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Fair Value Measurements - Narrative (Details) € in Millions, $ in Millions |  | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Feb. 15, 2022 USD ($) | Jul. 02, 2023 USD ($) | Apr. 02, 2023 USD ($) | Jan. 01, 2023 USD ($) | Oct. 02, 2022 USD ($) | Apr. 03, 2022 USD ($) | Oct. 03, 2021 USD ($) | Jul. 04, 2021 USD ($) | Apr. 04, 2021 USD ($) | Dec. 31, 2023 USD ($) | Jan. 01, 2023 USD ($) | Jan. 02, 2022 USD ($) | Nov. 02, 2023 EUR (€) | Jul. 03, 2022 USD ($) | Mar. 07, 2022 USD ($) | Mar. 08, 2021 USD ($) | Jan. 03, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payment to settle indemnification liabilities |  | $ 0.4 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Unrealized loss on forward contract |  |  |  |  |  |  |  |  |  | $ 3.6 | $ 0.0 | $ 0.0 |  |  |  |  |
Payment for contingent consideration liability, financing activities |  |  |  |  |  |  |  |  |  | 2.5 | 3.3 | 1.6 |  |  |  |  |
Equity securities, FV-NI and without readily determinable fair value |  |  |  | $ 6.4 |  |  |  |  |  | 6.4 | 6.4 |  |  |  |  |  |
Proceeds from sale of equity securities, fv-ni |  |  |  |  |  |  |  |  |  | 0.0 | 196.9 | 0.0 |  |  |  |  |
Goodwill impairment charge |  |  |  | 10.3 | $ 30.7 |  |  |  |  | 0.0 | 41.0 | 0.0 |  |  |  |  |
Foreign Exchange Forward |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative, notional amount | € |  |  |  |  |  |  |  |  |  |  |  |  | € 90.0 |  |  |  |
Foreign currency forward contract, net |  |  |  |  |  |  |  |  |  | $ 3.6 |  |  |  |  |  |  |
PersolKelly Pte. Ltd. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity ownership, excluding consolidated entity and equity method investee, percentage |  |  |  |  |  |  |  |  |  | 2.50% |  |  |  |  |  |  |
PersolKelly Pte. Ltd. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity securities, FV-NI and without readily determinable fair value |  |  |  |  |  |  |  |  |  | $ 6.4 |  |  |  |  |  |  |
Business Talent Group, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of equity securities, fv-ni |  |  |  |  |  |  |  | $ 5.0 |  |  |  |  |  |  |  |  |
Brazil |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disposition, indemnification liabilities, expense |  |  |  |  |  |  |  |  |  | (0.3) |  |  |  |  |  |  |
Brazil | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disposition, indemnification liabilities |  |  |  |  |  |  |  |  |  | 8.8 |  |  |  |  |  |  |
Greenwood/Asher |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payment for contingent consideration liability, financing activities |  |  |  |  |  |  |  |  |  | $ 1.4 | 0.7 |  |  |  |  |  |
Expense related to earnout liability |  |  |  |  |  |  |  |  |  |  | 1.0 |  |  |  |  |  |
RocketPower |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, liability |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.6 |  |
Goodwill impairment charge |  |  |  |  |  |  |  |  |  |  | 41.0 |  |  |  |  |  |
Insight |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payment for contingent consideration liability |  |  |  |  |  |  | $ 1.8 |  |  |  |  |  |  |  |  |  |
Expense related to earnout liability |  |  |  |  |  |  |  |  |  |  |  | $ 0.1 |  |  |  |  |
PersolKelly Pte. Ltd. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity ownership, excluding consolidated entity and equity method investee, percentage |  |  |  |  |  |  |  |  |  | 2.50% |  |  |  |  |  |  |
Equity securities, FV-NI and without readily determinable fair value |  |  |  |  |  |  |  |  |  | $ 6.4 |  |  |  |  |  |  |
Persol Holdings Investment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sale of equity securities, fv-ni | $ 196.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Kenzie Academy Inc. |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity securities, FV-NI and without readily determinable fair value |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.4 |
Debt and equity securities, realized gain (loss) |  |  |  |  |  |  |  |  | $ (1.4) |  |  |  |  |  |  |  |
Other Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market funds |  |  |  | 6.5 |  |  |  |  |  | 8.0 | 6.5 |  |  |  |  |  |
Level 3 | Brazil |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disposition, indemnification liabilities |  |  |  | 3.4 |  |  |  |  |  | 3.0 | 3.4 |  |  |  |  |  |
Level 3 | Greenwood/Asher |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, liability |  |  |  | 3.3 |  |  |  |  |  | 0.0 | 3.3 |  |  |  |  |  |
Payment for contingent consideration liability |  |  | $ 3.3 |  |  | $ 2.3 |  |  |  |  |  |  |  |  |  |  |
Level 3 | RocketPower |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, liability |  |  |  |  | $ 0.0 |  |  |  |  | 0.0 |  |  |  | $ 0.6 |  |  |
Level 3 | Insight |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, liability |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.7
Level 3 | Accounts Payable and Accrued Liabilities | Brazil |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disposition, indemnification liabilities |  |  |  | 0.3 |  |  |  |  |  | 0.1 | 0.3 |  |  |  |  |  |
Level 3 | Accounts Payable and Accrued Liabilities | RocketPower |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, liability |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.5 |  |  |
Level 3 | Other Long Term Liabilities | Brazil |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Disposition, indemnification liabilities |  |  |  | $ 3.1 |  |  |  |  |  | $ 2.9 | $ 3.1 |  |  |  |  |  |
Level 3 | Other Long Term Liabilities | RocketPower |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, liability |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.1 |  |  |

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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. 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