EQUITY (Details) - USD ($)	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Beginning Balance	$ 7,060,000,000	$ 7,718,000,000	$ 7,499,000,000	$ 7,383,000,000	$ 7,718,000,000	$ 7,383,000,000
Stockholders' Equity Attributable to Parent	7,093,000,000				7,093,000,000			$ 7,713,000,000
Issuance of stock for various plans, net	20,000,000		33,000,000		65,000,000	113,000,000
Repurchase of stock	(1,000,000)		(75,000,000)		(42,000,000)	(535,000,000)
Common stock dividends	(205,000,000)		(199,000,000)		(613,000,000)	(607,000,000)
Transactions of equity method investees	1,000,000		0		36,000,000	33,000,000
Comprehensive income (loss), portion attributable to noncontrolling interest	0		0		(2,000,000)	0
Comprehensive income (loss)	221,000,000		198,000,000		(66,000,000)	1,069,000,000
Stockholders' equity attributable to noncontrolling interest	3,000,000				3,000,000			5,000,000
Ending Balance	7,096,000,000		7,456,000,000		7,096,000,000	7,456,000,000
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Financial Instruments, Credit Losses, Impact on Retained Earnings		(2,000,000)
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-02
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect				0
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	6,302,000,000		6,261,000,000		6,302,000,000	6,261,000,000	6,283,000,000	6,297,000,000	6,229,000,000	6,280,000,000
Issuance of stock for various plans, net	18,000,000		32,000,000		(31,000,000)	(52,000,000)
Transactions of equity method investees	1,000,000		0		36,000,000	33,000,000
Retained Earnings
Stockholders' Equity Attributable to Parent	8,122,000,000		8,447,000,000		8,122,000,000	8,447,000,000	8,123,000,000	8,408,000,000	8,302,000,000	7,465,000,000
Common stock dividends	(205,000,000)		(199,000,000)		(613,000,000)	(607,000,000)
Comprehensive income (loss)	204,000,000		344,000,000		329,000,000	1,060,000,000
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Financial Instruments, Credit Losses, Impact on Retained Earnings		(2,000,000)
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-02
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect				529,000,000
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity Attributable to Parent	(5,132,000,000)		(5,014,000,000)		(5,132,000,000)	(5,014,000,000)	(5,149,000,000)	(4,739,000,000)	(4,870,000,000)	(4,500,000,000)
Comprehensive income (loss)	17,000,000		(144,000,000)		(393,000,000)	15,000,000
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2018-02
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect				$ (529,000,000)
Common Stock Held In Treasury, At Cost
Stockholders' Equity Attributable to Parent	2,648,000,000		2,702,000,000		2,648,000,000	2,702,000,000	2,649,000,000	2,702,000,000	2,628,000,000	2,332,000,000
Issuance of stock for various plans, net	(2,000,000)		(1,000,000)		(96,000,000)	(165,000,000)
Repurchase of stock	1,000,000		75,000,000		42,000,000	535,000,000
Total International Paper Shareholders’ Equity
Stockholders' Equity Attributable to Parent	7,093,000,000		7,441,000,000		7,093,000,000	7,441,000,000	7,057,000,000	7,713,000,000	7,482,000,000	7,362,000,000
Issuance of stock for various plans, net	20,000,000		33,000,000		65,000,000	113,000,000
Repurchase of stock	(1,000,000)		(75,000,000)		(42,000,000)	(535,000,000)
Common stock dividends	(205,000,000)		(199,000,000)		(613,000,000)	(607,000,000)
Transactions of equity method investees	1,000,000		0		36,000,000	33,000,000
Comprehensive income (loss)	221,000,000		200,000,000		(64,000,000)	1,075,000,000
Total International Paper Shareholders’ Equity | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Financial Instruments, Credit Losses, Impact on Retained Earnings		$ (2,000,000)
Noncontrolling Interests
Comprehensive income (loss), portion attributable to noncontrolling interest	0		(2,000,000)		(2,000,000)	(6,000,000)
Stockholders' equity attributable to noncontrolling interest	$ 3,000,000		$ 15,000,000		$ 3,000,000	$ 15,000,000	$ 3,000,000	$ 5,000,000	$ 17,000,000	$ 21,000,000