Variable Interest Entities (VIEs) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Operating Revenues	$ 2,096	$ 2,263	$ 2,133	$ 2,592	$ 2,090	$ 2,450	$ 1,905	$ 2,616	$ 9,084	$ 9,061	$ 10,415
Operation and Maintenance									2,869	3,008	2,978
PSE&G [Member]
Variable Interest Entity [Line Items]
Operating Revenues	$ 1,545	$ 1,509	$ 1,368	$ 1,812	$ 1,475	$ 1,684	$ 1,350	$ 1,712	6,234	6,221	6,636
Operation and Maintenance									1,434	1,475	1,560
Long Island ServCo [Member]
Variable Interest Entity [Line Items]
Operating Revenues									438	410	375
Operation and Maintenance									$ 438	$ 410	$ 375