EQUITY (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Beginning Balance	$ 8,354,000,000	$ 7,060,000,000	$ 7,868,000,000	$ 7,718,000,000
Stockholders' Equity Attributable to Parent	9,622,000,000		9,622,000,000			$ 7,854,000,000
Issuance of stock for various plans, net	41,000,000	20,000,000	113,000,000	65,000,000
Repurchase of stock	(212,000,000)	(1,000,000)	(425,000,000)	(42,000,000)
Common stock dividends	(203,000,000)	(205,000,000)	(612,000,000)	(613,000,000)
Transactions of equity method investees		1,000,000	19,000,000	36,000,000
Noncontrolling Interest, Period Increase (Decrease)	(1,000,000)		(13,000,000)
Comprehensive income (loss), portion attributable to noncontrolling interest	0	0	(2,000,000)	(2,000,000)
Comprehensive Income (Loss)	1,644,000,000	221,000,000	2,673,000,000	(66,000,000)
Stockholders' equity attributable to noncontrolling interest	1,000,000		1,000,000			14,000,000
Ending Balance	9,623,000,000	7,096,000,000	9,623,000,000	7,096,000,000
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2019-05
Beginning Balance				(2,000,000)
Common Stock Issued
Stockholders' Equity Attributable to Parent	449,000,000	449,000,000	449,000,000	449,000,000	$ 449,000,000	449,000,000	$ 449,000,000	$ 449,000,000
Paid-in Capital
Stockholders' Equity Attributable to Parent	6,371,000,000	6,302,000,000	6,371,000,000	6,302,000,000	6,330,000,000	6,325,000,000	6,283,000,000	6,297,000,000
Issuance of stock for various plans, net	41,000,000	18,000,000	27,000,000	(31,000,000)
Transactions of equity method investees		1,000,000	19,000,000	36,000,000
Retained Earnings
Stockholders' Equity Attributable to Parent	9,103,000,000	8,122,000,000	9,103,000,000	8,122,000,000	8,442,000,000	8,070,000,000	8,123,000,000	8,408,000,000
Common stock dividends	(203,000,000)	(205,000,000)	(612,000,000)	(613,000,000)
Comprehensive income (loss)	864,000,000	204,000,000	1,645,000,000	329,000,000
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2019-05
Beginning Balance				(2,000,000)
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity Attributable to Parent	(3,314,000,000)	(5,132,000,000)	(3,314,000,000)	(5,132,000,000)	(4,094,000,000)	(4,342,000,000)	(5,149,000,000)	(4,739,000,000)
Comprehensive income (loss)	780,000,000	17,000,000	1,028,000,000	(393,000,000)
Common Stock Held In Treasury, At Cost
Stockholders' Equity Attributable to Parent	2,987,000,000	2,648,000,000	2,987,000,000	2,648,000,000	2,775,000,000	2,648,000,000	2,649,000,000	2,702,000,000
Issuance of stock for various plans, net	0	(2,000,000)	(86,000,000)	(96,000,000)
Repurchase of stock	212,000,000	1,000,000	425,000,000	42,000,000
Total International Paper Shareholders’ Equity
Stockholders' Equity Attributable to Parent	9,622,000,000	7,093,000,000	9,622,000,000	7,093,000,000	8,352,000,000	7,854,000,000	7,057,000,000	7,713,000,000
Issuance of stock for various plans, net	41,000,000	20,000,000	113,000,000	65,000,000
Repurchase of stock	(212,000,000)	(1,000,000)	(425,000,000)	(42,000,000)
Common stock dividends	(203,000,000)	(205,000,000)	(612,000,000)	(613,000,000)
Transactions of equity method investees		1,000,000	19,000,000	36,000,000
Noncontrolling Interest, Period Increase (Decrease)	0		0
Comprehensive income (loss)	1,644,000,000	221,000,000	2,673,000,000	(64,000,000)
Total International Paper Shareholders’ Equity | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2019-05
Beginning Balance				(2,000,000)
Noncontrolling Interests
Noncontrolling Interest, Period Increase (Decrease)	(1,000,000)		(13,000,000)
Comprehensive income (loss), portion attributable to noncontrolling interest	0	0	0	(2,000,000)
Stockholders' equity attributable to noncontrolling interest	$ 1,000,000	$ 3,000,000	$ 1,000,000	$ 3,000,000	$ 2,000,000	$ 14,000,000	$ 3,000,000	$ 5,000,000