Accumulated Other Comprehensive Loss (Tables)

12 Months Ended

Dec. 31, 2024

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Components of accumulated other comprehensive loss

In millions	Foreign currency translation adjustments		Pension and other postretirement benefit plans		Derivative instruments		Total before tax		Income tax recovery (expense) (1)		Total net of tax
Balance at December 31, 2021	$	(436)	$	(2,419)	$	5	$	(2,850)	$	609	$	(2,241)
Other comprehensive income (loss) before reclassifications:
Translation of net investment (2)	1,073						1,073		—		1,073
Translation of US dollar debt (3)	(707)						(707)		93		(614)
Derivative instruments (4)					(2)		(2)		—		(2)
Actuarial loss arising during the year (5)			(432)				(432)		113		(319)
Prior service credit arising during the year (5)			21				21		(6)		15
Amounts reclassified from Accumulated other comprehensive loss:
Amortization of net actuarial loss			162				162		(43)		119
Amortization of prior service credit			(2)				(2)		1		(1)
Settlement loss arising during the year (6)			1				1		—		1
Other comprehensive income (loss)	366		(250)		(2)		114		158		272
Balance at December 31, 2022	(70)		(2,669)		3		(2,736)		767		(1,969)
Other comprehensive income (loss) before reclassifications:
Translation of net investment (2)	(363)						(363)		—		(363)
Translation of US dollar debt (3)	262						262		(33)		229
Derivative instruments (4)					97		97		(25)		72
Actuarial loss arising during the year			(331)				(331)		86		(245)
Amounts reclassified from Accumulated other comprehensive loss:
Amortization of prior service credit			(3)				(3)		1		(2)
Amortization of gain on treasury lock					(1)		(1)		—		(1)
Other comprehensive income (loss)	(101)		(334)		96		(339)		29		(310)
Balance at December 31, 2023	(171)		(3,003)		99		(3,075)		796		(2,279)
Other comprehensive income (loss) before reclassifications:
Translation of net investment (2)	1,377						1,377		—		1,377
Translation of US dollar debt (3)	(989)						(989)		130		(859)
Derivative instruments (4)					(15)		(15)		4		(11)
Actuarial gain arising during the year			973				973		(255)		718
Amounts reclassified from Accumulated other comprehensive loss:
Amortization of net actuarial loss			56				56		(14)		42
Amortization of prior service credit			(4)				(4)		—		(4)
Amortization of gain on treasury lock					(5)		(5)		1		(4)
Other comprehensive income (loss)	388		1,025		(20)		1,393		(134)		1,259
Balance at December 31, 2024	$	217	$	(1,978)	$	79	$	(1,682)	$	662	$	(1,020)

(1)The Company releases stranded tax effects from Accumulated other comprehensive loss to Net income upon the liquidation or termination of the related item.

(2)Foreign exchange gain/(loss) on translation of net investment in foreign operations.

(3)Foreign exchange gain/(loss) on translation of US dollar-denominated debt designated as a hedge of the net investment in foreign operations. The Company designates US dollar-denominated debt of the parent company as a foreign currency hedge of its net investment in foreign operations. Accordingly, from the dates of designation, foreign exchange gains and losses on translation of the Company's US dollar-denominated debt are recorded in Accumulated other comprehensive loss, which minimizes the volatility of earnings resulting from the conversion of US dollar-denominated debt into Canadian dollars.

(4)Cumulative gains or losses of the treasury locks are included in Derivative instruments. See Note 22 – Financial instruments for additional information.

(5)Amendments to the postretirement medical benefits plans in the U.S. resulted in a prior service credit of $21 million and an actuarial gain of $7 million. See Note 17 – Pensions and other postretirement benefits for additional information.

(6)Total before tax reclassified to Other components of net periodic benefit cost (income) in the Consolidated Statements of Income and included in net periodic benefit cost (income). See Note 17 – Pensions and other postretirement benefits.