Basis of Presentation (Policies)	3 Months Ended
Mar. 29, 2026
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 28, 2025, included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 12, 2026 (the 2025 consolidated financial statements). There were no changes in accounting policies from those disclosed in the Form 10-K. The Company’s first fiscal quarter ended on March 29, 2026 and March 30, 2025, each of which contained 13 weeks.
Reclassifications	Certain reclassifications have been made to the prior year's consolidated financial statements to conform to the current year's presentation, as discussed in the Revenue and Segment Disclosures footnotes. All amounts are reported in millions except for share and per share data.
New Accounting Pronouncements	Recently Adopted In July 2025, the FASB issued ASU 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. This ASU allows for a practical expedient to be used when estimating expected credit losses on current accounts receivable and/or current contract assets arising from transactions under Topic 606. The new guidance was effective for annual periods beginning after December 15, 2025, with early adoption permitted. This ASU applies to trade accounts receivable and may have an impact on the calculation of the allowance for uncollectible accounts receivable. The Company adopted this guidance in the first quarter of 2026 and the adoption did not have a material impact to the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements Not Yet Adopted In December 2025, the FASB issued ASU 2025-11, Interim Reporting, which is intended to improve the navigability of the guidance in ASC 270, Interim Reporting, and clarify when it applies. The amendment specifies when an entity is subject to ASC 270, and addresses the form and content of financial statements and interim disclosure requirements. The ASU clarifies that an entity must disclose events since the end of the last annual reporting period that have a material impact. The ASU is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, and early adoption is permitted. The Company does not expect this update to have a material impact to the Company's consolidated financial statements. In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other - Internal-Use Software (Subtopic 350-40). This ASU simplifies and modernizes guidance for internal-use software by clarifying capitalization thresholds, improving comparability and reducing judgment diversity across all software development methodologies. This ASU is effective for annual reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on the Company’s consolidated financial statements and related disclosures. 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 the 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 the Company’s 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 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 its 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 the Company’s 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)

3 Months Ended

Mar. 29, 2026

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 28, 2025, included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 12, 2026 (the 2025 consolidated financial statements). There were no changes in accounting policies from those disclosed in the Form 10-K. The Company’s first fiscal quarter ended on March 29, 2026 and March 30, 2025, each of which contained 13 weeks.

Reclassifications

Certain reclassifications have been made to the prior year's consolidated financial statements to conform to the current year's presentation, as discussed in the Revenue and Segment Disclosures footnotes. All amounts are reported in millions except for share and per share data.

New Accounting Pronouncements

Recently Adopted

In July 2025, the FASB issued ASU 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. This ASU allows for a practical expedient to be used when estimating expected credit losses on current accounts receivable and/or current contract assets arising from transactions under Topic 606. The new guidance was effective for annual periods beginning after December 15, 2025, with early adoption permitted. This ASU applies to trade accounts receivable and may have an impact on the calculation of the allowance for uncollectible accounts receivable. The Company adopted this guidance in the first quarter of 2026 and the adoption did not have a material impact to the Company’s consolidated financial statements.

Recently Issued Accounting Pronouncements Not Yet Adopted

In December 2025, the FASB issued ASU 2025-11, Interim Reporting, which is intended to improve the navigability of the guidance in ASC 270, Interim Reporting, and clarify when it applies. The amendment specifies when an entity is subject to ASC 270, and addresses the form and content of financial statements and interim disclosure requirements. The ASU clarifies that an entity must disclose events since the end of the last annual reporting period that have a material impact. The ASU is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, and early adoption is permitted. The Company does not expect this update to have a material impact to the Company's consolidated financial statements.

In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other - Internal-Use Software (Subtopic 350-40). This ASU simplifies and modernizes guidance for internal-use software by clarifying capitalization thresholds, improving comparability and reducing judgment diversity across all software development methodologies. This ASU is effective for annual reporting periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact of the new guidance on the Company’s consolidated financial statements and related disclosures.

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 the 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 the Company’s 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 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 its 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 the Company’s 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.