Income taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Company retirement benefit plans	$ 0	$ 2
Revaluation of derivative financial instruments to fair value	5	4
Tax losses, credits and interest deduction carryforwards	1,507	1,149
Share-based compensation	40	39
Accrued expenses	345	454
Lease liabilities	423	286
Other	8	0
Total deferred tax assets	2,328	1,934
Less: valuation allowances	(1,336)	(1,059)	$ (914)	$ (737)
Total deferred tax assets after valuation allowances	992	875
Deferred tax liabilities:
Company retirement benefit plans	22	0
Investment in subsidiaries	162	146
Depreciation, depletion and amortization	3,772	3,419
Leased right-of-use assets	401	278
Rolled-over capital gains	26	21
Other	0	15
Total deferred tax liabilities	4,383	3,879
Total net deferred tax liabilities	$ 3,391	$ 3,004