Pension and Other Retiree Benefits - Net Periodic Benefit Expense (Parenthetical) (Details) - Pension Plan [Member] - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
United States
Defined Benefit Plan Disclosure [Line Items]
Settlement	[1]	$ 0.0	$ 0.0	$ 0.0	$ 0.0
International
Defined Benefit Plan Disclosure [Line Items]
Settlement	[1]	$ 4.4	$ 0.0	$ 4.4	$ 0.0

[1] Settlement of $4.4 million resulting from the wind-up of the ACCO Brands Canada Salaried and Hourly pension plans being completed in the second quarter of 2024.