Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred tax liabilities
Property related	$ 1,210	$ 1,121
Pension and postretirement benefits	98	116
Total deferred tax liabilities	1,308	1,237
Deferred tax assets
Loss and credit carryforwards	340	301
Medical benefits	26	27
Insurance reserves	15	16
Pension and postretirement benefits	46	66
Capitalized energy conservation assistance costs	20	18
Other	3	26
Total deferred tax assets	450	454
Total deferred tax liability, net	$ 858	$ 783