Income Taxes - Schedule of Components of Net Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Aug. 01, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Deferred tax assets, Tax loss carryforwards	$ 2,218		$ 2,042
Deferred tax assets, Employee benefits	312		312
Deferred tax assets, Derivatives and hedging activities	248		312
Deferred tax assets, Loss provisions	166		161
Deferred tax assets, Interest	142		142
Deferred tax assets, Depreciation	83		94
Deferred tax assets, Lease assets	74		34
Deferred tax assets, Investment basis differences	73		78
Deferred tax assets, Tax credit carryforwards	23		24
Deferred tax assets, Deferred income/expense	15		16
Deferred tax assets, Other	69		25
Deferred tax assets, Gross	3,423		3,240
Deferred tax assets, Valuation allowance	(2,734)		(2,595)	$ (2,333)	$ (2,062)
Total	689	$ 121	645
Deferred tax liabilities, Tax loss carryforwards	0		0
Deferred tax liabilities, Employee benefits	0		0
Deferred tax liabilities, Derivatives and hedging activities	5		10
Deferred tax liabilities, Loss provisions	0		0
Deferred tax liabilities, Interest	5		6
Deferred tax liabilities, Depreciation	202		318
Deferred tax liabilities, Lease liabilities	73		33
Deferred tax liabilities, Investment basis differences	0		0
Deferred tax liabilities, Tax credit carryforwards	0		0
Deferred tax liabilities, Deferred income/expense	119		131
Deferred tax liabilities, Other	1		0
Deferred tax liabilities, Gross	405		498
Deferred tax liabilities, Valuation allowance	0		0
Total	$ 405		$ 498