General Information - Narrative (Details) shares in Millions				3 Months Ended							9 Months Ended		24 Months Ended
	Aug. 13, 2020 USD ($) shares	Apr. 01, 2020 facility	Jan. 29, 2020 USD ($) shares	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	[1]	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	[2]	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 shares	Jan. 28, 2020	Jan. 01, 2018
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Shares repurchased (in shares) | shares	17.4		15.1										20.8
Cash paid for repurchase of common stock | $	$ 250,000,000		$ 250,000,000	$ 94,100,000	$ 33,100,000	$ 124,400,000		$ 18,300,000	$ 59,500,000			$ 50,100,000
Shares required to be redeemed in cash | shares	3.1
Number of converting facilities | facility		7
International Paper Company
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of days after exchange											180 days
Dollar limit per unit exchange (lesser of) | $											$ 250,000,000
Percentage limit per unit exchange (lesser of)											25.00%
International Paper Company
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
IP's ownership interest in GPIP	14.50%		18.30%										21.60%	21.60%	20.50%

[1] Includes 410,400 shares repurchased but not yet settled as of March 31, 2020. ^(b) Includes 14,436 shares repurchased but not yet settled as of June 30, 2020. ^(c) Includes 308,185 shares repurchased but not yet settled as of September 30, 2020.

[2] Includes 33,263 shares repurchased but not yet settled as of March 31, 2019.