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		Sep. 30, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral Already Posted, Aggregate Fair Value		$ 223		$ 146
Total Mark-to-Market Derivative Assets		13		36
Total Mark-to-Market Derivative (Liabilities)		(15)		(21)
Collateral netted against assets and liabilities		112		44
Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Mark-to-Market Derivative Assets	[1]	13		36
Total Mark-to-Market Derivative (Liabilities)	[1]	(15)		(21)
Collateral netted against assets and liabilities	[1],[2]	112		44
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				223
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				223
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				0
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				0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, Fair Value Disclosure				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				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				223
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				223
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	[3]	12		15
Total Mark-to-Market Derivative (Liabilities)	[3]	(10)		(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	[3]	12		15
Total Mark-to-Market Derivative (Liabilities)	[3]	(10)		(8)
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	[3]	404		442
Total Mark-to-Market Derivative (Liabilities)	[3]	(519)		(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	[3]	404		442
Total Mark-to-Market Derivative (Liabilities)	[3]	(519)		485
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	[3]	8		12
Total Mark-to-Market Derivative (Liabilities)	[3]	(9)		(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	[3]	8		12
Total Mark-to-Market Derivative (Liabilities)	[3]	(9)		(5)
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	[3]	13		36
Total Mark-to-Market Derivative (Liabilities)	[3]	(15)		(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	[3]	13		36
Total Mark-to-Market Derivative (Liabilities)	[3]	(15)		(21)
Cash and Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities				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				0
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	[3],[4]	(411)		(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	[1],[2],[3],[4]	(411)		(433)
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	[3],[4]	523		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	[1],[2],[3],[4]	523		477
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Equity Securities [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Equity Securities [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	1,118		1,145
Equity Securities [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	1,118		1,145
Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	2		2
Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	2		2
Equity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Equity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Equity Securities [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments		1,120	[4]	1,147	[5]
Equity Securities [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	1,120		1,147
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
US Treasury Securities [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
US Treasury Securities [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
US Treasury Securities [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
US Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	209		314
US Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	209		314
US Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
US Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
US Treasury Securities [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments		209	[4]	314	[5]
US Treasury Securities [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	209		314
Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Government Debt Securities [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Government Debt Securities [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Government Debt Securities [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Government Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	311		270
Government Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	311		270
Government Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Government Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Government Debt Securities [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments		311	[4]	270	[5]
Government Debt Securities [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	311		270
Corporate Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Corporate Debt Obligations [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Corporate Debt Obligations [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Corporate Debt Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Corporate Debt Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	456		402
Corporate Debt Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	456		402
Corporate Debt Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Corporate Debt Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Corporate Debt Obligations [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments		456	[4]	402	[5]
Corporate Debt Obligations [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	456		402
Rabbi Trusts Equity Securities Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [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]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	25		27
Rabbi Trusts Equity Securities Mutual Funds [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	6		6
Rabbi Trusts Equity Securities Mutual Funds [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	5		5
Rabbi Trusts Equity Securities Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Equity Securities Mutual Funds [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	25		27
Rabbi Trusts Equity Securities Mutual Funds [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	6		6
Rabbi Trusts Equity Securities Mutual Funds [Member] | Total Estimate Of Fair Value [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	5		5
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	[5]			0
Rabbi Trusts US Treasury Obligations [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts US Treasury Obligations [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]	0		0
Rabbi Trusts US Treasury Obligations [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts US Treasury Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts US Treasury Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts US Treasury Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	60		51
Rabbi Trusts US Treasury Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	15		13
Rabbi Trusts US Treasury Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	12		10
Rabbi Trusts US Treasury Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts US Treasury Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts US Treasury Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts US Treasury Obligations [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	60		51
Rabbi Trusts US Treasury Obligations [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	15		13
Rabbi Trusts US Treasury Obligations [Member] | Total Estimate Of Fair Value [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	12		10
Rabbi Trusts Debt Securities Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts Debt Securities Government Obligations [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts Debt Securities Government Obligations [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]	0		0
Rabbi Trusts Debt Securities Government Obligations [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]			0
Rabbi Trusts Debt Securities Government Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Government Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	39		34
Rabbi Trusts Debt Securities Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	10		8
Rabbi Trusts Debt Securities Government Obligations [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	8		7
Rabbi Trusts Debt Securities Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]			0
Rabbi Trusts Debt Securities Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Government Obligations [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	39		34
Rabbi Trusts Debt Securities Government Obligations [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	10		8
Rabbi Trusts Debt Securities Government Obligations [Member] | Total Estimate Of Fair Value [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	8		7
Rabbi Trusts Debt Securities Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts Debt Securities Other [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral netted against assets and liabilities	[5]	0		0
Rabbi Trusts Debt Securities Other [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]	0		0
Rabbi Trusts Debt Securities Other [Member] | Quoted Market Prices of Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Other [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Other [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Other [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	101		119
Rabbi Trusts Debt Securities Other [Member] | Significant Other Observable Inputs (Level 2) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	26		30
Rabbi Trusts Debt Securities Other [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]
Fair Value, Measured on Recurring Basis, Investments	[5]	21		24
Rabbi Trusts Debt Securities Other [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Other [Member] | Significant Unobservable Inputs (Level 3) [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	0		0
Rabbi Trusts Debt Securities Other [Member] | Total Estimate Of Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	101		119
Rabbi Trusts Debt Securities Other [Member] | Total Estimate Of Fair Value [Member] | Power [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	26		30
Rabbi Trusts Debt Securities Other [Member] | Total Estimate Of Fair Value [Member] | PSE And G [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measured on Recurring Basis, Investments	[5]	$ 21		$ 24

[1] 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 September 30, 2018 and December 31, 2017.

[2] 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 September 30, 2018 and December 31, 2017, Power had net cash collateral/margin payments to counterparties of $223 million and $146 million, respectively. Of these net cash/collateral margin payments $112 million as of September 30, 2018 and $44 million as December 31, 2017 were netted against the corresponding net derivative contract positions. Of the $112 million as of September 30, 2018, $(2) million was netted against current assets, and $(1) million was netted against noncurrent assets, $88 million was netted against current liabilities, and $27 million was netted against noncurrent liabilities. 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.

[3] 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.

[4] Represents the netting of fair value balances with the same counterparty (where the right of offset exists) and the application of collateral.

[5] 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.