Commitments And Contingent Liabilities (Face Value Of Outstanding Guarantees, Current Exposure And Margin Positions) (Detail) - PSEG Power LLC - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Face Value of Outstanding Guarantees	$ 1,792	$ 1,854
Exposure under Current Guarantees	128	171
Letters of Credit Margin Posted	128	121
Letters of Credit Margin Received	45	29
Counterparty Cash Margin Deposited	0	0
Counterparty Cash Margin Received	(5)	(4)
Net Broker Balance Deposited (Received)	59	48
Other Letters of Credit	$ 42	$ 82