CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets, Current [Abstract]
Cash and cash equivalents	$ 288	$ 349	[1]
Restricted cash	62	66	[1]
Accounts receivable – trade, net	1,307	1,390	[1]
Accounts receivable – other, net	277	164	[1]
Due from unconsolidated affiliates	37	26	[1]
Income taxes receivable	110	43	[1]
Inventories	307	258	[1]
Regulatory assets	325	348	[1]
Fixed-price contracts and other derivatives	66	83	[1]
Greenhouse gas allowances	299	40	[1]
Assets held for sale	127	201	[1]
Other	136	142	[1]
Total current assets	3,341	3,110	[1]
Other Assets [Abstract]
Restricted cash	14	10	[1]
Due from unconsolidated affiliates	598	201	[1]
Regulatory assets	1,517	3,414	[1]
Nuclear decommissioning trusts	1,033	1,026	[1]
Investments	2,527	2,097	[1]
Goodwill	2,397	2,364	[1]
Other intangible assets	596	548	[1]
Dedicated assets in support of certain benefit plans	455	430	[1]
Insurance receivable for Aliso Canyon costs	418	606	[1]
Deferred income taxes	170	234	[1]
Greenhouse gas allowances	93	295	[1]
Sundry	792	520	[1]
Total other assets	10,610	11,745	[1]
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment	48,108	43,624	[1]
Less accumulated depreciation and amortization	(11,605)	(10,693)	[1]
Property, plant and equipment, net	36,503	32,931	[1]
Total assets	50,454	47,786	[1]
Liabilities, Current [Abstract]
Short-term debt	1,540	1,779	[1]
Accounts payable – trade	1,350	1,346	[1]
Accounts payable – other	173	130	[1]
Due to unconsolidated affiliates	7	11	[1]
Dividends and interest payable	342	319	[1]
Accrued compensation and benefits	439	409	[1]
Regulatory liabilities	109	122	[1]
Current portion of long-term debt	1,427	913	[1]
Fixed-price contracts and other derivatives	109	83	[1]
Customer deposits	162	158	[1]
Reserve for Aliso Canyon costs	84	53	[1]
Greenhouse gas obligations	299	40	[1]
Liabilities held for sale	49	47	[1]
Other	545	517	[1]
Total current liabilities	6,635	5,927	[1]
Long-term debt	16,445	14,429	[1]
Deferred Credits and Other Liabilities [Abstract]
Customer advances for construction	150	152	[1]
Due to unconsolidated affiliates	35	0	[1]
Pension and other postretirement benefit plan obligations, net of plan assets	1,148	1,208	[1]
Deferred income taxes	2,767	3,745	[1]
Deferred investment tax credits	28	28	[1]
Regulatory liabilities	3,922	2,876	[1]
Asset retirement obligations	2,732	2,431	[1]
Fixed-price contracts and other derivatives	316	405	[1]
Greenhouse gas obligations	0	171	[1]
Deferred credits and other	1,136	1,173	[1]
Total deferred credits and other liabilities	12,234	12,189	[1]
Commitments and contingencies (Note 15)			[1]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred stock	0	0	[1]
Common stock	3,149	2,982	[1]
Retained earnings	10,147	10,717	[1]
Accumulated other comprehensive income (loss)	(626)	(748)	[1]
Total shareholders’ equity	12,670	12,951	[1]
Preferred stock of subsidiary	20	20	[1]
Other noncontrolling interests	2,450	2,270	[1]
Total equity	15,140	15,241	[1]
Total liabilities and equity	50,454	47,786	[1]
San Diego Gas and Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents	12	8	[1]
Restricted cash	6	11	[1]
Accounts receivable – trade, net	362	354	[1]
Accounts receivable – other, net	79	17	[1]
Due from unconsolidated affiliates	0	4	[1]
Income taxes receivable	0	122	[1]
Inventories	105	80	[1]
Regulatory assets	316	340	[1]
Prepaid expenses	58	59	[1]
Fixed-price contracts and other derivatives	42	58	[1]
Greenhouse gas allowances	116	16	[1]
Other	4	3	[1]
Total current assets	1,100	1,072	[1]
Other Assets [Abstract]
Restricted cash	11	1	[1]
Regulatory assets	451	2,012	[1]
Nuclear decommissioning trusts	1,033	1,026	[1]
Greenhouse gas allowances	83	182	[1]
Sundry	328	176	[1]
Total other assets	1,906	3,397	[1]
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment	19,787	17,844	[1]
Less accumulated depreciation and amortization	(4,949)	(4,594)	[1]
Property, plant and equipment, net	14,838	13,250	[1]
Total assets	17,844	17,719	[1]
Liabilities, Current [Abstract]
Short-term debt	253	0	[1]
Accounts payable – trade	501	460	[1]
Due to unconsolidated affiliates	40	15	[1]
Interest payable	41	40	[1]
Accrued compensation and benefits	122	121	[1]
Regulatory liabilities	18	0	[1]
Accrued franchise fees	59	43	[1]
Current portion of long-term debt	220	191	[1]
Fixed-price contracts and other derivatives	60	61	[1]
Asset retirement obligations	77	79	[1]
Customer deposits	69	76	[1]
Greenhouse gas obligations	116	16	[1]
Other	46	66	[1]
Total current liabilities	1,622	1,168	[1]
Long-term debt	5,335	4,658	[1]
Deferred Credits and Other Liabilities [Abstract]
Customer advances for construction	57	52	[1]
Pension and other postretirement benefit plan obligations, net of plan assets	182	232	[1]
Deferred income taxes	1,530	2,829	[1]
Deferred investment tax credits	18	16	[1]
Regulatory liabilities	2,225	1,725	[1]
Asset retirement obligations	762	751	[1]
Fixed-price contracts and other derivatives	153	189	[1]
Greenhouse gas obligations	0	72	[1]
Deferred credits and other	334	349	[1]
Total deferred credits and other liabilities	5,261	6,215	[1]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred stock	0	0	[1]
Common stock	1,338	1,338	[1]
Retained earnings	4,268	4,311	[1]
Accumulated other comprehensive income (loss)	(8)	(8)	[1]
Total shareholders’ equity	5,598	5,641	[1]
Other noncontrolling interests	28	37	[1]
Total equity	5,626	5,678	[1]
Total liabilities and equity	17,844	17,719	[1]
Southern California Gas Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents	8	12	[1]
Accounts receivable – trade, net	517	608	[1]
Accounts receivable – other, net	90	77	[1]
Due from unconsolidated affiliates	4	8	[1]
Income taxes receivable	10	2	[1]
Inventories	124	58	[1]
Regulatory assets	9	8	[1]
Greenhouse gas allowances	179	24	[1]
Other	38	39	[1]
Total current assets	979	836	[1]
Other Assets [Abstract]
Regulatory assets	983	1,331	[1]
Insurance receivable for Aliso Canyon costs	418	606	[1]
Greenhouse gas allowances	9	109	[1]
Sundry	364	290	[1]
Total other assets	1,774	2,336	[1]
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment	16,772	15,344	[1]
Less accumulated depreciation and amortization	(5,366)	(5,092)	[1]
Property, plant and equipment, net	11,406	10,252	[1]
Total assets	14,159	13,424	[1]
Liabilities, Current [Abstract]
Short-term debt	116	62	[1]
Accounts payable – trade	502	481	[1]
Accounts payable – other	93	74	[1]
Due to unconsolidated affiliates	35	28	[1]
Accrued compensation and benefits	151	150	[1]
Regulatory liabilities	91	122	[1]
Current portion of long-term debt	501	0	[1]
Customer deposits	89	76	[1]
Reserve for Aliso Canyon costs	84	53	[1]
Greenhouse gas obligations	179	24	[1]
Other	205	171	[1]
Total current liabilities	2,046	1,241	[1]
Long-term debt	2,485	2,982	[1]
Deferred Credits and Other Liabilities [Abstract]
Customer advances for construction	92	99	[1]
Pension obligation, net of plan assets	789	762	[1]
Deferred income taxes	995	1,709	[1]
Deferred investment tax credits	10	12	[1]
Regulatory liabilities	1,697	1,151	[1]
Asset retirement obligations	1,885	1,616	[1]
Greenhouse gas obligations	0	96	[1]
Deferred credits and other	253	246	[1]
Total deferred credits and other liabilities	5,721	5,691	[1]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred stock	22	22	[1]
Common stock	866	866	[1]
Retained earnings	3,040	2,644	[1]
Accumulated other comprehensive income (loss)	(21)	(22)	[1]
Total shareholders’ equity	3,907	3,510	[1]
Total equity	3,907	3,510
Total liabilities and equity	$ 14,159	$ 13,424	[1]

[1] Reflects reclassifications to conform to current year presentation, which we discuss in Note 1.