB codification will not be effective. The Company does not expect this update to have a material impact to its consolidated financial statements. Management has evaluated other recently issued accounting pronouncements and does not believe that any of these pronouncements will have a significant impact on the Company's consolidated financial statements and related disclosures.

Basis of Presentation (Policies)

6 Months Ended

Jun. 29, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The accompanying unaudited consolidated financial statements of Kelly Services, Inc. (the “Company,” “Kelly,” “we” or “us”) have been prepared in accordance with Rule 10-01 of Regulation S-X and do not include all the information and notes required by generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, all adjustments, including normal recurring adjustments, necessary for a fair statement of the results of the interim periods, have been made. The results of operations for such interim periods are not necessarily indicative of results of operations for a full year. The unaudited consolidated financial statements should be read in conjunction with the Company’s consolidated financial statements and notes thereto for the fiscal year ended December 29, 2024, included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 13, 2025 (the 2024 consolidated financial statements). There were no changes in accounting policies as disclosed in the Form 10-K. The Company’s second fiscal quarter ended on June 29, 2025 and June 30, 2024, each of which contained 13 weeks. The corresponding June year-to-date periods for 2025 and 2024 each contained 26 weeks.

Reclassifications

Certain reclassifications have been made to the prior year's consolidated financial statements to conform to the current year's presentation. Specifically, as discussed in the Revenue and Segment Disclosures footnotes, the Company made a change to its reportable segments during the first quarter of 2025.

New Accounting Pronouncements

Recently Issued Accounting Pronouncements Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Comprehensive income (Topic 220): Disaggregation of Income Statement Expenses. This ASU requires additional information about certain expense categories in the notes to financial statements. The new guidance will be effective for annual periods beginning after December 15, 2026, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements and related disclosures.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which includes amendments to enhance income tax disclosures primarily through changes to the rate reconciliation and income taxes paid information. This ASU is effective for annual reporting periods beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on its consolidated financial statements and related disclosures.

In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC's Disclosure Update and Simplification Initiative, which modifies several disclosure and presentation requirements in the FASB accounting standard codification to align them with the SEC regulations. The effective date for each amendment will be the date on which the SEC's removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption permitted, by June 30, 2027. For any amendments in which the SEC has not yet removed the applicable requirement from their regulations by June 30, 2027, the pending content of the related amendment in the FASB codification will not be effective. The Company does not expect this update to have a material impact to its consolidated financial statements.

Management has evaluated other recently issued accounting pronouncements and does not believe that any of these pronouncements will have a significant impact on the Company's consolidated financial statements and related disclosures.