Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Federal income tax rate	21.00%	21.00%	35.00%
Provisional Deferred Tax Benefit	$ 0	$ 3	$ (755)
Regulatory Liabilities	$ 3,002	3,221
NJ surcharge tax percent for 2018 to 2019	2.50%
NJ tax surcharge percent for 2020 to 2021	1.50%
Tax Adjustment Credit	$ (272)	(30)	0
Public Service Electric and Gas Company
Income Taxes [Line Items]
Provisional Deferred Tax Benefit	0	0	(10)
Regulatory Liabilities	3,002	3,221
NOL Carryforwards	16
Excess deferred income tax flowback	380
Tax Adjustment Credit	(272)	(30)	$ 0
Excess Deferred Income Taxes excluding amounts from previously realized repair deductions [Member] | Public Service Electric and Gas Company
Income Taxes [Line Items]
Reduction in Regulatory Liability	$ 321
Reduction in Deferred Tax Liabilities		2,100
Regulatory Liabilities		$ 2,900