Revenue - Summary of Revenues Disaggregated by Product Line (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation Of Revenue [Line Items]
Revenue	$ 2,141.0	$ 1,979.5
Packaging
Disaggregation Of Revenue [Line Items]
Revenue	1,970.3	1,798.3
Paper
Disaggregation Of Revenue [Line Items]
Revenue	154.2	163.8
Corporate and Other
Disaggregation Of Revenue [Line Items]
Revenue	$ 16.5	$ 17.4	[1]

[1] The Corporate and Other segment sales to external customers is presented net of total company intersegment eliminations.