Leases (Narrative) (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2024	Mar. 31, 2025	Mar. 31, 2024
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		$ 4	$ 3
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]		Revenues	Revenues
Depreciation expense		$ (1)	$ (3)