Income Taxes - Schedule of Components of Net Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Deferred tax assets, Tax loss carryforwards	$ 2,042	$ 1,781
Deferred tax assets, Employee benefits	312	297
Deferred tax assets, Derivatives and hedging activities	312	283
Deferred tax assets, Loss provisions	161	174
Deferred tax assets, Depreciation	94	128
Deferred tax assets, Interest	142	127
Deferred tax assets, Investment basis differences	78	75
Deferred tax assets, Lease assets	34	24
Deferred tax assets, Tax credit carryforwards	24	23
Deferred tax assets, Deferred income/expense	16	10
Deferred tax assets, Other	25	36
Deferred tax assets, Gross	3,240	2,958
Deferred tax assets, Valuation allowance	(2,595)	(2,333)	$ (2,062)	$ (2,127)
Total	645	625
Deferred tax liabilities, Tax loss carryforwards	0	0
Deferred tax liabilities, Employee benefits	0	0
Deferred tax liabilities, Derivatives and hedging activities	10	24
Deferred tax liabilities, Loss provisions	0	0
Deferred tax liabilities, Depreciation	318	336
Deferred tax liabilities, Interest	6	2
Deferred tax liabilities, Investment basis differences	0	0
Deferred tax liabilities, Lease liabilities	33	23
Deferred tax liabilities, Tax credit carryforwards	0	0
Deferred tax liabilities, Deferred income/expense	131	153
Deferred tax liabilities, Other	0	0
Deferred tax liabilities, Gross	498	538
Deferred tax liabilities, Valuation allowance	0	0
Total	$ 498	$ 538