Guarantor Condensed Consolidating Financial Statements - Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net Sales	$ 1,599.1	$ 1,505.9
Cost of Sales	1,278.3	1,239.8
Selling, General and Administrative	135.5	124.5
Other Expense, Net	6.5	1.2
Business Combinations and Shutdown and Other Special Charges, Net	18.7	6.2
Income from Operations	160.1	134.2
Nonoperating Pension and Postretirement (Expense) Benefit Income	(151.6)	(0.1)
Interest Expense, Net	(33.7)	(35.0)
Loss on Modification or Extinguishment of Debt	0.0	0.0
(Loss) Income before Income Taxes and Equity Income of Unconsolidated Entity	(25.2)	99.1
Income Tax Benefit (Expense)	1.6	(4.0)
(Loss) Income before Equity Income of Unconsolidated Entity	(23.6)	95.1
Equity Income of Unconsolidated Entity	0.1	0.2
Equity in Net Earnings of Subsidiaries	0.0	0.0
Net (Loss) Income	(23.5)	95.3
Comprehensive Income (Loss)	111.8	101.4
Reportable Legal Entities | Issuer
Condensed Financial Statements, Captions [Line Items]
Net Sales	1,350.3	1,282.9
Cost of Sales	1,081.4	1,062.0
Selling, General and Administrative	111.5	101.1
Other Expense, Net	1.9	(2.9)
Business Combinations and Shutdown and Other Special Charges, Net	16.1	5.8
Income from Operations	139.4	116.9
Nonoperating Pension and Postretirement (Expense) Benefit Income	(152.0)	(0.6)
Interest Expense, Net	(32.8)	(33.6)
Loss on Modification or Extinguishment of Debt	0.0	0.0
(Loss) Income before Income Taxes and Equity Income of Unconsolidated Entity	(45.4)	82.7
Income Tax Benefit (Expense)	2.8	(3.4)
(Loss) Income before Equity Income of Unconsolidated Entity	(42.6)	79.3
Equity Income of Unconsolidated Entity	0.0	0.0
Equity in Net Earnings of Subsidiaries	19.1	16.0
Net (Loss) Income	(23.5)	95.3
Comprehensive Income (Loss)	111.8	101.4
Reportable Legal Entities | Combined Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Sales	0.0	0.0
Cost of Sales	(0.3)	(0.3)
Selling, General and Administrative	(0.7)	(0.7)
Other Expense, Net	0.0	0.0
Business Combinations and Shutdown and Other Special Charges, Net	0.0	0.0
Income from Operations	1.0	1.0
Nonoperating Pension and Postretirement (Expense) Benefit Income	0.0	0.0
Interest Expense, Net	0.0	0.0
Loss on Modification or Extinguishment of Debt	0.0	0.0
(Loss) Income before Income Taxes and Equity Income of Unconsolidated Entity	1.0	1.0
Income Tax Benefit (Expense)	(0.1)	0.0
(Loss) Income before Equity Income of Unconsolidated Entity	0.9	1.0
Equity Income of Unconsolidated Entity	0.0	0.0
Equity in Net Earnings of Subsidiaries	(0.9)	(1.0)
Net (Loss) Income	0.0	0.0
Comprehensive Income (Loss)	(5.1)	0.3
Reportable Legal Entities | Combined Nonguarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net Sales	379.3	340.6
Cost of Sales	327.7	295.7
Selling, General and Administrative	24.7	24.1
Other Expense, Net	4.6	4.1
Business Combinations and Shutdown and Other Special Charges, Net	2.6	0.4
Income from Operations	19.7	16.3
Nonoperating Pension and Postretirement (Expense) Benefit Income	0.4	0.5
Interest Expense, Net	(0.9)	(1.4)
Loss on Modification or Extinguishment of Debt	0.0	0.0
(Loss) Income before Income Taxes and Equity Income of Unconsolidated Entity	19.2	15.4
Income Tax Benefit (Expense)	(1.1)	(0.6)
(Loss) Income before Equity Income of Unconsolidated Entity	18.1	14.8
Equity Income of Unconsolidated Entity	0.1	0.2
Equity in Net Earnings of Subsidiaries	0.0	0.0
Net (Loss) Income	18.2	15.0
Comprehensive Income (Loss)	(99.1)	22.9
Consolidating Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Sales	(130.5)	(117.6)
Cost of Sales	(130.5)	(117.6)
Selling, General and Administrative	0.0	0.0
Other Expense, Net	0.0	0.0
Business Combinations and Shutdown and Other Special Charges, Net	0.0	0.0
Income from Operations	0.0	0.0
Nonoperating Pension and Postretirement (Expense) Benefit Income	0.0	0.0
Interest Expense, Net	0.0	0.0
Loss on Modification or Extinguishment of Debt	0.0	0.0
(Loss) Income before Income Taxes and Equity Income of Unconsolidated Entity	0.0	0.0
Income Tax Benefit (Expense)	0.0	0.0
(Loss) Income before Equity Income of Unconsolidated Entity	0.0	0.0
Equity Income of Unconsolidated Entity	0.0	0.0
Equity in Net Earnings of Subsidiaries	(18.2)	(15.0)
Net (Loss) Income	(18.2)	(15.0)
Comprehensive Income (Loss)	$ 104.2	$ (23.2)
Graphic Packaging International Partners (GPIP)
Condensed Financial Statements, Captions [Line Items]
Parent's ownership percentage	100.00%