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Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Sep. 29, 2019	Jun. 30, 2019	Dec. 30, 2018
Persol Holdings Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost of equity securities	$ 19.2		$ 18.8
Business Talent Group, LLC
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities without readily determinable fair value, amount	5.0		$ 5.0
Kenzie Academy Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities without readily determinable fair value, with changes in fair value in net income	$ 1.3
Kenzie Academy Inc. \| Other Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities without readily determinable fair value, amount		$ 1.0