Financing Receivables (Outstanding Loans by Class of Customer) (Detail) - PSE And G [Member] - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Outstanding Loans by Class of Customer	$ 170	$ 175
Commercial/Industrial [Member]
Concentration Risk [Line Items]
Outstanding Loans by Class of Customer	160	164
Residential [Member]
Concentration Risk [Line Items]
Outstanding Loans by Class of Customer	$ 10	$ 11

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_LoansReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant