v3.26.1
Exit Activities - Schedule of Restructuring and Related Costs (Details) - Facility Closing - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Restructuring Cost and Reserve [Line Items]        
Total $ 4 $ 17 $ 77 $ 35
Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServicesSold        
Restructuring Cost and Reserve [Line Items]        
Accelerated Depreciation 0 4 0 8
Location, Statement of Income, Balance [Axis]: gpk:BusinessCombinationsBusinessExitShutdownAndOtherSpecialChargesNet        
Restructuring Cost and Reserve [Line Items]        
Asset Write-Offs and Start-Up Costs (1) 9 54 21
Severance Costs and Other $ 5 $ 4 $ 23 $ 6