Information on Business Segments - Operating (Loss) Income by Segment (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Segment operating (loss) income	[1]	$ (111.2)	$ 55.2	$ (105.3)	$ 65.3
Interest expense		13.8	15.5	27.1	29.4
Interest income		(2.2)	(2.2)	(4.1)	(4.6)
Non-operating pension expense		4.8	0.2	5.2	0.3
Other (income) expense, net		(0.2)	(0.3)	(0.8)	1.5
(Loss) income before income tax		(127.4)	42.0	(132.7)	38.7
Operating Segments
Segment Reporting Information [Line Items]
Segment operating (loss) income		(100.9)	67.5	(82.0)	89.5
Corporate
Segment Reporting Information [Line Items]
Segment operating (loss) income		(10.3)	(12.3)	(23.3)	(24.2)
ACCO Brands Americas | Operating Segments
Segment Reporting Information [Line Items]
Segment operating (loss) income		(108.7)	60.4	(102.6)	72.7
ACCO Brands International | Operating Segments
Segment Reporting Information [Line Items]
Segment operating (loss) income		$ 7.8	$ 7.1	$ 20.6	$ 16.8

[1] Operating (loss) income is defined as i) net sales; ii) less cost of products sold; iii) less selling, general and administrative expenses; iv) less amortization of intangibles; v) less restructuring; and vi) less change in the fair value of contingent consideration.