Earnings Per Share Attributable To International Paper Company Common Shareholders (Reconciliation Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[2]	Sep. 30, 2017	[2]	Jun. 30, 2017	[2]	Mar. 31, 2017	[2]	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Earnings Per Share, Basic and Diluted [Line Items]
Earnings (loss) from continuing operations																	$ 1,667		$ 2,110		$ 802
Weighted average common shares outstanding																	409.1		412.7		411.1
Weighted average common shares outstanding – assuming dilution																	414.2		417.7		415.6
Basic earnings (loss) per share from continuing operations	$ 0.79		$ 1.38		$ 1.03		$ 0.87		$ 3.56		$ 0.89		$ 0.20		$ 0.47		$ 4.07	[1]	$ 5.11	[2]	$ 1.95
Diluted earnings (loss) per share from continuing operations	$ 0.78		$ 1.37		$ 1.02		$ 0.86		$ 3.52		$ 0.88		$ 0.20		$ 0.46		$ 4.02	[1]	$ 5.05	[2]	$ 1.93
Restricted performance share plan
Earnings Per Share, Basic and Diluted [Line Items]
Effect of dilutive securities:																	5.1		5.0		4.5

[1] Includes the following pre-tax charges (gains): 2018In millions Q1 Q2 Q3 Q4Smurfit-Kappa acquisition proposal costs $— $12 $— $—Legal settlement 9 — — —Litigation settlement recovery — — — (5)Environmental remediation reserve adjustment — — 9 —EMEA Packaging optimization 22 26 — (1)Abandoned property removal 9 9 6 8Riverdale mill conversion costs — — 5 4Brazil Packaging impairment — — 122 —Debt extinguishment costs — — — 10Gain on sale of investment in Liaison Technologies — — — (31)Non-operating pension expense 4 36 25 429Total $44 $83 $167 $414

[2] Includes the following pre-tax charges (gains): 2017In millions Q1 Q2 Q3 Q4Gain on sale of investment in ArborGen $— $(14) $— $—Costs associated with the pulp business acquired in 2016 4 5 6 18Amortization of Weyerhaeuser inventory fair value step-up 14 — — —Holmen bargain purchase gain (6) — — —Abandoned property removal 2 5 7 6Kleen Products settlement — 354 — —Asia Foodservice sale — 9 — —Brazil Packaging wood supply accelerated amortization — — 10 —Debt extinguishment costs — — — 83Interest income on income tax refund claims — (4) — (1)Other items — (2) — —Non-operating pension expense 31 34 33 386Total $45 $387 $56 $492