Fair Value Measurements (PSEG's, Power's And PSE&G's Respective Assets And (Liabilities) Measured At Fair Value On A Recurring Basis) (Detail) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral Already Posted, Aggregate Fair Value $ 121 $ 146
Total Mark-to-Market Derivative Assets 91 36
Total Mark-to-Market Derivative (Liabilities) (12) (21)
Collateral netted against assets and liabilities (2) 44
Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1]   0
Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [2] 91 36
Total Mark-to-Market Derivative (Liabilities) [2] (12) (21)
Collateral netted against assets and liabilities [2],[3] (2) 44
Power [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Power [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
PSE And G [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
PSE And G [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
PSE And G [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
PSE And G [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   223
Quoted Market Prices of Identical Assets (Level 1) [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 1,084 1,145
Quoted Market Prices of Identical Assets (Level 1) [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 23 27
Quoted Market Prices of Identical Assets (Level 1) [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1]   0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 1,084 1,145
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 6 6
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   223
Quoted Market Prices of Identical Assets (Level 1) [Member] | PSE And G [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 4 5
Quoted Market Prices of Identical Assets (Level 1) [Member] | PSE And G [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Quoted Market Prices of Identical Assets (Level 1) [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Other Observable Inputs (Level 2) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   0
Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 2 2
Significant Other Observable Inputs (Level 2) [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 285 270
Significant Other Observable Inputs (Level 2) [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 223 314
Significant Other Observable Inputs (Level 2) [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 456 402
Significant Other Observable Inputs (Level 2) [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Other Observable Inputs (Level 2) [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 54 51
Significant Other Observable Inputs (Level 2) [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 35 34
Significant Other Observable Inputs (Level 2) [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 113 119
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 2 2
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 285 270
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 223 314
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 456 402
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 13 13
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 9 8
Significant Other Observable Inputs (Level 2) [Member] | Power [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 28 30
Significant Other Observable Inputs (Level 2) [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   0
Significant Other Observable Inputs (Level 2) [Member] | PSE And G [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Other Observable Inputs (Level 2) [Member] | PSE And G [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 11 10
Significant Other Observable Inputs (Level 2) [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 7 7
Significant Other Observable Inputs (Level 2) [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 23 24
Significant Unobservable Inputs (Level 3) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   0
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1]   0
Significant Unobservable Inputs (Level 3) [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | Power [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   0
Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 0 0
Total Estimate Of Fair Value [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   223
Total Estimate Of Fair Value [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments 1,086 [5] 1,147 [1]
Total Estimate Of Fair Value [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments 285 [5] 270 [1]
Total Estimate Of Fair Value [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments 223 [5] 314 [1]
Total Estimate Of Fair Value [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments 456 [5] 402 [1]
Total Estimate Of Fair Value [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 23 27
Total Estimate Of Fair Value [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 54 51
Total Estimate Of Fair Value [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 35 34
Total Estimate Of Fair Value [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 113 119
Total Estimate Of Fair Value [Member] | Power [Member] | Equity Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 1,086 1,147
Total Estimate Of Fair Value [Member] | Power [Member] | Government [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 285 270
Total Estimate Of Fair Value [Member] | Power [Member] | US Treasury Securities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 223 314
Total Estimate Of Fair Value [Member] | Power [Member] | Corporate [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 456 402
Total Estimate Of Fair Value [Member] | Power [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 6 6
Total Estimate Of Fair Value [Member] | Power [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 13 13
Total Estimate Of Fair Value [Member] | Power [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 9 8
Total Estimate Of Fair Value [Member] | Power [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 28 30
Total Estimate Of Fair Value [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash Equivalents, Fair Value Disclosure [4]   223
Total Estimate Of Fair Value [Member] | PSE And G [Member] | Rabbi Trust - Equity Securities-Mutual Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 4 5
Total Estimate Of Fair Value [Member] | PSE And G [Member] | Rabbi Trusts US Treasury Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 11 10
Total Estimate Of Fair Value [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Govt Obligations [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 7 7
Total Estimate Of Fair Value [Member] | PSE And G [Member] | Rabbi Trust - Debt Securities-Other [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value, Measured on Recurring Basis, Investments [1] 23 24
Energy-Related Contracts [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 10 15
Total Mark-to-Market Derivative (Liabilities) [6] (6) 8
Energy-Related Contracts [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member] | Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 10 15
Total Mark-to-Market Derivative (Liabilities) [6] (6) 8
Energy-Related Contracts [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6]   0
Total Mark-to-Market Derivative (Liabilities) [6]   0
Energy-Related Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 505 442
Total Mark-to-Market Derivative (Liabilities) [6] (435) (485)
Energy-Related Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 505 442
Total Mark-to-Market Derivative (Liabilities) [6] (435) 485
Energy-Related Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6]   0
Total Mark-to-Market Derivative (Liabilities) [6]   0
Energy-Related Contracts [Member] | Significant Unobservable Inputs (Level 3) [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 7 12
Total Mark-to-Market Derivative (Liabilities) [6] 0 (5)
Energy-Related Contracts [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 7 12
Total Mark-to-Market Derivative (Liabilities) [6] 0 5
Energy-Related Contracts [Member] | Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6]   0
Total Mark-to-Market Derivative (Liabilities) [6]   0
Energy-Related Contracts [Member] | Total Estimate Of Fair Value [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 91 36
Total Mark-to-Market Derivative (Liabilities) [6] (12) (21)
Energy-Related Contracts [Member] | Total Estimate Of Fair Value [Member] | Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6] 91 36
Total Mark-to-Market Derivative (Liabilities) [6] (12) (21)
Energy-Related Contracts [Member] | Total Estimate Of Fair Value [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Total Mark-to-Market Derivative Assets [6]   0
Total Mark-to-Market Derivative (Liabilities) [6]   0
Cash and Cash Equivalents [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [4]   0
Cash and Cash Equivalents [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [4]   0
Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities   (3)
Assets [Member] | Energy-Related Contracts [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [5],[6] (431) (433)
Assets [Member] | Energy-Related Contracts [Member] | Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [2],[3],[5],[6] (431) (433)
Assets [Member] | Energy-Related Contracts [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [5],[6]   0
Other Liabilities [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities   47
Other Liabilities [Member] | Energy-Related Contracts [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [5],[6] 429 477
Other Liabilities [Member] | Energy-Related Contracts [Member] | Power [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [2],[3],[5],[6] $ 429 477
Other Liabilities [Member] | Energy-Related Contracts [Member] | PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Collateral netted against assets and liabilities [5],[6]   $ 0
[1] The NDT Fund maintains investments in various equity and fixed income securities. The Rabbi Trust maintains investments in various fixed income securities and a Russell 3000 index fund. These securities are generally valued with prices that are either exchange provided (equity securities) or market transactions for comparable securities and/or broker quotes (fixed income securities).Level 1—Investments in marketable equity securities within the NDT Fund are primarily investments in common stocks across a broad range of industries and sectors. Most equity securities are priced utilizing the principal market close price or, in some cases, midpoint, bid or ask price. Certain other equity securities in the NDT and Rabbi Trust Funds consist primarily of investments in Dreyfus money market funds which seek a high level of current income as is consistent with the preservation of capital and the maintenance of liquidity. To pursue its goals, the funds normally invest in diversified portfolios of high quality, short-term, dollar-denominated debt securities and government securities. The funds’ Net Asset Value is priced and published daily. The Rabbi Trust also has an equity index fund which is valued based on quoted prices in an active market.Level 2—NDT and Rabbi Trust fixed income securities include investment grade corporate bonds, collateralized mortgage obligations, asset-backed securities and certain government and U.S. Treasury obligations or Federal Agency asset-backed securities and municipal bonds with a wide range of maturities. Since many fixed income securities do not trade on a daily basis, they are priced using an evaluated pricing methodology that varies by asset class and reflects observable market information such as the most recent exchange price or quoted bid for similar securities. Market-based standard inputs typically include benchmark yields, reported trades, broker/dealer quotes and issuer spreads. The preferred stocks are not actively traded on a daily basis and therefore, are also priced using an evaluated pricing methodology. Certain short-term investments are valued using observable market prices or market parameters such as time-to-maturity, coupon rate, quality rating and current yield.
[2] Substantially all of Power’s derivative instruments are contracts subject to master netting agreements. Contracts not subject to master netting or similar agreements are immaterial and did not have any collateral posted or received as of March 31, 2018 and December 31, 2017.
[3] Represents the netting of fair value balances with the same counterparty (where the right of offset exists) and the application of collateral. All cash collateral received or posted that has been allocated to derivative positions, where the right of offset exists, has been offset on the Condensed Consolidated Balance Sheets. As of March 31, 2018 and December 31, 2017, Power had net cash collateral/margin payments to counterparties of $121 million and $146 million, respectively. Of these net cash/collateral margin payments $(2) million as of March 31, 2018 and $44 million as December 31, 2017 were netted against the corresponding net derivative contract positions. The $(2) million as of March 31, 2018 was netted against current assets. Of the $44 million as of December 31, 2017, $(3) million was netted against current assets, $28 million was netted against current liabilities, and $19 million was netted against noncurrent liabilities.
[4] Represents money market mutual funds.
[5] Represents the netting of fair value balances with the same counterparty (where the right of offset exists) and the application of collateral. All cash collateral received or posted that has been allocated to derivative positions, where the right of offset exists, has been offset in the Condensed Consolidated Balance Sheets. As of March 31, 2018 and December 31, 2017, Power had net cash collateral/margin payments to counterparties of $121 million and $146 million, respectively. Of these net cash collateral/margin payments $(2) million as of March 31, 2018 and $44 million as of December 31, 2017 were netted against the corresponding net derivative contract positions. The $(2) million of cash collateral as of March 31, 2018 was netted against assets. Of the $44 million of cash collateral as of December 31, 2017, $(3) million was netted against assets and $47 million was netted against liabilities.
[6] Level 1—These contracts represent natural gas futures contracts executed on NYMEX, and are being valued solely on settled pricing inputs which come directly from the exchange.Level 2—Fair values for energy-related contracts are obtained primarily using a market-based approach. Most derivative contracts (forward purchase or sale contracts and swaps) are valued using settled prices from similar assets and liabilities from an exchange, such as NYMEX, ICE and Nodal Exchange, or auction prices. Prices used in the valuation process are also corroborated independently by management to determine that values are based on actual transaction data or, in the absence of transactions, bid and offers for the day. Examples may include certain exchange and non-exchange traded capacity and electricity contracts and natural gas physical or swap contracts based on market prices, basis adjustments and other premiums where adjustments and premiums are not considered significant to the overall inputs.Level 3—Unobservable inputs are used for the valuation of certain contracts. See “Additional Information Regarding Level 3 Measurements” below for more information on the utilization of unobservable inputs.