EQUITY METHOD INVESTMENTS GPI Transactions (Details) $ in Millions		3 Months Ended					9 Months Ended		12 Months Ended
		Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2018
EQUITY METHOD INVESTMENTS GPI Transactions (Details) [Line Items]
Proceeds from sales of equity method investments							$ 843	$ 500
Net (gains) losses on sales of equity method investments		$ 1			$ 2		$ 205	$ 35
Graphic Packaging LLC [Member] | Reportable Subsegments
EQUITY METHOD INVESTMENTS GPI Transactions (Details) [Line Items]
Proceeds from sales of equity method investments			$ 402	$ 397	$ 250	$ 250
Graphic Packaging LLC [Member] | Reportable Subsegments
EQUITY METHOD INVESTMENTS GPI Transactions (Details) [Line Items]
Equity method investments, aggregate units exchanged					17,399,414	15,150,784			79,911,591
Equity method investments, aggregate units exchanged and sold on open market			22,773,077	24,588,316
Net (gains) losses on sales of equity method investments			$ 64	$ 33	$ 0	$ 33
Gain (loss) on disposition of stock in subsidiary or equity method investee, net of tax			48	25	$ 0	$ 25
Gain related to tax receivable agreement	[1]		66	41
Gain related to tax receivable agreement, net of tax	[1]		$ 50	$ 31

[1] The TRA entitles the Company to 50% of the amount of any tax benefits projected to be realized by GPIP upon the Company's exchange of its units. This amount is recorded in other receivables and is expected to be received within the next 12 months.