Regulatory - Schedule of Regulatory Assets and Regulatory Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Regulatory assets:
Regulatory assets	$ 1,552	$ 1,002
Less: Current portion	361	136
Long-term regulatory assets	1,191	866
Regulatory liabilities:
Regulatory liabilities	1,140	1,170
Less: Current portion	85	78
Long-term regulatory liabilities	1,055	1,092
Regulatory Tax Asset [Member]
Regulatory assets:
Regulatory assets	124	117
Cost-Recovery Clauses [Member]
Regulatory assets:
Regulatory assets	525	89
Capital Cost Recovery for Early Retired Assets [Member]
Regulatory assets:
Regulatory assets	497	518
Environmental Remediation [Member]
Regulatory assets:
Regulatory assets	20	22
Postretirement Benefits [Member]
Regulatory assets:
Regulatory assets	272	230
Asset Retirement Obligation [Member]
Regulatory assets:
Regulatory assets	13	11
Storm Reserve [Member]
Regulatory assets:
Regulatory assets	76	0
Other [Member]
Regulatory assets:
Regulatory assets	11	2
Regulatory Tax Liability [Member] | Non-Current Liabilities [Member]
Regulatory liabilities:
Regulatory liabilities	601	638
Cost-recovery Clauses - Deferred Balances [Member]
Regulatory liabilities:
Regulatory liabilities	30	16
Accumulated Reserve - Cost of Removal [Member]
Regulatory liabilities:
Regulatory liabilities	498	468
Storm Reserve [Member]
Regulatory liabilities:
Regulatory liabilities	0	46
Other [Member]
Regulatory liabilities:
Regulatory liabilities	$ 25	$ 15