Fair Value Measurements (Schedule Of Quantitative Information About Level 3 Fair Value Measurements) (Detail) - USD ($)
$ in Millions |
3 Months Ended |
12 Months Ended |
Mar. 31, 2018 |
Dec. 31, 2017 |
| PSEG [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets, Fair Value |
$ 7
|
$ 12
|
| Liabilities, Fair Value |
0
|
(5)
|
| Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets, Fair Value |
7
|
12
|
| Liabilities, Fair Value |
0
|
(5)
|
| Various [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets, Fair Value |
1
|
11
|
| Liabilities, Fair Value |
0
|
(2)
|
| Electric Load Contracts [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets, Fair Value |
6
|
1
|
| Liabilities, Fair Value |
$ 0
|
$ (3)
|
| Valuation Technique (s) |
Discounted Cash flow
|
Discounted Cash flow
|
| Significant Unobservable Inputs |
Historic Load Variability
|
Historic Load Variability
|
| Electric Load Contracts [Member] | Minimum [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Historic Load Variability |
0.00%
|
0.00%
|
| Electric Load Contracts [Member] | Maximum [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Historic Load Variability |
10.00%
|
10.00%
|
| Gas Physical Contract [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Valuation Technique (s) |
Discounted Cash flow
|
Discounted Cash flow
|
| Significant Unobservable Inputs |
Average Historical Basis
|
Average Historical Basis
|
| Gas Physical Contract [Member] | Minimum [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Average Historical Basis |
(40.00%)
|
(40.00%)
|
| Gas Physical Contract [Member] | Maximum [Member] | Power [Member] |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Average Historical Basis |
0.00%
|
(10.00%)
|