Interim Financial Results (Footnotes) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Business Acquisition [Line Items]
Net (gains) losses on sales and impairments of businesses									$ 465.0	$ 205.0		$ 122.0
Asbestos litigation reserve adjustment			$ 43.0
Environmental remediation reserve adjustment		$ 7.0		$ 41.0	$ 10.0	$ 15.0
Gain (Loss) on Disposition of Business					1.0	(9.0)		$ (7.0)	0.0	0.0		(488.0)
Abandoned property removal			5.0	9.0	15.0	13.0	$ 11.0	11.0
Restructuring and other charges, net									195.0	57.0		29.0
Increase (Decrease) in Income Taxes Receivable					(6.0)
Printing Papers business spin-off costs	$ 9.0
Litigation reserves					19.0	22.0
Italian antitrust fine						32.0			0.0	32.0		0.0
Multi-employer pension plan exit liability						7.0		16.0
Other items	4.0	1.0	0.0	(3.0)	3.0		1.0
Non-operating pension (income) expense	(10.0)	(11.0)	(14.0)	(6.0)	(9.0)	(9.0)	(8.0)	(10.0)	(41.0)	36.0		494.0
Pre-tax charges (gains)	191.0	98.0	54.0	378.0	145.0	105.0	173.0	31.0
Luxembourg statutory tax rate change							9.0		7.0	0.0		(13.0)
State income tax legislative changes	(32.0)						(3.0)
Foreign tax audits							3.0
Internal investment restructuring					(53.0)
Foreign deferred tax valuation allowance					203.0				0.0	203.0		0.0
Tax impact of other special items	(18.0)	(26.0)	(18.0)	(12.0)	(28.0)	(14.0)	(5.0)	(6.0)
Non-operating pension expense (income), tax	(2.0)	(4.0)	(3.0)	(1.0)	(2.0)	(2.0)	(2.0)	(2.0)
Other Tax Expense (Benefit)	(48.0)	(22.0)	(15.0)	(11.0)	120.0	(16.0)	2.0	(8.0)
Graphic Packaging LLC [Member] | Reportable Subsegments [Member]
Business Acquisition [Line Items]
Gain on sale of portion of equity investment in Graphic Packaging				(33.0)
Global Cellulose Fibers
Business Acquisition [Line Items]
Global Cellulose Fibers goodwill impairment					52.0					52.0
Olmuksan [Member]
Business Acquisition [Line Items]
Net (gains) losses on sales and impairments of businesses	123.0
Brazil Industrial Packaging Total
Business Acquisition [Line Items]
Net (gains) losses on sales and impairments of businesses	0.0	(4.0)	8.0	344.0
Riverdale mill conversion
Business Acquisition [Line Items]
Restructuring and other charges, net				1.0	2.0	1.0	1.0	$ 1.0				3.0
Early debt extinguishment costs (see Note 13)
Business Acquisition [Line Items]
Restructuring and other charges, net	65.0	$ 105.0	18.0	8.0	21.0				196.0	21.0		10.0
EMEA packaging restructuring
Business Acquisition [Line Items]
Restructuring and other charges, net					17.0					15.0	[1]	$ 47.0	[2]
Overhead cost reduction initiative
Business Acquisition [Line Items]
Restructuring and other charges, net						21.0				21.0	[3]
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | APPM [Member]
Business Acquisition [Line Items]
Net (gains) losses on sales and impairments of businesses			$ (6.0)	$ 17.0	(1.0)	8.0	152.0			$ 159.0
India divestiture transaction costs					$ 3.0
Gain (loss) on sale of assets and impairment charge allocated to minority interest						$ (2.0)	$ (7.0)		$ (9.0)
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Olmuksan [Member]
Business Acquisition [Line Items]
Net (gains) losses on sales and impairments of businesses	$ 123.0

[1] Includes $14 million of severance and $1 million in other charges in conjunction with the restructuring of our EMEA Packaging business. The majority of the severance charges were paid in 2020.

[2] Includes $33 million of severance, $6 million in accelerated depreciation, $2 million in accelerated amortization and $6 million in other charges in conjunction with the optimization of our EMEA Packaging business. The majority of the severance charges recorded were paid throughout 2018.

[3] Includes pre-tax charges of $11 million, $6 million and $4 million in Corporate, the Printing Papers segment and the Global Cellulose Fibers segment, respectively, for severance related to an overhead cost reduction initiative. The majority of the severance charges were paid in 2020.