Revenue - Summary of Revenues Disaggregated by Product Line (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation Of Revenue [Line Items]
Revenue	$ 1,952.1	$ 2,237.3	$ 3,928.4	$ 4,373.7
Packaging
Disaggregation Of Revenue [Line Items]
Revenue	1,790.3	2,066.9	3,598.9	4,031.3
Paper
Disaggregation Of Revenue [Line Items]
Revenue	142.8	149.8	293.7	303.3
Corporate and Other
Disaggregation Of Revenue [Line Items]
Revenue	$ 19.0	$ 20.6	$ 35.8	$ 39.1