Basis of Presentation	9 Months Ended
	Oct. 03, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe 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 January 3, 2021, included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 18, 2021 (the 2020 consolidated financial statements). The Company’s third fiscal quarter ended on October 3, 2021 (2021) and September 27, 2020 (2020), each of which contained 13 weeks. The corresponding September year to date periods for 2021 and 2020 each contained 39 weeks.