EQUITY METHOD INVESTMENTS Narrative (Details) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2020	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2018	Dec. 31, 2020 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity earnings (loss), net of taxes	$ 94	$ (28)		$ 247	$ 13
Equity method dividends received				149	158
Reportable Subsegments | Graphic Packaging LLC [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest						20.50%
Equity method investments, aggregate units exchanged		17,399,414	15,150,784			79,911,591
Equity earnings (loss), net of taxes	$ 0	$ 11		4	29
Equity method dividends received				$ 5	16
Reportable Subsegments | Ilim Holding
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest	50.00%			50.00%
Equity earnings (loss), net of taxes	$ 95	(33)		$ 245	(5)
Equity method dividends received				144	141
Foreign currency transaction gain (loss), net of tax		55			72
Equity method investments	517			517			$ 393
Equity method investment, difference between carrying amount and underlying equity	131			131			$ 127
Related party transaction, purchases from related party	$ 42	$ 41		$ 125	$ 131