GENERAL INFORMATION AND OTHER FINANCIAL DATA - RESTRICTED CASH (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017		Mar. 31, 2017	[2]	Dec. 31, 2016	[2]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 239	$ 288	[1]
Restricted cash, current	54	62	[1]
Restricted cash, noncurrent	14	14	[1]
Total cash, cash equivalents and restricted cash on the Condensed Consolidated Statement of Cash Flows	307	364		$ 367		$ 425
San Diego Gas and Electric Company [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	9	12	[1]
Restricted cash, current	5	6	[1]
Restricted cash, noncurrent	11	11	[1]
Total cash, cash equivalents and restricted cash on the Condensed Consolidated Statement of Cash Flows	$ 25	$ 29		$ 31		$ 20

[1] Derived from audited financial statements.

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