Retirement Plans (Effect Of A 25 Basis Point Decrease On Net Pension Expense) (Details) - Domestic Plan [Member] $ in Millions	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Discount rate	$ 27
Expected long-term rate of return on plan assets	$ 22

Defined Benefit Plan Effect Of Twenty Five Basis Points Decrease On Net Periodic Benefit Cost Expected Long Term Return On Assets Estimated For Next Fiscal Year

No definition available.

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Namespace Prefix:	ip_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant