v3.26.1
Segment Information - Schedule of Total Segment Income From Operations Reconciled to Income (Loss) before Income Taxes (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]        
Income from Operations $ 95 $ 193 $ 114 $ 414
Nonoperating Pension and Postretirement Benefit Expense (1) (1) (1) (1)
Interest Expense, Net (68) (53) (132) (104)
Income (Loss) before Income Taxes 26 139 (19) 309
Operating Segments        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]        
Income from Operations 117 216 245 484
Operating Segments | Americas Paperboard Packaging        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]        
Income from Operations 110 187 240 415
Operating Segments | International Paperboard Packaging        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]        
Income from Operations 7 29 5 69
Corporate and Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Geographical Area, Revenue and Long-Lived Asset [Line Items]        
Income from Operations $ (22) $ (23) $ (131) $ (70)