Investment in PersolKelly Pte Ltd.	9 Months Ended
Investment in PersolKelly Pte Ltd.	Sep. 27, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investment in PersolKelly Pte Ltd.	Investment in PersolKelly Pte. Ltd. The Company has a 49% ownership interest in the JV (see Investment in Persol Holdings footnote above), a staffing solutions business operating in eight geographies in the Asia-Pacific region. The operating results of the Company’s interest in the JV are accounted for on a one-quarter lag under the equity method and are reported in equity in net earnings (loss) of affiliate in the consolidated statements of earnings, which amounted to a gain of $1.8 million and a loss of $1.0 million in the third quarter and September year to date 2020, respectively, and a loss of $0.9 million and $1.0 million in the third quarter and September year to date 2019, respectively. This investment is evaluated for indicators of impairment on a periodic basis or whenever events or circumstances indicate the carrying amount may be other-than-temporarily impaired. If we conclude that there is an other-than-temporary impairment of this equity investment, we will adjust the carrying amount of the investment to the current fair value. The investment in equity affiliate on the Company’s consolidated balance sheet totaled $115.6 million as of third quarter-end 2020 and $117.2 million as of year-end 2019. The net amount due from the JV, a related party, was $10.9 million as of the third quarter-end 2020 and as of year-end 2019. The Company made loans, proportionate to its 49% ownership, to the JV for $7.0 million in 2018 and an additional $4.4 million in 2019 to fund working capital requirements as a result of their sustained revenue growth. The loans, which are outstanding as of third quarter-end 2020, are included in the net amounts due from the JV. Subsequent to the third quarter of 2020, the JV repaid $5.6 million of the outstanding loan balance; therefore, as of the third quarter-end 2020, $5.6 million of the loan balance is included in prepaid expenses and other current assets, and the remaining balance is included in other assets in the consolidated balance sheet. The carrying value of the loans approximates the fair value based on market interest rates. Accrued interest receivable, which is included in prepaid expenses and other current assets in the consolidated balance sheet, was not material at third quarter-end 2020 and year-end 2019. The JV is a supplier to certain MSP programs in the region and the amounts for services provided to the Company, which are included in trade accounts payable in the consolidated balance sheet, are not material. Expected credit losses are estimated over the contractual term of the loans. The required allowance is based on current and projected financial information from the JV, market-specific information and other relevant data available to the Company, as applicable. The allowance was not material at the third quarter-end 2020. The Company has accrued interest receivable from our loan to the JV. If applicable, we write off the uncollectible accrued interest receivable balance related to our loan to the JV within the same quarter the interest is determined to be uncollectible, which is considered timely. As such, an allowance for credit losses is not deemed necessary. Any write offs, if necessary, are recorded by reversing interest income. On April 1, 2020, 100% of the shares of Kelly Services Australia Pty Ltd and Kelly Services (New Zealand) Limited, both subsidiaries of the JV, were sold to an affiliate of Persol Holdings. The JV received proceeds of $17.5 million upon the sale and the Company received a direct royalty payment of $0.7 million.