GENERAL INFORMATION AND OTHER FINANCIAL DATA - RESTRICTED CASH (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017		Sep. 30, 2017	[2]	Dec. 31, 2016	[2]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 212	$ 288	[1]
Restricted cash, current	73	62	[1]
Restricted cash, noncurrent	3	14	[1]
Total cash, cash equivalents and restricted cash on the Condensed Consolidated Statements of Cash Flows	288	364		$ 261		$ 425
San Diego Gas and Electric Company [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	27	12	[1]
Restricted cash, current	17	6	[1]
Restricted cash, noncurrent	0	11	[1]
Total cash, cash equivalents and restricted cash on the Condensed Consolidated Statements of Cash Flows	$ 44	$ 29		$ 33		$ 20

[1] Derived from audited financial statements.

[2] As adjusted for the retrospective adoption of ASU 2016-15 and ASU 2016-18, which we discuss in Note 2.