Fair Value Measurements (Fair Value Of Debt) (Detail) - USD ($)
$ in Millions
Mar. 31, 2018
Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-Term Debt, Carrying Amount $ 13,072 $ 13,068
Long-Term Debt, Fair Value 13,522 14,062
Power - Recourse Debt [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-Term Debt, Carrying Amount [1] 2,387 2,386
Long-Term Debt, Fair Value [1] 2,566 2,659
PSE And G [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-Term Debt, Carrying Amount [1] 8,593 8,591
Long-Term Debt, Fair Value [1] 8,908 9,322
PSEG [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Long-Term Debt, Carrying Amount [1],[2] 2,092 2,091
Long-Term Debt, Fair Value [1],[2] 2,048 $ 2,081
Variable Rate [Domain] | PSEG [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Floating Rate Term Loan $ 700  
[1] Given that these bonds do not trade actively, the fair value amounts of taxable debt securities (primarily Level 2 measurements) are generally determined by a valuation model that is based on a conventional discounted cash flow methodology and utilizes assumptions of current market pricing curves. In order to incorporate the credit risk into the discount rates, pricing is obtained (i.e. U.S. Treasury rate plus credit spread) based on expected new issue pricing across each of the companies’ respective debt maturity spectrum. The credit spreads of various tenors obtained from this information are added to the appropriate benchmark U.S. Treasury rates in order to determine the current market yields for the various tenors. The yields are then converted into discount rates of various tenors that are used for discounting the respective cash flows of the same tenor for each bond or note.
[2] Includes floating rate term loans of $700 million. The fair values of the term loan debt (Level 2 measurement) approximate the carrying values because the interest payments are based on LIBOR rates that are reset monthly and the debt is redeemable at face value by PSEG at any time.