Leases (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended
	Apr. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Leases Disclosure [Line Items]
Payment of settlement of an agreement related to the offshore wind installation vessel under development	$ 47
Charge in connection with settlement of an agreement			$ 47
Charge in connection with settlement of an agreement, after tax			$ 35
Power Purchase Arrangement
Leases Disclosure [Line Items]
Rental revenue		$ 6		$ 6	$ 9	$ 11
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]		Revenues		Revenues	Revenues	Revenues
Depreciation expense				$ 2	$ 3	$ 3
Power Purchase Arrangement | Minimum
Leases Disclosure [Line Items]
Depreciation expense		$ 1