Revenue recognition - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2024	Sep. 29, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Oct. 01, 2023	Jul. 02, 2023	Apr. 02, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Net sales	$ 1,363,276	$ 1,354,652	$ 1,278,801	$ 1,308,636	$ 1,335,735	$ 1,381,130	$ 1,337,589	$ 1,386,972	$ 5,305,365	$ 5,441,426	$ 5,859,327
United States
Disaggregation of Revenue [Line Items]
Net sales									3,569,806	3,700,872	4,051,763
Europe
Disaggregation of Revenue [Line Items]
Net sales									955,520	885,386	924,301
Canada
Disaggregation of Revenue [Line Items]
Net sales									113,349	116,171	128,369
Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales									311,052	329,394	367,704
Other
Disaggregation of Revenue [Line Items]
Net sales									355,638	409,603	387,190
Operating segments \| Consumer Packaging
Disaggregation of Revenue [Line Items]
Net sales									2,531,852	2,471,048	2,564,004
Operating segments \| Industrial Paper Packaging
Disaggregation of Revenue [Line Items]
Net sales									2,349,488	2,374,113	2,684,563
Operating segments \| United States \| Consumer Packaging
Disaggregation of Revenue [Line Items]
Net sales									1,785,857	1,817,268	1,936,847
Operating segments \| United States \| Industrial Paper Packaging
Disaggregation of Revenue [Line Items]
Net sales									1,431,232	1,389,492	1,611,390
Operating segments \| Europe \| Consumer Packaging
Disaggregation of Revenue [Line Items]
Net sales									524,699	431,189	421,276
Operating segments \| Europe \| Industrial Paper Packaging
Disaggregation of Revenue [Line Items]
Net sales									371,896	389,261	434,076
Operating segments \| Canada \| Consumer Packaging
Disaggregation of Revenue [Line Items]
Net sales									17,486	16,076	18,372
Operating segments \| Canada \| Industrial Paper Packaging
Disaggregation of Revenue [Line Items]
Net sales									95,863	100,095	109,997
Operating segments \| Asia Pacific \| Consumer Packaging
Disaggregation of Revenue [Line Items]
Net sales									96,154	94,136	91,151
Operating segments \| Asia Pacific \| Industrial Paper Packaging
Disaggregation of Revenue [Line Items]
Net sales									213,127	233,446	275,395
Operating segments \| Other \| Consumer Packaging
Disaggregation of Revenue [Line Items]
Net sales									107,656	112,379	96,358
Operating segments \| Other \| Industrial Paper Packaging
Disaggregation of Revenue [Line Items]
Net sales									237,370	261,819	253,705
Total Reportable Segments
Disaggregation of Revenue [Line Items]
Net sales									424,025	596,265	610,760
Total Reportable Segments \| United States
Disaggregation of Revenue [Line Items]
Net sales									352,717	494,112	503,526
Total Reportable Segments \| Europe
Disaggregation of Revenue [Line Items]
Net sales									58,925	64,936	68,949
Total Reportable Segments \| Canada
Disaggregation of Revenue [Line Items]
Net sales									0	0	0
Total Reportable Segments \| Asia Pacific
Disaggregation of Revenue [Line Items]
Net sales									1,771	1,812	1,158
Total Reportable Segments \| Other
Disaggregation of Revenue [Line Items]
Net sales									$ 10,612	$ 35,405	$ 37,127