SOUTHERN CALIFORNIA EDISON (SCE-PN) 10-K 22 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 20, 2018	Jun. 30, 2017
Entity Information [Line Items]
Entity Registrant Name	EDISON INTERNATIONAL
Entity Central Index Key	827,052
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		325,811,206
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 25,500,000,000
Southern California Edison Company
Entity Information [Line Items]
Entity Registrant Name	SOUTHERN CALIFORNIA EDISON CO
Entity Central Index Key	92,103
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		434,888,104
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total operating revenue	$ 12,320	$ 11,869	$ 11,524
Purchased power and fuel	4,873	4,527	4,266
Operation and maintenance	2,807	2,868	2,990
Depreciation and amortization	2,041	2,007	1,919
Property and other taxes	377	354	336
Impairment and other charges	738	21	5
Other operating income	(9)	0	0
Total operating expenses	10,827	9,777	9,516
Operating income	1,493	2,092	2,008
Interest and other income	146	123	174
Interest expense	(639)	(581)	(555)
Other expenses	(51)	(44)	(59)
Income from continuing operations before income taxes	949	1,590	1,568
Income tax expense	281	177	486
Income from continuing operations	668	1,413	1,082
Income from discontinued operations, net of tax	0	12	35
Net income	668	1,425	1,117
Preferred and preference stock dividend requirements of utility	124	123	113
Other noncontrolling interests	(21)	(9)	(16)
Net income from continuing operations available to common shareholders	565	1,311	1,020
Basic earnings per common share attributable to Edison International common shareholders:
Income from continuing operations, net of tax	565	1,299	985
Income from discontinued operations, net of tax	0	12	35
Net income from continuing operations available to common shareholders	$ 565	$ 1,311	$ 1,020
Basic earnings per common share attributable to Edison International common shareholders:
Weighted-average shares of common stock outstanding	326	326	326
Continuing operations (in dollars per share)	$ 1.73	$ 3.99	$ 3.02
Discontinued operations (in dollars per share)	0	0.03	0.11
Total (in dollars per share)	$ 1.73	$ 4.02	$ 3.13
Diluted earnings per common share attributable to Edison International common shareholders:
Weighted-average shares of common stock outstanding, including effect of dilutive securities	328	330	329
Continuing operations (in dollars per share)	$ 1.72	$ 3.94	$ 2.99
Discontinued operations (in dollars per share)	0	0.03	0.11
Total (in dollars per share)	1.72	3.97	3.10
Dividends declared per common share (in dollars per share)	$ 2.2325	$ 1.9825	$ 1.7325
Southern California Edison Company
Total operating revenue	$ 12,254	$ 11,830	$ 11,485
Purchased power and fuel	4,873	4,527	4,266
Operation and maintenance	2,671	2,737	2,890
Depreciation and amortization	2,032	1,998	1,915
Property and other taxes	372	351	334
Impairment and other charges	716	0	0
Other operating income	(8)	0	0
Total operating expenses	10,656	9,613	9,405
Operating income	1,598	2,217	2,080
Interest and other income	145	123	123
Interest expense	(589)	(541)	(526)
Other expenses	(48)	(44)	(59)
Income from continuing operations before income taxes	1,106	1,755	1,618
Income tax expense	(30)	256	507
Net income	1,136	1,499	1,111
Preferred and preference stock dividend requirements of utility	124	123	113
Net income from continuing operations available to common shareholders	1,012	1,376	998
Basic earnings per common share attributable to Edison International common shareholders:
Net income from continuing operations available to common shareholders	$ 1,012	$ 1,376	$ 998

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 668	$ 1,425	$ 1,117
Pension and postretirement benefits other than pensions:
Net gain or loss arising during the period plus amortization included in net income	10	2	1
Prior service cost arising during the period plus amortization included in net income	0	0	1
Other	0	1	0
Other comprehensive income, net of tax	10	3	2
Comprehensive income	678	1,428	1,119
Less: Comprehensive income attributable to noncontrolling interests	103	114	97
Comprehensive income	575	1,314	1,022
Southern California Edison Company
Net income	1,136	1,499	1,111
Pension and postretirement benefits other than pensions:
Net gain or loss arising during the period plus amortization included in net income	1	1	5
Prior service cost arising during the period plus amortization included in net income	0	0	1
Other	0	1	0
Other comprehensive income, net of tax	1	2	6
Comprehensive income	$ 1,137	$ 1,501	$ 1,117

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 1,091	$ 96
Receivables, less allowances for uncollectible accounts	717	714
Accrued unbilled revenue	212	370
Inventory	242	239
Income tax receivables	224	1
Prepaid expenses	233	103
Derivative assets	105	73
Regulatory assets	703	350
Other current assets	202	177
Total current assets	3,729	2,123
Nuclear decommissioning trusts	4,440	4,242
Other investments	73	83
Total investments	4,513	4,325
Utility property, plant and equipment, less accumulated depreciation and amortization	38,708	36,806
Nonutility property, plant and equipment, less accumulated depreciation	342	194
Total property, plant and equipment	39,050	37,000
Regulatory assets	4,914	7,455
Other long-term assets	374	416
Total long-term assets	5,288	7,871
Total assets	52,580	51,319
LIABILITIES AND EQUITY
Short-term debt	2,393	1,307
Current portion of long-term debt	481	981
Accounts payable	1,503	1,342
Accrued taxes	23	50
Customer deposits	281	269
Derivative liabilities	1	216
Regulatory liabilities	1,121	756
Other current liabilities	1,265	991
Total current liabilities	7,068	5,912
Long-term debt	11,642	10,175
Deferred income taxes and credits	4,567	8,327
Derivative liabilities	0	941
Pensions and benefits	943	1,354
Asset retirement obligations	2,908	2,590
Regulatory liabilities	8,614	5,726
Other deferred credits and other long-term liabilities	2,953	2,102
Total deferred credits and other liabilities	19,985	21,040
Total liabilities	38,695	37,127
Commitments and contingencies (Note 11)
Redeemable noncontrolling interest	19	5
Common stock, no par value	2,526	2,505
Accumulated other comprehensive loss	(43)	(53)
Retained earnings	9,188	9,544
Total common shareholder's equity	11,671	11,996
Noncontrolling interests – preferred and preference stock of utility	2,193	2,191
Other noncontrolling interests	2	0
Total equity	13,866	14,187
Total liabilities and equity	52,580	51,319
Southern California Edison Company
ASSETS
Cash and cash equivalents	515	39
Receivables, less allowances for uncollectible accounts	693	699
Accrued unbilled revenue	212	369
Inventory	242	239
Income tax receivables	229	16
Prepaid expenses	228	98
Derivative assets	105	73
Regulatory assets	703	350
Other current assets	160	148
Total current assets	3,087	2,031
Nuclear decommissioning trusts	4,440	4,242
Other investments	52	50
Total investments	4,492	4,292
Utility property, plant and equipment, less accumulated depreciation and amortization	38,708	36,806
Nonutility property, plant and equipment, less accumulated depreciation	77	75
Total property, plant and equipment	38,785	36,881
Regulatory assets	4,914	7,455
Other long-term assets	237	232
Total long-term assets	5,151	7,687
Total assets	51,515	50,891
LIABILITIES AND EQUITY
Short-term debt	1,238	769
Current portion of long-term debt	479	579
Accounts payable	1,519	1,344
Accrued taxes	24	45
Customer deposits	281	269
Derivative liabilities	1	216
Regulatory liabilities	1,121	756
Other current liabilities	1,224	729
Total current liabilities	5,887	4,707
Long-term debt	10,428	9,754
Deferred income taxes and credits	5,890	9,886
Derivative liabilities	0	941
Pensions and benefits	483	896
Asset retirement obligations	2,892	2,586
Regulatory liabilities	8,614	5,726
Other deferred credits and other long-term liabilities	2,649	1,912
Total deferred credits and other liabilities	20,528	21,947
Total liabilities	36,843	36,408
Commitments and contingencies (Note 11)
Common stock, no par value	2,168	2,168
Additional paid-in capital	671	657
Accumulated other comprehensive loss	(19)	(20)
Retained earnings	9,607	9,433
Total common shareholder's equity	12,427	12,238
Noncontrolling interests – preferred and preference stock of utility	2,245	2,245
Total equity	14,672	14,483
Total liabilities and equity	$ 51,515	$ 50,891

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Receivables, allowances for uncollectible accounts	$ 54	$ 62
Utility property, plant and equipment, accumulated depreciation	9,355	9,000
Nonutility property, plant and equipment, accumulated depreciation	$ 114	$ 99
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	325,811,206	325,811,206
Common stock, shares outstanding	325,811,206	325,811,206
Southern California Edison Company
Receivables, allowances for uncollectible accounts	$ 53	$ 61
Utility property, plant and equipment, accumulated depreciation	9,355	9,000
Nonutility property, plant and equipment, accumulated depreciation	$ 97	$ 89
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	560,000,000	560,000,000
Common stock, shares issued	434,888,104	434,888,104
Common stock, shares outstanding	434,888,104	434,888,104

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 668	$ 1,425	$ 1,117
Less: Income from discontinued operations	0	12	35
Income from continuing operations	668	1,413	1,082
Adjustments to reconcile to net cash provided by operating activities:
Depreciation and amortization	2,115	2,098	2,005
Allowance for equity during construction	(87)	(74)	(87)
Impairment and other charges	738	0	5
Deferred income taxes and investment tax credits	498	190	449
Other	22	20	(28)
Nuclear decommissioning trusts	(197)	(179)	(428)
EME settlement payments, net of insurance proceeds	0	(209)	(176)
Changes in operating assets and liabilities:
Receivables	7	52	49
Inventory	(12)	8	14
Accounts payable	50	35	8
Tax receivables and payables	(250)	(6)	(28)
Other current assets and liabilities	34	211	(24)
Derivative assets and liabilities, net	(28)	13	45
Regulatory assets and liabilities, net	4	(292)	1,729
Other noncurrent assets and liabilities	25	(24)	(106)
Net cash provided by operating activities	3,587	3,256	4,509
Cash flows from financing activities:
Long-term debt issued or remarketed, net of premium, discount and issuance costs	2,233	397	1,420
Long-term debt matured or repurchased	(1,285)	(220)	(762)
Preference stock issued, net	462	294	319
Preference stock redeemed	(475)	(125)	(325)
Short-term debt financing, net	1,084	611	(572)
Payments for stock-based compensation	(393)	(237)	(197)
Receipts from stock option exercises	215	135	128
Dividends and distribution to noncontrolling interests	(125)	(123)	(116)
Dividends paid	(707)	(626)	(544)
Other	(2)	(11)	61
Net cash provided by (used in) financing activities	1,007	95	(588)
Cash flows from investing activities:
Capital expenditures	(3,828)	(3,734)	(4,225)
Proceeds from sale of nuclear decommissioning trust investments	5,239	3,212	3,506
Purchases of nuclear decommissioning trust investments	(5,042)	(3,033)	(3,132)
Life insurance policy loans proceeds	26	140	0
Other	6	(1)	(41)
Net cash used in investing activities	(3,599)	(3,416)	(3,892)
Net increase (decrease) in cash and cash equivalents	995	(65)	29
Cash and cash equivalents, beginning of year	96	161	132
Cash and cash equivalents, end of year	1,091	96	161
Southern California Edison Company
Cash flows from operating activities:
Net income	1,136	1,499	1,111
Adjustments to reconcile to net cash provided by operating activities:
Depreciation and amortization	2,101	2,085	1,996
Allowance for equity during construction	(87)	(74)	(87)
Impairment and other charges	716	0	0
Deferred income taxes and investment tax credits	304	88	308
Other	12	9	14
Nuclear decommissioning trusts	(197)	(179)	(428)
Changes in operating assets and liabilities:
Receivables	6	25	25
Inventory	(11)	(3)	19
Accounts payable	50	45	30
Tax receivables and payables	(234)	(16)	(16)
Other current assets and liabilities	69	185	(42)
Derivative assets and liabilities, net	(28)	13	45
Regulatory assets and liabilities, net	4	(292)	1,729
Other noncurrent assets and liabilities	(116)	138	(80)
Net cash provided by operating activities	3,725	3,523	4,624
Cash flows from financing activities:
Long-term debt issued or remarketed, net of premium, discount and issuance costs	1,445	0	1,413
Long-term debt matured or repurchased	(882)	(217)	(761)
Preference stock issued, net	462	294	319
Preference stock redeemed	(475)	(125)	(325)
Short-term debt financing, net	469	719	(619)
Payments for stock-based compensation	(86)	(127)	(78)
Receipts from stock option exercises	48	76	68
Dividends paid	(697)	(824)	(874)
Other	(41)	(15)	45
Net cash provided by (used in) financing activities	243	(219)	(812)
Cash flows from investing activities:
Capital expenditures	(3,740)	(3,633)	(4,210)
Proceeds from sale of nuclear decommissioning trust investments	5,239	3,212	3,506
Purchases of nuclear decommissioning trust investments	(5,042)	(3,033)	(3,132)
Life insurance policy loans proceeds	26	140	0
Other	25	23	12
Net cash used in investing activities	(3,492)	(3,291)	(3,824)
Net increase (decrease) in cash and cash equivalents	476	13	(12)
Cash and cash equivalents, beginning of year	39	26	38
Cash and cash equivalents, end of year	$ 515	$ 39	$ 26

Consolidated Statements of Cas7

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Discounts and issuance costs of long term debt	$ 2	$ 7	$ 17
Southern California Edison Company
Discounts and issuance costs of long term debt	$ 10		$ (17)

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Southern California Edison Company	Common Stock	Common StockSouthern California Edison Company	Additional Paid-in CapitalSouthern California Edison Company	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive LossSouthern California Edison Company	Retained Earnings	Retained EarningsSouthern California Edison Company	Equity Attributable to Common Shareholders	Other	Preferred and Preference Stock	Preferred and Preference StockSouthern California Edison Company
Balance, at the beginning of the period at Dec. 31, 2014	$ 12,982	$ 13,282	$ 2,445	$ 2,168	$ 618	$ (58)	$ (28)	$ 8,573	$ 8,454	$ 10,960	$ 0	$ 2,022	$ 2,070
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,133	1,111						1,020	1,111	1,020		113
Other comprehensive income (loss)	2	6				2	6			2
Dividends declared on common stock	(564)	(611)						(564)	(611)	(564)
Dividends declared on preferred and preference stock		(113)							(113)
Dividends and distributions to noncontrolling interests and other	(113)											(113)
Stock-based compensation and other	(70)	(10)	15		23			(85)	(33)	(70)
Noncash stock-based compensation and other	24	13	24		13				0	24
Issuance of preference stock	319	319			(6)							319	325
Redemption of preference stock	(325)	(325)			4			(4)	(4)	(4)		(321)	(325)
Balance, at the end of the period at Dec. 31, 2015	13,388	13,672	2,484	2,168	652	(56)	(22)	8,940	8,804	11,368	0	2,020	2,070
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,434	1,499						1,311	1,499	1,311		123
Other comprehensive income (loss)	3	2				3	2			3
Dividends declared on common stock	(646)	(701)						(646)	(701)	(646)
Dividends declared on preferred and preference stock		(123)							(123)
Dividends and distributions to noncontrolling interests and other	(123)											(123)
Stock-based compensation and other	(60)	(44)	(1)					(59)	(44)	(60)
Noncash stock-based compensation and other	22	9	22		9					22
Issuance of preference stock	294	294			(6)							294	300
Redemption of preference stock	(125)	(125)			2			(2)	(2)	(2)		(123)	(125)
Balance, at the end of the period at Dec. 31, 2016	14,187	14,483	2,505	2,168	657	(53)	(20)	9,544	9,433	11,996	0	2,191	2,245
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	671	1,136						565	1,136	565	(18)	124
Other comprehensive income (loss)	10	1				10	1			10
Contribution from tax equity investor	20										20
Dividends declared on common stock	(727)	(785)						(727)	(785)	(727)
Dividends declared on preferred and preference stock		(124)							(124)
Dividends and distributions to noncontrolling interests and other	(124)											(124)
Stock-based compensation and other	(179)	(38)						(179)	(38)	(179)
Noncash stock-based compensation and other	21	12	21		12					21
Issuance of preference stock	462	462			(13)							462	475
Redemption of preference stock	(475)	(475)			15			(15)	(15)	(15)		(460)	(475)
Balance, at the end of the period at Dec. 31, 2017	$ 13,866	$ 14,672	$ 2,526	$ 2,168	$ 671	$ (43)	$ (19)	$ 9,188	$ 9,607	$ 11,671	$ 2	$ 2,193	$ 2,245

Consolidated Statements of Cha9

Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares	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
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.6050	$ 0.5425	$ 0.5425	$ 0.5425	$ 0.5425	$ 0.4800	$ 0.4800	$ 0.4800	$ 2.2325	$ 1.9825	$ 1.7325

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Organization and Basis of Presentation Edison International is the parent holding company of Southern California Edison Company ("SCE") and Edison Energy Group, Inc. ("Edison Energy Group"). SCE is an investor-owned public utility primarily engaged in the business of supplying and delivering electricity to an approximately 50,000 square mile area of southern California. Edison Energy Group is a holding company for subsidiaries, including Edison Energy, LLC ("Edison Energy") and SoCore Energy LLC ("SoCore Energy"), engaged in pursuing competitive business opportunities across energy services, managed portfolio solutions, and distributed solar solutions for commercial and industrial customers. Such business activities are currently not material to report as a separate business segment. These combined notes to the consolidated financial statements apply to both Edison International and SCE unless otherwise described. Edison International's consolidated financial statements include the accounts of Edison International, SCE and other wholly owned and controlled subsidiaries. References to Edison International refer to the consolidated group of Edison International and its subsidiaries. References to Edison International Parent and Other refer to Edison International Parent and its competitive subsidiaries. SCE's consolidated financial statements include the accounts of SCE and its wholly owned and controlled subsidiaries. All intercompany transactions have been eliminated from the consolidated financial statements. Edison International's and SCE's accounting policies conform to accounting principles generally accepted in the United States of America, including the accounting principles for rate-regulated enterprises, which reflect the ratemaking policies of the California Public Utility Commission ("CPUC") and the Federal Energy Regulatory Commission ("FERC"). SCE applies authoritative guidance for rate-regulated enterprises to the portion of its operations in which regulators set rates at levels intended to recover the estimated costs of providing service, plus a return on net investments in assets, or rate base. Regulators may also impose certain penalties or grant certain incentives. Due to timing and other differences in the collection of electric utility revenue, these principles require an incurred cost that would otherwise be charged to expense by a non-regulated entity to be capitalized as a regulatory asset if it is probable that the cost is recoverable through future rates; and conversely the principles require recording of a regulatory liability for amounts collected in rates to recover costs expected to be incurred in the future or amounts collected in excess of costs incurred and refundable to customers. In addition, SCE recognizes revenue and regulatory assets from alternative revenue programs, which enables the utility to adjust future rates in response to past activities or completed events, if certain criteria are met, even for programs that do not qualify for recognition of "traditional" regulatory assets and liabilities. SCE assesses, at the end of each reporting period, whether regulatory assets are probable of future recovery. See Note 10 for composition of regulatory assets and liabilities. The preparation of financial statements in conformity with United States generally accepted accounting principles ("GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reported period. Actual results could differ from those estimates. Cash Equivalents Cash equivalents includes investments in money market funds. Generally, the carrying value of cash equivalents equals the fair value, as these investments have original maturities of three months or less. The cash equivalents were as follows: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Money market funds $ 1,024 $ 41 $ 483 $ 18 Cash is temporarily invested until required for check clearing. Checks issued, but not yet paid by the financial institution, are reclassified from cash to accounts payable at the end of each reporting period as follows: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Book balances reclassified to accounts payable $ 64 $ 138 $ 63 $ 136 Restricted Cash Edison International's restricted cash at December 31, 2017 and 2016 were $41 million and $18 million , respectively. Restricted cash primarily relates to funds held by SoCore Energy and its consolidated affiliates pursuant to project financing or purchase agreements; most of which are expected to lapse by the end of 2018 . Allowance for Uncollectible Accounts Allowances for uncollectible accounts are provided based upon a variety of factors, including historical amounts written-off, current economic conditions and assessment of customer collectability. Inventory SCE's inventory is primarily composed of materials, supplies and spare parts, and generally stated at average cost. Emission Allowances SCE is allocated greenhouse gas ("GHG") allowances annually which it is then required to sell into quarterly auctions. GHG proceeds from the auctions are recorded as a regulatory liability to be refunded to customers. SCE purchases GHG allowances in quarterly auctions or from counterparties to satisfy its GHG emission compliance obligations and recovers such costs of GHG allowances from customers. GHG allowances held for use are classified as "Other current assets" on the consolidated balance sheets and are stated, similar to an inventory method, at the lower of weighted-average cost or market. SCE had GHG allowances of $127 million and $113 million at December 31, 2017 and 2016 , respectively. GHG emission obligations were $129 million and $95 million at December 31, 2017 and 2016 , respectively, and are classified as "Other current liabilities" on the consolidated balance sheets. Property, Plant and Equipment SCE plant additions, including replacements and betterments, are capitalized. Direct material and labor and indirect costs such as construction overhead, administrative and general costs, pension and benefits, and property taxes are capitalized as part of plant additions. The CPUC authorizes a capitalization rate for each of the indirect costs which are allocated to each project based on either labor or total costs. Estimated useful lives (authorized by the CPUC) and weighted-average useful lives of SCE's property, plant and equipment, are as follows: Estimated Useful Lives Weighted-Average Useful Lives Generation plant 10 years to 55 years 37 years Distribution plant 20 years to 60 years 43 years Transmission plant 40 years to 65 years 52 years General plant and other 5 years to 60 years 22 years Depreciation of utility property, plant and equipment is computed on a straight-line, remaining-life basis. Depreciation expense was $1.61 billion , $1.52 billion and $1.42 billion for 2017 , 2016 and 2015 , respectively. Depreciation expense stated as a percent of average original cost of depreciable utility plant was, on a composite basis, 3.8% , 3.8% and 3.9% for 2017 , 2016 and 2015 , respectively. The original costs of retired property is charged to accumulated depreciation. Nuclear fuel for the Palo Verde Nuclear Generating Station ("Palo Verde") is recorded as utility plant (nuclear fuel in the fabrication and installation phase is recorded as construction in progress) in accordance with CPUC ratemaking procedures. Palo Verde nuclear fuel is amortized using the units of production method. Allowance for funds used during construction ("AFUDC") represents the estimated cost of debt and equity funds that finance utility-plant construction and is capitalized during certain plant construction. AFUDC is recovered in rates through depreciation expense over the useful life of the related asset. AFUDC equity represents a method to compensate SCE for the estimated cost of equity used to finance utility plant additions and is recorded as part of construction in progress. AFUDC equity was $87 million , $74 million and $87 million in 2017 , 2016 and 2015 , respectively, and is reflected in "Interest and other income." AFUDC debt was $28 million , $23 million and $31 million in 2017 , 2016 and 2015 , respectively and is reflected as a reduction of "Interest expense." Major Maintenance Major maintenance costs for SCE's power plant facilities and equipment are expensed as incurred. Impairment of Long-Lived Assets Impairments of long-lived assets are evaluated based on a review of estimated future cash flows expected to be generated whenever events or changes in circumstances indicate that the carrying amount of such investments or assets may not be recoverable. If the carrying amount of a long-lived asset exceeds expected future cash flows, undiscounted and without interest charges, an impairment loss is recognized in the amount of the excess of fair value over the carrying amount. Fair value is determined via market, cost and income based valuation techniques, as appropriate. Goodwill Edison International assesses goodwill through annual goodwill impairment tests, at the reporting unit level as of October 1st of each year. Edison International will update these tests between annual tests if events occur or circumstances change such that it is more likely than not that the fair value of a reporting unit is below its carrying value. During 2017, Edison International completed a strategic review of Edison Energy Group's competitive businesses. Edison International has concluded that it will evaluate strategic options, including potential sale opportunities, for SoCore Energy. In connection with the strategic review of the Edison Energy Group's competitive businesses, Edison International evaluated the recoverability of goodwill and recorded an impairment of SoCore Energy's goodwill totaling $16.5 million ( $10 million after-tax) in the second quarter of 2017. The fair value of the Edison Energy and SoCore Energy reporting units exceeded their carrying values at the date of the impairment analysis. As of December 31, 2017 and 2016, goodwill is comprised of $78 million at each year end at the Edison Energy reporting unit and $5 million and $22 million , respectively, at the SoCore Energy reporting unit. Nuclear Decommissioning and Asset Retirement Obligations The fair value of a liability for an asset retirement obligation ("ARO") is recorded in the period in which it is incurred, including a liability for the fair value of a conditional ARO, if the fair value can be reasonably estimated even though uncertainty exists about the timing and/or method of settlement. When an ARO liability is initially recorded, SCE capitalizes the cost by increasing the carrying amount of the related long-lived asset. For each subsequent period, the liability is increased for accretion expense and the capitalized cost is depreciated over the useful life of the related asset. AROs related to decommissioning of SCE's nuclear power facilities are based on site-specific studies conducted as part of each Nuclear Decommissioning Cost Triennial Proceeding ("NDCTP") conducted before the CPUC. Revisions of an ARO are established for updated site-specific decommissioning cost estimates. SCE adjusts its nuclear decommissioning obligation into a nuclear-related ARO regulatory asset and also records an ARO regulatory liability as a result of timing differences between the recognition of costs and the recovery of costs through the ratemaking process. For further information, see Notes 9 and 10. SCE has not recorded an asset retirement obligation for assets that are expected to operate indefinitely or where SCE cannot estimate a settlement date (or range of potential settlement dates). As such, ARO liabilities are not recorded for certain retirement activities, including certain hydroelectric facilities. The following table summarizes the changes in SCE's ARO liability, including San Onofre Nuclear Generating Station ("San Onofre") and Palo Verde: December 31, (in millions) 2017 2016 Beginning balance $ 2,586 $ 2,762 Accretion 1 166 157 Revisions 376 (165 ) Liabilities settled (236 ) (168 ) Ending balance $ 2,892 $ 2,586 1 An ARO represents the present value of a future obligation. Accretion is an increase in the liability to account for the time value of money resulting from discounting. The recorded liability to decommission SCE's nuclear power facilities (included in the table above) is $2.6 billion as of December 31, 2017. In 2016, SCE updated the recorded liability for Palo Verde and San Onofre Unit 1 based on the 2013 decommissioning study performed for Palo Verde and the 2014 study for San Onofre Unit 1. In 2017, SCE further revised the recorded liability for Palo Verde and San Onofre Units 2 and 3 based on updated cost estimates, including changes related to onboarding the general contractor. The final site specific study for San Onofre Units 2 and 3 is expected to be filed in March 2018 as part of the 2018 NDCTP which may result in additional changes to the ARO estimate. Decommissioning costs, which are recovered through customer rates over the term of each nuclear facility's operating license, are recorded as a component of depreciation expense, with a corresponding credit to the ARO regulatory liability. Amortization of the ARO asset (included within the unamortized nuclear investment) and accretion of the ARO liability are deferred as increases to the ARO regulatory liability account, resulting in no impact on earnings. SCE has collected in rates amounts for the future decommissioning of its nuclear assets, and has placed those amounts in independent trusts. Amounts collected in rates in excess of the ARO liability are classified as regulatory liabilities. Changes in the estimated costs, timing of decommissioning or the assumptions underlying these estimates could cause material revisions to the estimated total cost to decommission. SCE currently estimates that it will spend approximately $7.2 billion through 2079 to decommission its nuclear facilities. This estimate is based on SCE's decommissioning cost methodology used for ratemaking purposes, escalated at rates ranging from 1.6% to 7.5% (depending on the cost element) annually. These costs are expected to be funded from independent decommissioning trusts. SCE estimates annual after-tax earnings on the decommissioning funds of 2.4% to 3.8% . Future decommissioning costs related to SCE's nuclear assets are expected to be funded from independent decommissioning trusts. If the assumed return on trust assets is not earned or costs escalate at higher rates, SCE expects that additional funds needed for decommissioning will be recoverable through future rates. See Note 9 for further information. Due to regulatory recovery of SCE's nuclear decommissioning expense, prudently incurred costs for nuclear decommissioning activities do not affect SCE's earnings. SCE's nuclear decommissioning costs are subject to CPUC review through the triennial regulatory proceeding. SCE's nuclear decommissioning trust investments primarily consist of fixed income and equity investments that are classified as available-for-sale. Due to regulatory mechanisms, earnings and realized gains and losses (including other-than-temporary impairments) have no impact on earnings. Unrealized gains and losses on decommissioning trust funds increase or decrease the trust assets and the related regulatory asset or liability and have no impact on electric utility revenue or decommissioning expense. SCE reviews each security for other-than-temporary impairment on the last day of each month. If the fair value on the last day of two consecutive months is less than the cost for that security, SCE recognizes a loss for the other-than-temporary impairment. If the fair value is greater or less than the carrying value for that security at the time of sale, SCE recognizes a related realized gain or loss, respectively. Deferred Financing Costs Debt premium, discount and issuance expenses incurred in connection with obtaining financing are deferred and amortized on a straight-line basis. Under CPUC ratemaking procedures, SCE's debt reacquisition expenses are amortized over the remaining life of the reacquired debt or, if refinanced, the life of the new debt. SCE had unamortized losses on reacquired debt of $168 million and $184 million at December 31, 2017 and 2016 , respectively, reflected as long-term "Regulatory assets" in the consolidated balance sheets. Edison International and SCE had unamortized debt issuance costs related to issuances under the credit facilities of $15 million and $7 million at December 31, 2017 , respectively, and $10 million and $7 million at December 31, 2016 , respectively, reflected in "Other long-term assets" on the consolidated balance sheets. In addition, Edison International and SCE had debt issuance costs related to issuances of long-term debt of $88 million and $77 million at December 31, 2017 , respectively, and $81 million and $71 million at December 31, 2016 , respectively, reflected as a reduction of "Long-term debt" on the consolidated balance sheets. Amortization of deferred financing costs charged to interest expense is as follows: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Amortization of deferred financing costs charged to interest expense $ 30 $ 31 $ 33 $ 27 $ 27 $ 28 Revenue Recognition Revenue is recognized when electricity is delivered and includes amounts for services rendered but unbilled at the end of each reporting period as reflected in "Operating revenue" on the consolidated statements of income. Rates charged to customers are based on CPUC- and FERC-authorized revenue requirements. CPUC rates are implemented subsequent to final approval. CPUC rates decouple authorized revenue from the volume of electricity sales. Differences between amounts collected and authorized levels are either collected from or refunded to customers, and therefore, SCE earns revenue equal to amounts authorized. FERC rates also decouple revenue from volume of electricity sales. In November 2013, the FERC approved a formula rate effective January 1, 2012 to determine SCE's FERC transmission revenue requirement, including its construction work in progress ("CWIP") revenue requirement. Under operation of the formula rate, transmission revenue will be updated to actual cost of service annually. Differences between amounts collected and determined under the formula rate are either collected from or refunded to customers, and therefore, SCE earns revenue based on estimates of recorded rate base costs under the FERC formula rate. SCE bills certain sales and use taxes levied by state or local governments to its customers. Included in these sales and use taxes are franchise fees, which SCE pays to various municipalities (based on contracts with these municipalities) in order to operate within the limits of the municipality. SCE bills these franchise fees to its customers based on a CPUC-authorized rate. These franchise fees, which are required to be paid regardless of SCE's ability to collect from the customer, are accounted for on a gross basis and reflected in electric utility revenue and other operation and maintenance expense. SCE's franchise fees billed to customers and recorded as revenue were $133 million , $111 million and $138 million in 2017 , 2016 and 2015 , respectively. When SCE acts as an agent, the taxes are accounted for on a net basis. Amounts billed to and collected from customers for these taxes are remitted to the taxing authorities and are not recognized as electric utility revenue. Power Purchase Agreements SCE enters into power purchase agreements in the normal course of business. A power purchase agreement may be considered a variable interest in a variable interest entity ("VIE"). If SCE is the primary beneficiary in the VIE, SCE should consolidate the VIE. None of SCE's power purchase agreements resulted in consolidation of a VIE at December 31, 2017 and 2016 . See Note 3 for further discussion of power purchase agreements that are considered variable interests. A power purchase agreement may also contain a lease for accounting purposes. This generally occurs when a power purchase agreement designates a specific power plant in which the buyer purchases substantially all of the output and does not otherwise meet a fixed price per unit of output exception. SCE has a number of power purchase agreements that contain leases. SCE's recognition of lease expense conforms to the ratemaking treatment for SCE's recovery of the cost of electricity and is recorded in "Purchased power and fuel" on the consolidated statements of income. See Note 11 for further discussion of SCE's power purchase agreements, including agreements that are classified as operating and capital leases for accounting purposes. A power purchase agreement that does not contain a lease may be classified as a derivative which is recorded at fair value on the consolidated balance sheets. These power purchase agreements may be eligible for an election to designate as a normal purchase and sale, which is accounted for on an accrual basis as an executory contract. See Note 6 for further information on derivative instruments. Power purchase agreements that do not meet the above classifications are accounted for on an accrual basis. Derivative Instruments SCE records derivative instruments on its consolidated balance sheets as either assets or liabilities measured at fair value unless otherwise exempted from derivative treatment as normal purchases or sales. The normal purchases and sales exception requires, among other things, physical delivery in quantities expected to be used or sold over a reasonable period in the normal course of business. During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms. Realized gains and losses from SCE's derivative instruments are expected to be recovered from or refunded to customers through regulatory mechanisms and, therefore, SCE's fair value changes have no impact on purchased-power expense or earnings. SCE does not use hedge accounting for derivative transactions due to regulatory accounting treatment. Where SCE's derivative instruments are subject to a master netting agreement and certain criteria are met, SCE presents its derivative assets and liabilities on a net basis on its consolidated balance sheets. In addition, derivative positions are offset against margin and cash collateral deposits. The results of derivative activities are recorded as part of cash flows from operating activities on the consolidated statements of cash flows. See Note 6 for further information on derivative instruments. Leases SCE enters into power purchase agreements that may contain leases, as discussed under "Power Purchase Agreements" above. SCE also enters into a number of agreements to lease property and equipment in the normal course of business. Minimum lease payments under SCE's operating leases for property and equipment are reflected in "Operation and maintenance" on the consolidated statements of income. Stock-Based Compensation Stock options, performance shares, deferred stock units and restricted stock units have been granted under Edison International's long-term incentive compensation programs. Generally, Edison International does not issue new common stock for settlement of equity awards, which are recorded as part of retained earnings. Rather, a third party is used to purchase shares from the market and deliver such shares for the settlement of option exercises, performance shares, deferred stock units and restricted stock units. The performance shares awarded that are earned are settled solely in cash. Deferred stock units and restricted stock units are settled in common stock; however, Edison International will substitute cash awards to the extent necessary to pay tax withholding or any government levies. Stock-based compensation expense is recognized on a straight-line basis over the requisite service period and is based on the number of awards that are expected to vest. Edison International and SCE estimate the number of awards that are expected to vest rather than account for forfeitures when they occur. For awards granted to retirement-eligible participants, stock compensation expenses are recognized on a prorated basis over the initial year. For awards granted to participants who become eligible for retirement during the requisite service period, stock compensation expenses are recognized over the period between the date of grant and the date the participant first becomes eligible for retirement. Under new accounting guidance adopted in 2016, share-based payments may create a permanent difference between the amount of compensation expense recognized for book and tax purposes. The tax impact of this permanent difference is recognized in earnings in the period it is created. Effective January 1, 2016, the excess tax benefits are classified as an operating activity along with other income tax cash flows on the statement of cash flows. SCE Dividend Restrictions The CPUC regulates SCE's capital structure which limits the dividends it may pay Edison International. Under CPUC regulations, SCE may make distributions to Edison International as long as the common equity component of SCE's capital structure remains at or above 48% on a 13 -month average basis, or otherwise satisfies the CPUC requirements. If the Revised San Onofre Settlement Agreement is approved by the CPUC, SCE may exclude the $448 million after-tax charge resulting from the implementation of the Revised San Onofre Settlement Agreement from its ratemaking capital structure. See Note 11 for discussion of the Revised San Onofre Settlement Agreement. At December 31, 2017 , without excluding the $448 million after-tax charge, SCE's 13 -month average common equity component of total capitalization was 50.0% and the maximum additional dividend that SCE could pay to Edison International under this limitation was approximately $511 million , resulting in a restriction on net assets of approximately $14.2 billion . If the Revised San Onofre Settlement Agreement had been approved by the CPUC at December 31, 2017, the common equity component of SCE's capital structure would have been 50.1% on a 13 -month average basis. Earnings Per Share Edison International computes earnings per common share ("EPS") using the two-class method, which is an earnings allocation formula that determines EPS for each class of common stock and participating security. Edison International's participating securities are stock-based compensation awards payable in common shares, including performance shares and restricted stock units, which earn dividend equivalents on an equal basis with common shares once the awards are vested. Performance shares awarded prior to 2015 that are earned are settled half in common shares and half in cash, while the performance shares awarded on or after 2015 that are earned are settled solely in cash. For further information, see Note 8. EPS attributable to Edison International common shareholders was computed as follows: Years ended December 31, (in millions, except per-share amounts) 2017 2016 2015 Basic earnings per share – continuing operations: Income from continuing operations attributable to common shareholders $ 565 $ 1,299 $ 985 Participating securities dividends — — (1 ) Income from continuing operations available to common shareholders $ 565 $ 1,299 $ 984 Weighted average common shares outstanding 326 326 326 Basic earnings per share – continuing operations $ 1.73 $ 3.99 $ 3.02 Diluted earnings per share – continuing operations: Income from continuing operations attributable to common shareholders $ 565 $ 1,299 $ 985 Participating securities dividends — — (1 ) Income from continuing operations available to common shareholders $ 565 $ 1,299 $ 984 Income impact of assumed conversions — 1 1 Income from continuing operations available to common shareholders and assumed conversions $ 565 $ 1,300 $ 985 Weighted average common shares outstanding 326 326 326 Incremental shares from assumed conversions 2 4 3 Adjusted weighted average shares – diluted 328 330 329 Diluted earnings per share – continuing operations $ 1.72 $ 3.94 $ 2.99 In addition to the participating securities discussed above, Edison International also may award stock options which are payable in common shares and are included in the diluted earnings per share calculation. Stock option awards to purchase 1,334,451 , 167,795 and 2,046,045 shares of common stock for the years ended December 31, 2017 , 2016 and 2015 , respectively, were outstanding, but were not included in the computation of diluted earnings per share because the effect would have been antidilutive. Income Taxes Edison International and SCE estimate their income taxes for each jurisdiction in which they operate. This involves estimating current period tax expense along with assessing temporary differences resulting from differing treatment of items (such as depreciation) for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included in the consolidated balance sheets. In December 2017, the Tax Cuts and Jobs Act ("Tax Reform") was signed into law. This comprehensive reform of tax law reduces the federal corporate income tax rate from 35% to 21% which resulted in the re-measurement of deferred taxes using the new tax rate. See Note 7 for further information. Income tax expense includes the current tax liability from operations and the change in deferred income taxes during the year. Investment tax credits are deferred and amortized to income tax expense over the lives of the properties or the term of the power purchase agreement of the respective project. Interest income, interest expense and penalties associated with income taxes are reflected in "Income tax expense" on the consolidated statements of income. Edison International's eligible subsidiaries are included in Edison International's consolidated federal income tax and combined state tax returns. Edison International has tax-allocation and payment agreements with certain of its subsidiaries. Pursuant to an income tax-allocation agreement approved by the CPUC, SCE's tax liability is computed as if it filed its federal and state income tax returns on a separate return basis. Noncontrolling Interest Noncontrolling interest represents the portion of equity ownership in an entity that is not attributable to the equity holders of Edison International. Noncontrolling interests held by third parties that have rights to put their ownership back to a subsidiary of Edison International are classified outside shareholders' equity as redeemable noncontrolling interest. Noncontrolling interest is initially recorded at fair value and is subsequently adjusted for income allocated to the noncontrolling interest and any distributions paid to the noncontrolling interest. Certain solar projects for commercial customers are organized as limited liability companies and have noncontrolling equity investors (referred to as tax equity investors) which are entitled to allocations of earnings, tax attributes and cash flows in accordance with contractual agreements that vary over time. These entities are consolidated for financial reporting purposes but are not subject to income taxes as the taxable income (loss) and investment tax credits are allocated to the respective owners. The total consolidated assets and liabilities of these entities were $299 million and $41 million , respectively, at December 31, 2017 and $74 million and $23 million , respectively, at December 31, 2016. Income (loss) of these entities is allocated to the noncontrolling interest based on the hypothetical liquidation at book value ("HLBV") accounting method. The HLBV accounting method is an approach that calculates the change in the claims of each member on the net assets of the investment at the beginning and end of each period. Each member's claim is equal to the amount each party would receive or pay if the net assets of the investment were to liquidate at book value. Under the contra

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment SCE's property, plant and equipment included in the consolidated balance sheets is composed of the following: December 31, (in millions) 2017 2016 Distribution $ 23,633 $ 22,332 Transmission 13,127 12,549 Generation 3,468 3,376 General plant and other 4,534 4,633 Accumulated depreciation (9,355 ) (9,000 ) 35,407 33,890 Construction work in progress 3,175 2,790 Nuclear fuel, at amortized cost 126 126 Total utility property, plant and equipment $ 38,708 $ 36,806 Capitalized Software Costs SCE capitalizes costs incurred during the application development stage of internal use software projects to property, plant, and equipment. SCE amortizes capitalized software costs ratably over the expected lives of the software, primarily ranging from 5 to 10 years and commencing upon operational use. Capitalized software costs, included in general plant and other above, were $1.1 billion and $1.4 billion at December 31, 2017 and 2016, respectively, and accumulated amortization was $0.6 billion and $0.8 billion , at December 31, 2017 and 2016 , respectively. Amortization expense for capitalized software was $233 million , $249 million and $268 million in 2017 , 2016 and 2015 , respectively. At December 31, 2017 , amortization expense is estimated to be $176 million , $127 million , $92 million , $62 million and $26 million for 2018 through 2022 , respectively. Jointly Owned Utility Projects SCE owns undivided interests in several generating assets for which each participant provides its own financing. SCE's proportionate share of these assets is reflected in the consolidated balance sheets and included in the above table. SCE's proportionate share of expenses for each project is reflected in the consolidated statements of income. A portion of the investments in Palo Verde generating stations is included in regulatory assets on the consolidated balance sheets. For further information, see Note 10. The following is SCE's investment in each asset as of December 31, 2017 : (in millions) Plant in Service Construction Work in Progress Accumulated Depreciation Nuclear Fuel (at amortized cost) Net Book Value Ownership Interest Transmission systems: Eldorado $ 237 $ 14 $ 24 $ — $ 227 59 % Pacific Intertie 192 41 78 — 155 50 % Generating station: Palo Verde (nuclear) 2,001 52 1,557 126 622 16 % Total $ 2,430 $ 107 $ 1,659 $ 126 $ 1,004 In addition, SCE has ownership interests in jointly owned power poles with other companies.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2017
Variable Interest Entities Disclosure [Abstract]
Variable Interest Entities	Variable Interest Entities A VIE is defined as a legal entity that meets one of two conditions: (1) the equity owners do not have sufficient equity at risk, or (2) the holders of the equity investment at risk, as a group, lack any of the following three characteristics: decision-making rights, the obligation to absorb losses, or the right to receive the expected residual returns of the entity. The primary beneficiary is identified as the variable interest holder that has both the power to direct the activities of the VIE that most significantly impact the entity's economic performance and the obligation to absorb losses or the right to receive benefits from the entity that could potentially be significant to the VIE. The primary beneficiary is required to consolidate the VIE. A subsidiary of Edison International is the primary beneficiary of entities that own solar projects (for further information, see Note 1—Noncontrolling Interests). Commercial and operating activities are generally the factors that most significantly impact the economic performance of such VIEs. Commercial and operating activities include site and equipment selection, construction, operation and maintenance, fuel procurement, dispatch and compliance with regulatory and contractual requirements. Variable Interest in VIEs that are not Consolidated Power Purchase Agreements SCE has power purchase agreements ("PPAs") that are classified as variable interests in VIEs, including tolling agreements through which SCE provides the natural gas to fuel the plants and contracts with qualifying facilities ("QFs") that contain variable pricing provisions based on the price of natural gas. SCE has concluded that it is not the primary beneficiary of these VIEs since it does not control the commercial and operating activities of these entities. Since payments for capacity are the primary source of income, the most significant economic activity for these VIEs is the operation and maintenance of the power plants. As of the balance sheet date, the carrying amount of assets and liabilities in SCE's consolidated balance sheet that relate to its involvement with VIEs result from amounts due under the PPAs. Under these contracts, SCE recovers the costs incurred through demonstration of compliance with its California Public Utilities Commission ("CPUC")-approved long-term power procurement plans. SCE has no residual interest in the entities and has not provided or guaranteed any debt or equity support, liquidity arrangements, performance guarantees or other commitments associated with these contracts other than the purchase commitments described in Note 11. As a result, there is no significant potential exposure to loss to SCE from its variable interest in these VIEs. The aggregate contracted capacity dedicated to SCE from these VIE projects was 4,898 megawatts ("MW") and 4,353 MW at December 31, 2017 and 2016 , respectively, and the amounts that SCE paid to these projects were $767 million and $788 million for the years ended December 31, 2017 and 2016 , respectively. These amounts are recoverable in customer rates, subject to reasonableness review. Unconsolidated Trusts of SCE SCE Trust I, Trust II, Trust III, Trust IV, Trust V and Trust VI were formed in 2012, 2013, 2014, 2015, 2016 and 2017, respectively, for the exclusive purpose of issuing the 5.625% , 5.10% , 5.75% , 5.375% , 5.45% and 5.00% trust preference securities, respectively ("trust securities"). The trusts are VIEs. SCE has concluded that it is not the primary beneficiary of these VIEs as it does not have the obligation to absorb the expected losses or the right to receive the expected residual returns of the trusts. SCE Trust I, Trust II, Trust III, Trust IV, Trust V and Trust VI issued to the public trust securities in the face amounts of $475 million , $400 million , $275 million , $325 million , $ 300 million , and $475 million (cumulative, liquidation amounts of $25 per share), respectively, and $10,000 of common stock each to SCE. The trusts invested the proceeds of these trust securities in Series F, Series G, Series H, Series J, Series K and Series L Preference Stock issued by SCE in the principal amounts of $475 million , $400 million , $275 million , $325 million , $ 300 million , and $475 million (cumulative, $2,500 per share liquidation values), respectively, which have substantially the same payment terms as the respective trust securities. The Series F, Series G, Series H, Series J, Series K, and Series L Preference Stock and the corresponding trust securities do not have a maturity date. Upon any redemption of any shares of the Series F, Series G, Series H, Series J, Series K or Series L Preference Stock, a corresponding dollar amount of trust securities will be redeemed by the applicable trust (see Note 12 for further information). The applicable trust will make distributions at the same rate and on the same dates on the applicable series of trust securities if and when the SCE board of directors declares and makes dividend payments on the related Preference Stock. The applicable trust will use any dividends it receives on the related Preference Stock to make its corresponding distributions on the applicable series of trust securities. If SCE does not make a dividend payment to any of these trusts, SCE would be prohibited from paying dividends on its common stock. SCE has fully and unconditionally guaranteed the payment of the trust securities and trust distributions, if and when SCE pays dividends on the related Preference Stock. In July 2017, SCE Trust I redeemed $ 475 million of trust securities from the public and $10,000 of common stock from SCE. As a result in September 2017, SCE Trust I was terminated. The Trust II, Trust III, Trust IV, and Trust V balance sheets as of December 31, 2017 and 2016 , consisted of investments of $400 million , $275 million , $325 million , and $300 million in the Series G, Series H, Series J, and Series K Preference Stock, respectively, $400 million , $275 million , $325 million , and $300 million of trust securities, respectively, and $10,000 each of common stock. The Trust VI balance sheet as of December 31, 2017 consisted of investments of $475 million in the Series L Preference Stock, $475 million of trust securities, and $10,000 of common stock. The following table provides a summary of the trusts' income statements: Years ended December 31, (in millions) Trust I Trust II Trust III Trust IV Trust V Trust VI 2017 Dividend income $ 14 $ 20 $ 16 $ 17 $ 16 $ 12 Dividend distributions 14 20 16 17 16 12 2016 Dividend income $ 27 $ 20 $ 16 $ 17 $ 13 * Dividend distributions 27 20 16 17 13 * 2015 Dividend income $ 27 $ 20 $ 16 $ 6 * * Dividend distributions 27 20 16 6 * * * Not applicable

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Recurring Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (referred to as an "exit price"). Fair value of an asset or liability considers assumptions that market participants would use in pricing the asset or liability, including assumptions about nonperformance risk. As of December 31, 2017 and 2016 , nonperformance risk was not material for Edison International and SCE. Assets and liabilities are categorized into a three-level fair value hierarchy based on valuation inputs used to determine fair value. Level 1 – The fair value of Edison International's and SCE's Level 1 assets and liabilities is determined using unadjusted quoted prices in active markets that are available at the measurement date for identical assets and liabilities. This level includes exchange-traded equity securities, U.S. treasury securities, mutual funds and money market funds. Level 2 – Edison International's and SCE's Level 2 assets and liabilities include fixed income securities, primarily consisting of U.S. government and agency bonds, municipal bonds and corporate bonds, and over-the-counter derivatives. The fair value of fixed income securities is determined using a market approach by obtaining quoted prices for similar assets and liabilities in active markets and inputs that are observable, either directly or indirectly, for substantially the full term of the instrument. The fair value of SCE's over-the-counter derivative contracts is determined using an income approach. SCE uses standard pricing models to determine the net present value of estimated future cash flows. Inputs to the pricing models include forward published or posted clearing prices from exchanges (New York Mercantile Exchange and Intercontinental Exchange) for similar instruments and discount rates. A primary price source that best represents trade activity for each market is used to develop observable forward market prices in determining the fair value of these positions. Broker quotes, prices from exchanges or comparison to executed trades are used to validate and corroborate the primary price source. These price quotations reflect mid-market prices (average of bid and ask) and are obtained from sources believed to provide the most liquid market for the commodity. Level 3 – The fair value of SCE's Level 3 assets and liabilities is determined using the income approach through various models and techniques that require significant unobservable inputs. This level includes derivative contracts that trade infrequently such as congestion revenue rights ("CRRs"). Edison International Parent and Other does not have any Level 3 assets and liabilities. Assumptions are made in order to value derivative contracts in which observable inputs are not available. In circumstances where fair value cannot be verified with observable market transactions, it is possible that a different valuation model could produce a materially different estimate of fair value. Modeling methodologies, inputs and techniques are reviewed and assessed as markets continue to develop and more pricing information becomes available and the fair value is adjusted when it is concluded that a change in inputs or techniques would result in a new valuation that better reflects the fair value of those derivative contracts. See Note 6 for a discussion of derivative instruments. SCE The following table sets forth assets and liabilities of SCE that were accounted for at fair value by level within the fair value hierarchy: December 31, 2017 (in millions) Level 1 Level 2 Level 3 Netting and Collateral 1 Total Assets at fair value Derivative contracts $ — $ 9 $ 102 $ (1 ) $ 110 Money market funds and other 495 — — — 495 Nuclear decommissioning trusts: Stocks 2 1,596 — — — 1,596 Fixed Income 3 1,065 1,665 — — 2,730 Short-term investments, primarily cash equivalents 101 72 — — 173 Subtotal of nuclear decommissioning trusts 4 2,762 1,737 — — 4,499 Total assets 3,257 1,746 102 (1 ) 5,104 Liabilities at fair value Derivative contracts — 2 1 (2 ) 1 Total liabilities — 2 1 (2 ) 1 Net assets $ 3,257 $ 1,744 $ 101 $ 1 $ 5,103 December 31, 2016 (in millions) Level 1 Level 2 Level 3 Netting and Collateral 1 Total Assets at fair value Derivative contracts $ — $ 6 $ 68 $ — $ 74 Other 33 — — — 33 Nuclear decommissioning trusts: Stocks 2 1,547 — — — 1,547 Fixed Income 3 865 1,751 — — 2,616 Short-term investments, primarily cash equivalents 36 170 — — 206 Subtotal of nuclear decommissioning trusts 4 2,448 1,921 — — 4,369 Total assets 2,481 1,927 68 — 4,476 Liabilities at fair value Derivative contracts — — 1,157 — 1,157 Total liabilities — — 1,157 — 1,157 Net assets (liabilities) $ 2,481 $ 1,927 $ (1,089 ) $ — $ 3,319 1 Represents the netting of assets and liabilities under master netting agreements and cash collateral across the levels of the fair value hierarchy. Netting among positions classified within the same level is included in that level. 2 Approximately 69% and 70% of SCE's equity investments were located in the United States at December 31, 2017 and 2016 , respectively. 3 Includes corporate bonds, which were diversified and included collateralized mortgage obligations and other asset backed securities of $102 million and $79 million at December 31, 2017 and 2016 , respectively. 4 Excludes net payables of $59 million and $127 million at December 31, 2017 and 2016 , which consist of interest and dividend receivables as well as receivables and payables related to SCE's pending securities sales and purchases. Edison International Parent and Other Edison International Parent and Other assets measured at fair value consisted of money market funds of $541 million and $23 million at December 31, 2017 and 2016 , respectively, classified as Level 1. SCE Fair Value of Level 3 The following table sets forth a summary of changes in SCE's fair value of Level 3 net derivative assets and liabilities: December 31, (in millions) 2017 2016 Fair value of net liabilities at beginning of period $ (1,089 ) $ (1,148 ) Total realized/unrealized gains: Included in regulatory assets and liabilities 1 133 59 Contract amendment 2 143 — Normal purchase and normal sale designation 3 914 — Fair value of net assets (liabilities) at end of period $ 101 $ (1,089 ) Change during the period in unrealized gains and losses related to assets and liabilities held at the end of the period $ 100 $ (70 ) 1 Due to regulatory mechanisms, SCE's realized and unrealized gains and losses are recorded as regulatory assets and liabilities. 2 Represents a tolling contract that was amended during the second quarter of 2017, which is no longer accounted for as a derivative as of December 31, 2017. 3 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms. Edison International and SCE recognize the fair value for transfers in and transfers out of each level at the end of each reporting period. There were no material transfers between any levels during 2017 and 2016 . Valuation Techniques Used to Determine Fair Value The process of determining fair value is the responsibility of SCE's risk management department, which reports to SCE's chief financial officer. This department obtains observable and unobservable inputs through broker quotes, exchanges and internal valuation techniques that use both standard and proprietary models to determine fair value. Each reporting period, the risk and finance departments collaborate to determine the appropriate fair value methodologies and classifications for each derivative. Inputs are validated for reasonableness by comparison against prior prices, other broker quotes and volatility fluctuation thresholds. Inputs used and valuations are reviewed period-over-period and compared with market conditions to determine reasonableness. The following table sets forth SCE's valuation techniques and significant unobservable inputs used to determine fair value for significant Level 3 assets and liabilities: Fair Value (in millions) Significant Assets Liabilities Valuation Technique(s) Unobservable Input Range Congestion revenue rights December 31, 2017 $ 102 $ — Market simulation model and auction prices Load forecast 5,002 MW - 22,970 MW Power prices 1 $(15.00) - $120.00 Gas prices 2 $2.46 - $4.37 CAISO CRR auction clearing prices $(9.41) - $8.66 December 31, 2016 67 — Market simulation model and auction prices Load forecast 3,708 MW - 22,840 MW Power prices 1 $3.65 - $99.58 Gas prices 2 $2.51 - $4.87 Tolling 3 December 31, 2016 — 1,154 Option model Volatility of gas prices 15% - 48% Volatility of power prices 29% - 71% Power prices $23.40 - $51.24 1 Prices are in dollars per megawatt-hour. 2 Prices are in dollars per million British thermal units. 3 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms. Level 3 Fair Value Sensitivity Congestion Revenue Rights For CRRs, where SCE is the buyer, generally increases (decreases) in forecasted load in isolation would result in increases (decreases) to the fair value. In general, an increase (decrease) in electricity and gas prices at illiquid locations tends to result in increases (decreases) to fair value; however, changes in electricity and gas prices in opposite directions may have varying results on fair value. Nuclear Decommissioning Trusts SCE's nuclear decommissioning trust investments include equity securities, U.S. treasury securities and other fixed income securities. Equity and treasury securities are classified as Level 1 as fair value is determined by observable market prices in active or highly liquid and transparent markets. The remaining fixed income securities are classified as Level 2. The fair value of these financial instruments is based on evaluated prices that reflect significant observable market information such as reported trades, actual trade information of similar securities, benchmark yields, broker/dealer quotes, issuer spreads, bids, offers and relevant credit information. There are no securities classified as Level 3 in the nuclear decommissioning trusts. SCE's investment policies and CPUC requirements place limitations on the types and investment grade ratings of the securities that may be held by the nuclear decommissioning trust funds. These policies restrict the trust funds from holding alternative investments and limit the trust funds' exposures to investments in highly illiquid markets. With respect to equity and fixed income securities, the trustee obtains prices from third-party pricing services which SCE is able to independently corroborate as described below. The trustee monitors prices supplied by pricing services, including reviewing prices against defined parameters' tolerances and performs research and resolves variances beyond the set parameters. SCE corroborates the fair values of securities by comparison to other market-based price sources obtained by SCE's investment managers. Differences outside established thresholds are followed-up with the trustee and resolved. For each reporting period, SCE reviews the trustee determined fair value hierarchy and overrides the trustee level classification when appropriate. Fair Value of Debt Recorded at Carrying Value The carrying value and fair value of Edison International's and SCE's long-term debt (including current portion of long-term debt) are as follows: December 31, 2017 December 31, 2016 (in millions) Carrying Value 1 Fair Value Carrying Value 1 Fair Value Edison International $ 12,123 $ 13,760 $ 11,156 $ 12,368 SCE 10,907 12,547 10,333 11,539 1 Carrying value is net of debt issuance costs. The fair value of Edison International's and SCE's short-term and long-term debt is classified as Level 2 and is based on evaluated prices that reflect significant observable market information such as reported trades, actual trade information of similar securities, benchmark yields, broker/dealer quotes of new issue prices and relevant credit information. The carrying value of Edison International's and SCE's trade receivables and payables, other investments, and short-term debt approximates fair value.

Debt and Credit Agreements

Debt and Credit Agreements	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt and Credit Agreements	Debt and Credit Agreements Long-Term Debt The following table summarizes long-term debt (rates and terms are as of December 31, 2017 ) of Edison International and SCE: December 31, (in millions) 2017 2016 Edison International Parent and Other: Debentures and notes: 2020 – 2023 (2.125% to 2.95%) $ 1,200 $ 800 Other long-term debt 29 32 Current portion of long-term debt (2 ) (402 ) Unamortized debt discount and issuance costs, net (13 ) (9 ) Total Edison International Parent and Other 1,214 421 SCE: First and refunding mortgage bonds: 2018 – 2047 (1.845% to 6.05%) 9,779 9,357 Pollution-control bonds: 2028 – 2035 (1.375% to 5.0%) 1 909 774 Debentures and notes: 2029 – 2053 (5.06% to 6.65%) 307 307 Current portion of long-term debt (479 ) (579 ) Unamortized debt discount and issuance costs, net (88 ) (105 ) Total SCE 10,428 9,754 Total Edison International $ 11,642 $ 10,175 1 Excludes outstanding bonds that have not been retired and may be remarketed to investors in the future. These bonds have variable rates and are due in 2031 at December 31, 2017 and 2031 and 2033 at December 31, 2016. Edison International and SCE long-term debt maturities over the next five years are the following: (in millions) Edison International SCE 2018 $ 481 $ 479 2019 81 79 2020 481 79 2021 580 579 2022 777 364 Project Financings As of December 31, 2017 and 2016 , indirect subsidiaries of Edison Energy Group owning solar projects had approximately $31 million (includes short-term debt of $16 million ) and $22 million outstanding project debt financings with maturity dates to 2022 with weighted average interest rates of 4.50% and 4.86% . Remaining borrowings available under these agreements are approximately $67 million . Under two of the tax equity financings, tax equity investors in related solar projects receive 99% of taxable profits and losses and tax credits of the projects as determined for federal income tax purposes for a 6 -year period following the completion of the portfolio of projects and receive a priority return of 2% of their investment per year. After the 6 -year period, the tax equity investors receive 5% of the taxable profits and losses and cash flow. A subsidiary of Edison Energy Group has a call option for a 9 -month period following 5 years after completion of the portfolio of projects to purchase the tax equity investors interest and each tax equity investor has the right to put its ownership interest to such subsidiary in the event that the call option is not exercised. Remaining tax equity financings under these agreements are approximately $21 million . Under a third tax equity financing completed in 2017, the tax equity investor in the related solar projects will receive an initial allocation of 99% of taxable losses and tax credits, followed by 67% of taxable income and losses after the initial period and 28.4% of cash flows until certain conditions are met, including attaining a specified rate of return. A subsidiary of Edison Energy Group has the option after certain conditions are met to purchase the tax equity investor's interest at the higher of fair value or the after-tax amount necessary to achieve a specified 20 -year rate of return. Remaining tax equity financings under these agreements are approximately $38 million . An indirect subsidiary of Edison Energy Group also entered into a non-recourse debt financing to support equity contributions in certain solar projects. The maturity date of the borrowings under this agreement is December 31, 2036 . As of December 31, 2017 and 2016 , there was $10 million outstanding under this agreement at a weighted average interest rate of 9% . Liens and Security Interests Almost all of SCE's properties are subject to a trust indenture lien. SCE has pledged first and refunding mortgage bonds as collateral for borrowed funds obtained from pollution-control bonds issued by government agencies. SCE has a debt covenant that requires a debt to total capitalization ratio be met. At December 31, 2017 , SCE was in compliance with this debt covenant and all other financial covenants that affect access to capital. All of the properties subject to the Edison Energy Group project financings discussed above are subject to a lien. Credit Agreements and Short-Term Debt The following table summarizes the status of the credit facilities at December 31, 2017 : (in millions) Edison International Parent SCE Commitment $ 1,250 $ 2,750 Outstanding borrowings (1,139 ) (1,238 ) Outstanding letters of credit — (99 ) Amount available $ 111 $ 1,413 SCE and Edison International Parent have multi-year revolving credit facilities of $2.75 billion and $1.25 billion , respectively, with both maturing in July 2022. SCE's credit facility is generally used to support commercial paper borrowings and letters of credit issued for procurement-related collateral requirements, balancing account undercollections and for general corporate purposes, including working capital requirements to support operations and capital expenditures. Edison International Parent's credit facility is used to support commercial paper borrowings and for general corporate purposes. At December 31, 2017 , commercial paper supported by SCE's credit facility, net of discount, was $738 million at a weighted-average interest rate of 1.75% . In December 2017, SCE borrowed $500 million from the credit facility which had an interest rate of 2.46% on December 31, 2017. In January 2018, SCE repaid its $500 million borrowings with cash on hand. At December 31, 2017 , letters of credit issued under SCE's credit facility aggregated $99 million and are scheduled to expire in twelve months or less. At December 31, 2016 , the outstanding commercial paper, net of discount, was $769 million at a weighted-average interest rate of 0.9% . At December 31, 2017 , Edison International Parent's outstanding commercial paper, net of discount, was $639 million at a weighted-average interest rate of 1.70% . This commercial paper was supported by the $1.25 billion multi-year revolving credit facility. In December 2017, Edison International borrowed $500 million from the credit facility which had an interest rate of 2.56% on December 31, 2017. In January 2018, Edison International repaid its $500 million borrowings with cash on hand. At December 31, 2016 , the outstanding commercial paper, net of discount, was $538 million at a weighted-average interest rate of 0.97% . Debt Financing Subsequent to December 31, 2017 In January 2018, Edison International Parent borrowed $500 million under a Term Loan Agreement due in January 2019, with a variable interest rate based on the London Interbank Offered Rate plus 60 basis points. The proceeds were used to repay Edison International Parent's commercial paper borrowings discussed above.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Derivative financial instruments are used to manage exposure to commodity price risk. These risks are managed in part by entering into forward commodity transactions, including options, swaps and futures. To mitigate credit risk from counterparties in the event of nonperformance, master netting agreements are used whenever possible and counterparties may be required to pledge collateral depending on the creditworthiness of each counterparty and the risk associated with the transaction. Commodity Price Risk Commodity price risk represents the potential impact that can be caused by a change in the market value of a particular commodity. SCE's electricity price exposure arises from energy purchased from and sold to wholesale markets as a result of differences between SCE's load requirements and the amount of energy delivered from its generating facilities and PPAs. SCE's natural gas price exposure arises from natural gas purchased for the Mountainview power plant and peaker plants, QF contracts where pricing is based on a monthly natural gas index and PPAs in which SCE has agreed to provide the natural gas needed for generation, referred to as tolling arrangements. Credit and Default Risk Credit and default risk represent the potential impact that can be caused if a counterparty were to default on its contractual obligations and SCE would be exposed to spot markets for buying replacement power or selling excess power. In addition, SCE would be exposed to the risk of non-payment of accounts receivable, primarily related to the sales of excess power and realized gains on derivative instruments. Certain power contracts contain master netting agreements or similar agreements, which generally allow counterparties subject to the agreement to offset amounts when certain criteria are met, such as in the event of default. The objective of netting is to reduce credit exposure. Additionally, to reduce SCE's risk exposures counterparties may be required to pledge collateral depending on the creditworthiness of each counterparty and the risk associated with the transaction. Certain power contracts contain a provision that requires SCE to maintain an investment grade rating from each of the major credit rating agencies, referred to as a credit-risk-related contingent feature. If SCE's credit rating were to fall below investment grade, SCE may be required to post additional collateral to cover derivative liabilities and the related outstanding payables. The net fair value of all derivative liabilities with these credit-risk-related contingent features was $1 million and $12 million as of December 31, 2017 and 2016 , respectively, for which SCE has posted collateral of less than $1 million and $12 million collateral to its counterparties at the respective dates for its derivative liabilities and related outstanding payables. If the credit-risk-related contingent features underlying these agreements were triggered on December 31, 2017 , SCE would be required to post $20 million of additional collateral of which $19 million is related to outstanding payables that are net of collateral already posted. Fair Value of Derivative Instruments SCE presents its derivative assets and liabilities on a net basis on its consolidated balance sheets when subject to master netting agreements or similar agreements. Derivative positions are offset against margin and cash collateral deposits. In addition, SCE has provided collateral in the form of letters of credit. Collateral requirements can vary depending upon the level of unsecured credit extended by counterparties, changes in market prices relative to contractual commitments and other factors. See Note 4 for a discussion of fair value of derivative instruments. The following table summarizes the gross and net fair values of SCE's commodity derivative instruments: December 31, 2017 Derivative Assets Derivative Liabilities Net Asset (in millions) Short-Term Long-Term Subtotal Short-Term Long-Term Subtotal 2 Commodity derivative contracts Gross amounts recognized $ 106 $ 5 $ 111 $ 3 $ — $ 3 $ 108 Gross amounts offset in the consolidated balance sheets (1 ) — (1 ) (1 ) — (1 ) — Cash collateral posted 1 — — — (1 ) — (1 ) 1 Net amounts presented in the consolidated balance sheets $ 105 $ 5 $ 110 $ 1 $ — $ 1 $ 109 December 31, 2016 Derivative Assets Derivative Liabilities Net Liability (in millions) Short-Term Long-Term Subtotal Short-Term Long-Term Subtotal Commodity derivative contracts Gross amounts recognized $ 74 $ 1 $ 75 $ 217 $ 941 $ 1,158 $ 1,083 Gross amounts offset in the consolidated balance sheets (1 ) — (1 ) (1 ) — (1 ) — Cash collateral posted 1 — — — — — — — Net amounts presented in the consolidated balance sheets $ 73 $ 1 $ 74 $ 216 $ 941 $ 1,157 $ 1,083 1 At December 31, 2016 , SCE had received $2 million of cash collateral that is not offset against derivative assets and is reflected in "Other current liabilities" on the consolidated balance sheets. 2 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms. Income Statement Impact of Derivative Instruments SCE recognizes realized gains and losses on derivative instruments as purchased power expense and expects that such gains or losses will be part of the purchased power costs recovered from customers. As a result, realized gains and losses do not affect earnings, but may temporarily affect cash flows. Due to expected future recovery from customers, unrealized gains and losses are recorded as regulatory assets and liabilities and therefore also do not affect earnings. The remaining effects of derivative activities and related regulatory offsets are reported in cash flows from operating activities in the consolidated statements of cash flows. The following table summarizes the components of SCE's economic hedging activity: Years ended December 31, (in millions) 2017 2016 2015 Realized losses $ (14 ) $ (59 ) $ (148 ) Unrealized gains (losses) 106 84 (182 ) Notional Volumes of Derivative Instruments The following table summarizes the notional volumes of derivatives used for SCE hedging activities: Economic Hedges Unit of December 31, Commodity Measure 2017 2016 Electricity options, swaps and forwards GWh 475 1,816 Natural gas options, swaps and forwards Bcf 143 36 Congestion revenue rights GWh 78,765 93,319 Tolling arrangements GWh — 61,093

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Current and Deferred Taxes Edison International's sources of income before income taxes are: Years ended December 31, (in millions) 2017 2016 2015 Income from continuing operations before income taxes $ 949 $ 1,590 $ 1,568 Income from discontinued operations before income taxes — 1 15 Income before income tax $ 949 $ 1,591 $ 1,583 The components of income tax expense (benefit) by location of taxing jurisdiction are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Current: Federal $ (221 ) $ (46 ) $ 18 $ (253 ) $ 75 $ 72 State 4 33 19 (81 ) 93 127 (217 ) (13 ) 37 (334 ) 168 199 Deferred: Federal 570 176 340 265 112 298 State (72 ) 14 109 39 (24 ) 10 498 190 449 304 88 308 Total continuing operations 281 177 486 (30 ) 256 507 Discontinued operations — (11 ) (21 ) — — — Total $ 281 $ 166 $ 465 $ (30 ) $ 256 $ 507 The components of net accumulated deferred income tax liability are: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Deferred tax assets: Property and software related $ 358 $ 549 $ 357 $ 548 Nuclear decommissioning trust assets in excess of nuclear ARO liability 404 348 404 348 Loss and credit carryforwards 1 1,346 1,418 150 — Regulatory asset 2 812 15 812 15 Pension and postretirement benefits other than pensions 214 300 86 93 Other 277 419 236 408 Sub-total 3,411 3,049 2,045 1,412 Less valuation allowance 28 24 — — Total 3,383 3,025 2,045 1,412 Deferred tax liabilities: Property-related 6,970 10,330 6,962 10,330 Capitalized software costs 160 237 160 237 Regulatory liability 158 134 158 134 Nuclear decommissioning trust assets 404 348 404 348 Postretirement benefits other than pensions 36 13 36 13 Other 140 202 133 148 Total 7,868 11,264 7,853 11,210 Accumulated deferred income tax liability, net 3 $ 4,485 $ 8,239 $ 5,808 $ 9,798 1 As of December 31, 2017, Edison International has recorded a valuation allowance of $28 million for non-California state net operating loss carryforwards estimated to expire unused. In addition, as of December 31, 2017, deferred tax assets for net operating loss and tax credit carryforwards are reduced by unrecognized tax benefits of $77 million and $75 million for Edison International and SCE, respectively. 2 Includes an $809 million deferred tax asset, related to certain regulatory liabilities established as part of Tax Reform discussed below. 3 Included in deferred income taxes and credits on the consolidated balance sheets. On December 22, 2017, Tax Reform was signed into law. This comprehensive reform of tax law reduces the federal corporate income tax rate from 35% to 21% and is generally effective beginning January 1, 2018. US GAAP requires deferred tax assets and liabilities to be measured at the enacted tax rate expected to apply when temporary differences are to be realized or settled. At the date of enactment, Edison International and SCE's deferred taxes were re-measured based upon the new tax rate. Accumulated deferred income tax liabilities, net, were reduced by $4.5 billion and $5.0 billion at Edison International and SCE, respectively. Edison International recorded income tax expense of $466 million at December 31, 2017, primarily related to the re-measurement of the federal net operating loss carryforwards (see below for more information). SCE's re-measurement of deferred taxes was recorded against regulatory assets and liabilities when the pre-tax amounts giving rise to the deferred taxes were created through ratemaking activities. SCE also had shareholder-funded pre-tax amounts that gave rise to the deferred tax assets resulting in income tax expense of $33 million . For property acquired and placed in service by regulated utilities after September 27, 2017, Tax Reform repeals 50% bonus depreciation. As a result, SCE is required to evaluate the contractual terms of its fourth quarter 2017 capital additions to determine whether they still qualify for the prior tax law's 50% bonus depreciation, as compared to no bonus depreciation pursuant to Tax Reform. As of December 31, 2017, SCE has not completed this analysis, but recorded a reasonable estimate of the effects of these changes. SCE expects to complete this analysis during 2018. Net Operating Loss and Tax Credit Carryforwards The amounts of net operating loss and tax credit carryforwards (after-tax) are as follows: Edison International SCE December 31, 2017 (in millions) Loss Carryforwards Credit Carryforwards Loss Carryforwards Credit Carryforwards Expire between 2018 to 2036 $ 901 $ 451 $ 162 $ 25 No expiration date — 71 — 38 Total 1 $ 901 $ 522 $ 162 $ 63 As a result of Tax Reform, Edison International and SCE's federal net operating losses were re-measured at 21% . The reduction in the federal corporate income tax rate does not change the gross dollar value of taxable income that may be offset by NOLs, however that taxable income will only be taxable at 21% in future periods, thus reducing the value of NOLs utilized after 2017. Tax Reform did not impact the valuation of tax credit carryforwards, which directly offset taxes due. Edison International consolidates for federal income tax purposes, but not for financial accounting purposes, a group of wind projects referred to as Capistrano Wind. As a result of Tax Reform, the amount of net operating loss and tax credit carryforwards recognized as part of deferred income taxes was re-measured ( $199 million and $242 million related to Capistrano Wind at December 31, 2017 and 2016, respectively). Under a tax allocation agreement, Edison International has recorded a corresponding liability, which was also re-measured, as part of other long-term liabilities related to its obligation to make payments to Capistrano Wind of these tax benefits when realized. Effective Tax Rate The table below provides a reconciliation of income tax expense computed at the federal statutory income tax rate to the income tax provision: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Income from continuing operations before income taxes $ 949 $ 1,590 $ 1,568 $ 1,106 $ 1,755 $ 1,618 Provision for income tax at federal statutory rate of 35% 332 556 549 387 614 566 Increase in income tax from: Items presented with related state income tax, net: Regulatory asset write-off 1 — — 382 — — 382 State tax, net of federal benefit 2 29 5 8 43 34 Property-related 2 (439 ) (362 ) (341 ) (439 ) (362 ) (341 ) Change related to uncertain tax positions (18 ) (4 ) (67 ) (13 ) (8 ) (94 ) Revised San Onofre Settlement Agreement 3 25 — — 25 — — Share-based compensation 4 (55 ) (28 ) — (11 ) (13 ) — Deferred tax re-measurement 5 466 — — 33 — — Other (32 ) (14 ) (42 ) (20 ) (18 ) (40 ) Total income tax expense (income)from continuing operations $ 281 $ 177 $ 486 $ (30 ) $ 256 $ 507 Effective tax rate 29.6 % 11.1 % 31.0 % (2.7 )% 14.6 % 31.3 % 1 Includes federal and state. 2 Includes incremental repair benefits. See discussion of repair deductions below. In addition, during 2017, SCE recorded $80 million ( $135 million pre-tax) of tax benefits related to tax accounting method changes resulting from the filing of SCE's 2016 tax returns. 3 Includes the write-off of an unrecovered tax regulatory asset related to the Revised San Onofre Settlement Agreement. See Note 11 for further information. 4 Includes state taxes of $(11) million and $(2) million for Edison International and SCE, respectively, for the year ended December 31, 2017. Includes state taxes of $(4) million and $(1) million for Edison International and SCE, respectively, for the year ended December 31, 2016. Refer to Note 1 for further information. 5 In 2017, Edison International and SCE recorded a charge to earnings related to the re-measurement of deferred taxes resulting from Tax Reform. See further discussion above. The CPUC requires flow-through ratemaking treatment for the current tax benefit arising from certain property-related and other temporary differences which reverse over time. Flow-through items reduce current authorized revenue requirements in SCE's rate cases and result in a regulatory asset for recovery of deferred income taxes in future periods. The difference between the authorized amounts as determined in SCE's rate cases, adjusted for balancing and memorandum account activities, and the recorded flow-through items also result in increases or decreases in regulatory assets with a corresponding impact on the effective tax rate to the extent that recorded deferred amounts are expected to be recovered in future rates. For further information, see Note 10. Repair Deductions Edison International made voluntary elections in 2009 and 2011 to change its tax accounting method for certain tax repair costs incurred on SCE's transmission, distribution and generation assets. Incremental repair deductions represent amounts recognized for regulatory accounting purposes in excess of amounts included in the authorized revenue requirements through the general rate case ("GRC") proceedings. As part of the final decision in SCE's 2015 GRC, the CPUC adopted a rate base offset associated with the incremental tax repair deductions during 2012 – 2014. The 2015 rate base offset is $324 million and amortizes on a straight line basis over 27 years. As a result of the rate base offset included in the final decision, SCE recorded an after tax charge of $382 million in 2015 to write down the net regulatory asset for recovery of deferred income taxes related to 2012 – 2014 incremental tax repair deductions which is reflected in "Income tax expense" on the consolidated statements of income. The amount of tax repair deductions the CPUC used to establish the rate base offset was based on SCE's forecast of 2012 – 2014 tax repair deductions from the Notice of Intent filed in the 2015 GRC. The amount of tax repair deductions included in the Notice of Intent was less than the actual tax repair deductions SCE reported on its 2012 through 2014 income tax returns. In April 2016, the CPUC granted SCE's request to reduce SCE's base revenue requirement balancing account ("BRRBA") by $234 million in future periods subject to the timing and final outcome of audits that may be conducted by tax authorities. The refunds resulted in flowing incremental tax benefits for 2012 – 2014 to customers. SCE refunded $133 million ( $79 million after-tax) during the second quarter of 2016. SCE did not record a gain or loss from this reduction. Regulatory assets recorded from flow through tax benefits are recovered through SCE's GRC proceedings. Accounting for Uncertainty in Income Taxes Authoritative guidance related to accounting for uncertainty in income taxes requires an enterprise to recognize, in its financial statements, the best estimate of the impact of a tax position by determining if the weight of the available evidence indicates it is more likely than not, based solely on the technical merits, that the position will be sustained upon examination. The guidance requires the disclosure of all unrecognized tax benefits, which includes both the reserves recorded for tax positions on filed tax returns and the unrecognized portion of affirmative claims. Unrecognized Tax Benefits The following table provides a reconciliation of unrecognized tax benefits for continuing and discontinued operations: Edison International SCE December 31, (in millions) 2017 2016 2015 2017 2016 2015 Balance at January 1, $ 471 $ 529 $ 576 $ 371 $ 353 $ 441 Tax positions taken during the current year: Increases 51 36 54 51 36 48 Tax positions taken during a prior year: Increases — 2 66 — — 23 Decreases 1 (7 ) (96 ) (165 ) (13 ) (18 ) (159 ) Decreases for settlements during the period 2 (83 ) — (2 ) (78 ) — — Balance at December 31, $ 432 $ 471 $ 529 $ 331 $ 371 $ 353 1 Decreases in prior year tax positions for 2016 relate to state tax receivables on various claims. Due to the tax risks associated with these claims, the tax benefits were fully reserved at the time the asset was recorded. During 2016, the Company has determined that it will not recognize these assets so the tax benefit and related tax reserve were written off. Decreases in tax positions for 2015 relate primarily to re-measurement of uncertain tax positions in connection with receipt of the Internal Revenue Service ("IRS") Revenue Agent Report in June 2015. See discussions in Tax Disputes below. 2 In the first quarter of 2017, Edison International settled all open tax positions with the IRS for taxable years 2007 through 2012. As of December 31, 2017 and 2016 , if recognized, $308 million and $347 million , respectively, of the unrecognized tax benefits would impact Edison International's effective tax rate; and $167 million and $243 million , respectively, of the unrecognized tax benefits would impact SCE's effective tax rate. Tax Disputes In the first quarter of 2017, Edison International resolved all open tax positions with the IRS for taxable years 2007 through 2012. Edison International has previously made cash deposits to cover the estimated tax and interest liability from this audit cycle and expects a $7 million refund of this deposited amount. Tax years that remain open for examination by the IRS and the California Franchise Tax Board are 2014 – 2016 and 2010 – 2016 respectively. Edison International has settled all open tax position with the IRS for taxable years prior to 2013. Tax years 1994 – 2006 are currently in settlement negotiations with the California Franchise Tax Board. While we expect to resolve these tax years within the next twelve months, the impacts cannot be reasonably estimated until further progress has been made. Tax years 2007 – 2009 are currently under protest with the California Franchise Tax Board. Accrued Interest and Penalties The total amount of accrued interest and penalties related to income tax liabilities for continuing and discontinued operations are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Accrued interest and penalties $ 115 $ 128 $ 41 $ 41 The net after-tax interest and penalties recognized in income tax expense for continuing and discontinued operations are: Edison International SCE December 31, (in millions) 2017 2016 2015 2017 2016 2015 Net after-tax interest and penalties tax expense (benefit) $ 6 $ 6 $ (9 ) $ 4 $ 2 $ (14 )

Compensation and Benefit Plans

Compensation and Benefit Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Compensation and Benefit Plans	Compensation and Benefit Plans Employee Savings Plan The 401(k) defined contribution savings plan is designed to supplement employees' retirement income. The following employer contributions were made for continuing operations: Edison International SCE (in millions) Years ended December 31, 2017 $ 70 $ 69 2016 69 68 2015 73 72 Pension Plans and Postretirement Benefits Other Than Pensions Pension Plans Noncontributory defined benefit pension plans (some with cash balance features) cover most employees meeting minimum service requirements. SCE recognizes pension expense for its nonexecutive plan as calculated by the actuarial method used for ratemaking. The expected contributions (all by the employer) for Edison International and SCE are approximately $66 million and $50 million , respectively, for the year ending December 31, 2018 . Annual contributions made by SCE to most of SCE's pension plans are anticipated to be recovered through CPUC-approved regulatory mechanisms. The funded position of Edison International's pension is sensitive to changes in market conditions. Changes in overall interest rate levels significantly affect the company's liabilities, while assets held in the various trusts established to fund Edison International's pension are affected by movements in the equity and bond markets. Due to SCE's regulatory recovery treatment, a regulatory asset has been recorded equal to the unfunded status (See Note 10). Information on pension plan assets and benefit obligations for continuing and discontinued operations is shown below. Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Change in projected benefit obligation Projected benefit obligation at beginning of year $ 4,284 $ 4,374 $ 3,791 $ 3,878 Service cost 137 139 129 132 Interest cost 164 171 144 150 Actuarial gain (46 ) (125 ) (74 ) (140 ) Benefits paid (360 ) (275 ) (288 ) (229 ) Projected benefit obligation at end of year $ 4,179 $ 4,284 $ 3,702 $ 3,791 Change in plan assets Fair value of plan assets at beginning of year $ 3,388 $ 3,298 $ 3,172 $ 3,080 Actual return on plan assets 483 262 442 239 Employer contributions 105 103 64 82 Benefits paid (360 ) (275 ) (288 ) (229 ) Fair value of plan assets at end of year $ 3,616 $ 3,388 $ 3,390 $ 3,172 Funded status at end of year $ (563 ) $ (896 ) $ (312 ) $ (619 ) Amounts recognized in the consolidated balance sheets consist of 1 : Long-term assets $ 7 $ 2 $ — $ — Current liabilities (17 ) (50 ) (4 ) (4 ) Long-term liabilities (553 ) (848 ) (308 ) (615 ) $ (563 ) $ (896 ) $ (312 ) $ (619 ) Amounts recognized in accumulated other comprehensive loss consist of: Prior service cost $ (1 ) $ (1 ) $ — $ — Net loss 1 77 93 21 24 $ 76 $ 92 $ 21 $ 24 Amounts recognized as a regulatory asset $ 271 $ 574 $ 271 $ 574 Total not yet recognized as expense $ 347 $ 666 $ 292 $ 598 Accumulated benefit obligation at end of year $ 4,022 $ 4,138 $ 3,585 $ 3,683 Pension plans with an accumulated benefit obligation in excess of plan assets: Projected benefit obligation $ 4,179 $ 4,284 $ 3,702 $ 3,791 Accumulated benefit obligation 4,022 4,138 3,585 3,683 Fair value of plan assets 3,616 3,388 3,390 3,172 Weighted-average assumptions used to determine obligations at end of year: Discount rate 3.46 % 3.94 % 3.46 % 3.94 % Rate of compensation increase 4.10 % 4.00 % 4.10 % 4.00 % 1 The SCE liability excludes a long-term payable due to Edison International Parent of $114 million and $124 million at December 31, 2017 and 2016 , respectively, related to certain SCE postretirement benefit obligations transferred to Edison International Parent. SCE's accumulated other comprehensive loss of $21 million and $24 million at December 31, 2017 and 2016 , respectively, excludes net loss of $19 million and $20 million related to these benefits. Net periodic pension expense components for continuing operations are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Service cost $ 138 $ 139 $ 142 $ 133 $ 136 $ 139 Interest cost 164 172 170 149 156 155 Expected return on plan assets (212 ) (220 ) (233 ) (199 ) (205 ) (217 ) Settlement costs 1 6 — — — — — Amortization of prior service cost 3 4 5 3 4 5 Amortization of net loss 2 21 27 40 17 23 35 Expense under accounting standards 120 122 124 103 114 117 Regulatory adjustment (deferred) (28 ) (21 ) (6 ) (28 ) (21 ) (6 ) Total expense recognized $ 92 $ 101 $ 118 $ 75 $ 93 $ 111 1 Under GAAP, a settlement is recorded when lump-sum payments exceed estimated annual service and interest costs. Lump sum payments made in 2017 to Edison International executives retiring in 2016 from the Executive Retirement Plan exceeded the estimated service and interest costs, resulting in a partial settlement of that plan. A settlement loss of approximately $6.4 million ( $3.8 million after-tax) was recorded at Edison International for the year ended December 31, 2017. 2 Includes the amount of net loss reclassified from other comprehensive loss. The amount reclassified for Edison International was $10 million , $10 million and $14 million for the years ended December 31, 2017, 2016 and 2015, respectively. The amount reclassified for SCE was $6 million , $6 million and $8 million , respectively, for the years ended December 31, 2017, 2016 and 2015, respectively. Other changes in pension plan assets and benefit obligations recognized in other comprehensive loss for continuing operations: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Net loss (gain) $ — $ 6 $ 7 $ 3 $ 4 $ (9 ) Settlement charges (6 ) — — — — — Amortization of net loss (10 ) (10 ) (15 ) (6 ) (6 ) (9 ) Total recognized in other comprehensive loss $ (16 ) $ (4 ) $ (8 ) $ (3 ) $ (2 ) $ (18 ) Total recognized in expense and other comprehensive loss $ 76 $ 97 $ 110 $ 72 $ 91 $ 93 In accordance with authoritative guidance on rate-regulated enterprises, SCE records regulatory assets and liabilities instead of charges and credits to other comprehensive income (loss) for the portion of SCE's postretirement benefit plans that are recoverable in utility rates. The estimated pension amounts that will be amortized to expense in 2018 for continuing operations are as follows: (in millions) Edison International SCE Unrecognized net loss to be amortized 1 $ 8 $ 6 Unrecognized prior service cost to be amortized 3 3 1 The amount of net loss expected to be reclassified from other comprehensive loss for Edison International's continuing operations and SCE is $8 million and $6 million , respectively. Edison International and SCE used the following weighted-average assumptions to determine pension expense for continuing operations: Years ended December 31, 2017 2016 2015 Discount rate 3.94 % 4.18 % 3.85 % Rate of compensation increase 4.00 % 4.00 % 4.00 % Expected long-term return on plan assets 6.50 % 7.00 % 7.00 % The following benefit payments, which reflect expected future service, are expected to be paid: Edison International SCE (in millions) Years ended December 31, 2018 $ 338 $ 304 2019 343 303 2020 327 293 2021 324 287 2022 309 281 2023 – 2027 1,453 1,299 Postretirement Benefits Other Than Pensions ("PBOP(s)") Employees hired prior to December 31, 2017 who are retiring at or after age 55 with at least 10 years of service may be eligible for postretirement medical, dental, and vision benefits. Eligibility for a company contribution toward the cost of these benefits in retirement depends on a number of factors, including the employee's years of service, age, hire date, and retirement date. Under the terms of the Edison International Health and Welfare Benefit Plan ("PBOP Plan"), each participating employer (Edison International or its participating subsidiaries) is responsible for the costs and expenses of all PBOP Plan benefits with respect to its employees and former employees. A participating employer may terminate the PBOP Plan benefits with respect to its employees and former employees, as may SCE (as PBOP Plan sponsor), and, accordingly, the participants' PBOP Plan benefits are not vested benefits. The expected contributions (substantially all of which are expected to be made by SCE) for PBOP benefits are $12 million for the year ended December 31, 2018 . Annual contributions related to SCE employees made to SCE plans are anticipated to be recovered through CPUC-approved regulatory mechanisms and are expected to be, at a minimum, equal to the total annual expense for these plans. SCE has established three voluntary employee beneficiary associations trusts ("VEBA Trusts") that can only be used to pay for retiree health care benefits of SCE. Once funded into the VEBA Trusts, neither SCE nor Edison International can subsequently terminate benefits and recover remaining amounts in the VEBA Trusts. Participants of the PBOP Plan do not have a beneficial interest in the VEBA Trusts. The VEBA Trust assets are sensitive to changes in market conditions. Changes in overall interest rate levels significantly affect the company's liabilities, while assets held in the various trusts established to fund Edison International's other postretirement benefits are affected by movements in the equity and bond markets. Due to SCE's regulatory recovery treatment, the unfunded status is offset by a regulatory asset. Information on PBOP Plan assets and benefit obligations is shown below: Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Change in benefit obligation Benefit obligation at beginning of year $ 2,276 $ 2,350 $ 2,266 $ 2,341 Service cost 31 35 31 34 Interest cost 86 97 85 97 Special termination benefits 1 2 1 2 Plan Amendments — (6 ) — (6 ) Actuarial loss (gain) 24 (110 ) 23 (110 ) Plan participants' contributions 24 19 24 19 Benefits paid (105 ) (111 ) (105 ) (111 ) Benefit obligation at end of year $ 2,337 $ 2,276 $ 2,325 $ 2,266 Change in plan assets Fair value of plan assets at beginning of year $ 2,102 $ 2,036 $ 2,102 $ 2,036 Actual return on assets 297 137 297 137 Employer contributions 12 21 12 21 Plan participants' contributions 24 19 24 19 Benefits paid (105 ) (111 ) (105 ) (111 ) Fair value of plan assets at end of year $ 2,330 $ 2,102 $ 2,330 $ 2,102 Funded status at end of year $ (7 ) $ (174 ) $ 5 $ (164 ) Amounts recognized in the consolidated balance sheets consist of: Long-term assets $ 6 $ — $ 17 $ — Current liabilities (13 ) (14 ) (12 ) (13 ) Long-term liabilities — (160 ) — (151 ) $ (7 ) $ (174 ) $ 5 $ (164 ) Amounts recognized in accumulated other comprehensive loss consist of: Net loss $ 4 $ 4 $ — $ — Amounts recognized as a regulatory (liability) asset (26 ) 136 (26 ) 136 Total not yet recognized as (income) expense $ (22 ) $ 140 $ (26 ) $ 136 Weighted-average assumptions used to determine obligations at end of year: Discount rate 3.70 % 4.29 % 3.70 % 4.29 % Assumed health care cost trend rates: Rate assumed for following year 6.75 % 7.00 % 6.75 % 7.00 % Ultimate rate 5.00 % 5.00 % 5.00 % 5.00 % Year ultimate rate reached 2029 2022 2029 2022 Net periodic PBOP expense components for continuing operations are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Service cost $ 31 $ 35 $ 46 $ 31 $ 34 $ 46 Interest cost 86 97 102 85 97 102 Expected return on plan assets (110 ) (112 ) (116 ) (110 ) (112 ) (116 ) Special termination benefits 1 1 2 1 1 2 1 Amortization of prior service credit (3 ) (2 ) (12 ) (2 ) (2 ) (12 ) Amortization of net loss — — 3 — — 2 Total expense $ 5 $ 20 $ 24 $ 5 $ 19 $ 23 1 Due to the reduction in workforce, SCE has incurred costs for extended retiree health care coverage. In accordance with authoritative guidance on rate-regulated enterprises, SCE records regulatory assets and liabilities instead of charges and credits to other comprehensive income (loss) for the portion of SCE's postretirement benefit plans that are recoverable in utility rates. The estimated PBOP amounts that will be amortized to expense in 2018 for continuing operations are as follows: (in millions) Edison International SCE Unrecognized prior service credit to be amortized $ (1 ) $ (1 ) Edison International and SCE used the following weighted-average assumptions to determine PBOP expense for continuing operations: Years ended December 31, 2017 2016 2015 Discount rate 4.29 % 4.55 % 4.16 % Expected long-term return on plan assets 5.30 % 5.60 % 5.50 % Assumed health care cost trend rates: Current year 7.00 % 7.50 % 7.75 % Ultimate rate 5.00 % 5.00 % 5.00 % Year ultimate rate reached 2022 2022 2021 A one-percentage-point change in assumed health care cost trend rate would have the following effects on continuing operations: Edison International SCE (in millions) One-Percentage-Point Increase One-Percentage-Point Decrease One-Percentage-Point Increase One-Percentage-Point Decrease Effect on accumulated benefit obligation as of December 31, 2017 $ 247 $ (203 ) $ 246 $ (202 ) Effect on annual aggregate service and interest costs 9 (8 ) 9 (8 ) The following benefit payments are expected to be paid: Edison International SCE (in millions) Years ended December 31, 2018 $ 93 $ 93 2019 96 96 2020 100 100 2021 103 103 2022 107 106 2023 – 2027 582 580 Plan Assets Description of Pension and Postretirement Benefits Other than Pensions Investment Strategies The investment of plan assets is overseen by a fiduciary investment committee. Plan assets are invested using a combination of asset classes, and may have active and passive investment strategies within asset classes. Target allocations for 2017 pension plan assets were 29% for U.S. equities, 17% for non-U.S. equities, 35% for fixed income, 15% for opportunistic and/or alternative investments and 4% for other investments. Target allocations for 2017 PBOP plan assets (except for Represented VEBA which is 85% for fixed income, 5% for opportunistic/private equities, and 10% global equities) are 58% for global equities, 29% for fixed income, and 13% for opportunistic and/or alternative investments. Edison International employs multiple investment management firms. Investment managers within each asset class cover a range of investment styles and approaches. Risk is managed through diversification among multiple asset classes, managers, styles and securities. Plan asset classes and individual manager performances are measured against targets. Edison International also monitors the stability of its investment managers' organizations. Allowable investment types include: • United States Equities: Common and preferred stocks of large, medium, and small companies which are predominantly United States-based. • Non-United States Equities: Equity securities issued by companies domiciled outside the United States and in depository receipts which represent ownership of securities of non-United States companies. • Fixed Income: Fixed income securities issued or guaranteed by the United States government, non-United States governments, government agencies and instrumentalities including municipal bonds, mortgage backed securities and corporate debt obligations. A portion of the fixed income positions may be held in debt securities that are below investment grade. Opportunistic, Alternative and Other Investments: • Opportunistic: Investments in short to intermediate term market opportunities. Investments may have fixed income and/or equity characteristics and may be either liquid or illiquid. • Alternative: Limited partnerships that invest in non-publicly traded entities. • Other: Investments diversified among multiple asset classes such as global equity, fixed income currency and commodities markets. Investments are made in liquid instruments within and across markets. The investment returns are expected to approximate the plans' expected investment returns. Asset class portfolio weights are permitted to range within plus or minus 3% . Where approved by the fiduciary investment committee, futures contracts are used for portfolio rebalancing and to reallocate portfolio cash positions. Where authorized, a few of the plans' investment managers employ limited use of derivatives, including futures contracts, options, options on futures and interest rate swaps in place of direct investment in securities to gain efficient exposure to markets. Derivatives are not used to leverage the plans or any portfolios. Determination of the Expected Long-Term Rate of Return on Assets The overall expected long-term rate of return on assets assumption is based on the long-term target asset allocation for plan assets and capital markets return forecasts for asset classes employed. A portion of the PBOP trust asset returns are subject to taxation, so the expected long-term rate of return for these assets is determined on an after-tax basis. Capital Markets Return Forecasts SCE's capital markets return forecast methodologies primarily use a combination of historical market data, current market conditions, proprietary forecasting expertise, complex models to develop asset class return forecasts and a building block approach. The forecasts are developed using variables such as real risk-free interest, inflation, and asset class specific risk premiums. For equities, the risk premium is based on an assumed average equity risk premium of 5% over cash. The forecasted return on private equity and opportunistic investments are estimated at a 2% premium above public equity, reflecting a premium for higher volatility and lower liquidity. For fixed income, the risk premium is based off of a comprehensive modeling of credit spreads. Fair Value of Plan Assets The PBOP Plan and the Southern California Edison Company Retirement Plan Trust (Master Trust) assets include investments in equity securities, U.S. treasury securities, other fixed-income securities, common/collective funds, mutual funds, other investment entities, foreign exchange and interest rate contracts, and partnership/joint ventures. Equity securities, U.S. treasury securities, mutual and money market funds are classified as Level 1 as fair value is determined by observable, unadjusted quoted market prices in active or highly liquid and transparent markets. The fair value of the underlying investments in equity mutual funds are based on stock-exchange prices. The fair value of the underlying investments in fixed-income mutual funds and other fixed income securities including municipal bonds are based on evaluated prices that reflect significant observable market information such as reported trades, actual trade information of similar securities, benchmark yields, broker/dealer quotes, issuer spreads, bids, offers and relevant credit information. Foreign exchange and interest rate contracts are classified as Level 2 because the values are based on observable prices but are not traded on an exchange. Futures contracts trade on an exchange and therefore are classified as Level 1. Common/collective funds and partnerships are measured at fair value using the net asset value per share ("NAV") and have not been classified in the fair value hierarchy. Other investment entities are valued similarly to common/collective funds and are therefore classified as NAV. The Level 1 registered investment companies are either mutual or money market funds. The remaining funds in this category are readily redeemable and classified as NAV and are discussed further at Note 8 to the pension plan master trust investments table below. Edison International reviews the process/procedures of both the pricing services and the trustee to gain an understanding of the inputs/assumptions and valuation techniques used to price each asset type/class. The trustee and Edison International's validation procedures for pension and PBOP equity and fixed income securities are the same as the nuclear decommissioning trusts. For further discussion, see Note 4. The values of Level 1 mutual and money market funds are publicly quoted. The trustees obtain the values of common/collective and other investment funds from the fund managers. The values of partnerships are based on partnership valuation statements updated for cash flows. SCE's investment managers corroborate the trustee fair values. Pension Plan The following table sets forth the Master Trust investments for Edison International and SCE that were accounted for at fair value as of December 31, 2017 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 184 $ 507 $ — $ — $ 691 Corporate stocks 3 718 11 — — 729 Corporate bonds 4 — 676 — — 676 Common/collective funds 5 — — — 705 705 Partnerships/joint ventures 6 — — — 396 396 Other investment entities 7 — — — 262 262 Registered investment companies 8 140 — — — 140 Interest-bearing cash 9 — — — 9 Other — 106 — — 106 Total $ 1,051 $ 1,300 $ — $ 1,363 $ 3,714 Receivables and payables, net (98 ) Net plan assets available for benefits $ 3,616 SCE's share of net plan assets $ 3,390 The following table sets forth the Master Trust investments that were accounted for at fair value as of December 31, 2016 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 217 $ 309 $ — $ — $ 526 Corporate stocks 3 720 15 — — 735 Corporate bonds 4 — 725 — — 725 Common/collective funds 5 — — — 692 692 Partnerships/joint ventures 6 — — — 333 333 Other investment entities 7 — — — 253 253 Registered investment companies 8 124 — — 6 130 Interest-bearing cash 42 — — — 42 Other — 112 — — 112 Total $ 1,103 $ 1,161 $ — $ 1,284 $ 3,548 Receivables and payables, net (160 ) Net plan assets available for benefits $ 3,388 SCE's share of net plan assets $ 3,172 1 These investments are measured at fair value using the net asset value per share practical expedient and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the net plan assets available for benefits. 2 Level 1 U.S. government and agency securities are U.S. treasury bonds and notes. Level 2 primarily relates to the Federal National Mortgage Association and the Federal Home Loan Mortgage Corporation. 3 Corporate stocks are diversified. At December 31, 2017 and 2016 , respectively, performance for actively managed separate accounts is primarily benchmarked against the Russell Indexes ( 54% ) and ( 62% ) and Morgan Stanley Capital International (MSCI) index ( 46% ) and ( 38% ). 4 Corporate bonds are diversified. At December 31, 2017 and 2016 , respectively, this category includes $65 million and $76 million for collateralized mortgage obligations and other asset backed securities of which $18 million and $27 million are below investment grade. 5 At December 31, 2017 and 2016 , respectively, the common/collective assets were invested in equity index funds that seek to track performance of the Standard and Poor's 500 Index ( 41% and 45% ) and Russell 1000 indexes ( 15% ). At both December 31, 2017 and 2016, 15% of the assets in this category are in index funds which seek to track performance in the MSCI All Country World Index exUS. At December 31, 2017 and 2016, a non-index U.S. equity fund representing 25% and 23% of this category for 2017 and 2016 , respectively, is actively managed. 6 At both December 31, 2017 and 2016 , 55% are invested in private equity funds with investment strategies that include branded consumer products, clean technology and California geographic focus companies. At December 31, 2017 and 2016 , respectively, 23% and 22% are invested in publicly traded fixed income securities, 20% and 18% are invested in a broad range of financial assets in all global markets and 2% and 4% of the remaining partnerships are invested in asset backed securities, including distressed mortgages and commercial and residential loans and debt and equity of banks. 7 Other investment entities were primarily invested in (1) emerging market equity securities, (2) a hedge fund that invests through liquid instruments in a global diversified portfolio of equity, fixed income, interest rate, foreign currency and commodities markets, and (3) domestic mortgage backed securities. 8 Level 1 registered investment companies primarily consisted of a global equity mutual fund which seeks to outperform the MSCI World Total Return Index. At December 31, 2017 and 2016 , respectively, approximately 67% and 69% of the publicly traded equity investments, including equities in the common/collective funds, were located in the United States. Postretirement Benefits Other than Pensions The following table sets forth the VEBA Trust assets for Edison International and SCE that were accounted for at fair value as of December 31, 2017 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 398 $ 33 $ — $ — $ 431 Corporate stocks 3 254 — — — 254 Corporate notes and bonds 4 — 845 — — 845 Common/collective funds 5 — — — 569 569 Partnerships 6 — — — 82 82 Registered investment companies 7 37 — — — 37 Interest bearing cash 42 — — — 42 Other 8 5 84 — — 89 Total $ 736 $ 962 $ — $ 651 $ 2,349 Receivables and payables, net (19 ) Combined net plan assets available for benefits $ 2,330 The following table sets forth the VEBA Trust assets for SCE that were accounted for at fair value as of December 31, 2016 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 222 $ 59 $ — $ — $ 281 Corporate stocks 3 230 — — — 230 Corporate notes and bonds 4 — 877 — — 877 Common/collective funds 5 — — — 462 462 Partnerships 6 — — — 79 79 Registered investment companies 7 48 — — 1 49 Interest bearing cash 48 — — — 48 Other 8 4 103 — — 107 Total $ 552 $ 1,039 $ — $ 542 $ 2,133 Receivables and payables, net (31 ) Combined net plan assets available for benefits $ 2,102 1 These investments are measured at fair value using the net asset value per share practical expedient and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the net plan assets available for benefits. 2 Level 1 U.S. government and agency securities are U.S. treasury bonds and notes. Level 2 primarily relates to the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association. 3 Corporate stock performance for actively managed separate accounts is primarily benchmarked against the Russell Indexes ( 64% and 47% ) and the MSCI All Country World Index ( 36% and 53% ) for 2017 and 2016 , respectively. 4 Corporate notes and bonds are diversified and include approximately $36 million and $47 million for commercial collateralized mortgage obligations and other asset backed securities at December 31, 2017 and 2016 , respectively. 5 At December 31, 2017 and 2016 , respectively, 75% and 39% of the common/collective assets are invested in index funds which seek to track performance in the MSCI All Country World Index Investable Market Index and MSCI Europe, Australasia and Far East (EAFE) Index. 17% and 18% are invested in a non-index U.S. equity fund which is actively managed. The remaining assets in this category are primarily invested in emerging market fund at December 31, 2017 and a large cap index fund which seeks to track performance of the Russell 1000 index at December 31, 2016 . 6 At December 31, 2017 and 2016 , respectively, 56% and 59% of the partnerships are invested in private equity and venture capital funds. Investment strategies for these funds include branded consumer products, clean and information technology and healthcare. 33% and 31% are invested in a broad range of financial assets in all global markets. 9% of the remaining partnerships category for both years is invested in asset backed securities including distressed mortgages, distressed companies and commercial and residential loans and debt and equity of banks. 7 At December 31, 2017 , registered investment companies were primarily invested in (1) a money market fund, (2) exchange rate trade funds which seek to track performance of MSCI Emerging Market Index, Russell 2000 Index, and international small cap equities. At December 31, 2016 , Level 1 registered investment companies consist of a money market fund. 8 Other includes $60 million and $76 million of municipal securities at December 31, 2017 and 2016 , respectively. At December 31, 2017 and 2016 , respectively, approximately 61% and 63% of the publicly traded equity investments, including equities in the common/collective funds, were located in the United States. Stock-Based Compensation Edison International maintains a shareholder-approved incentive plan (the 2007 Performance Incentive Plan) that includes stock-based compensation. The maximum number of shares of Edison International's common stock authorized to be issued or transferred pursuant to awards under the 2007 Performance Incentive Plan, as amended, is 66 million shares, plus the number of any shares subject to awards issued under Edison International's prior plans and outstanding as of April 26, 2007, which expire, cancel or terminate without being exercised or shares being issued. As of December 31, 2017 , Edison International had approximately 30 million shares remaining available for new award grants under its stock-based compensation plans. The following table summarizes total expense and tax benefits (expense) associated with stock based compensation: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Stock-based compensation expense 1 : Stock options $ 14 $ 14 $ 14 $ 8 $ 7 $ 8 Performance shares 2 13 7 2 6 4 Restricted stock units 6 6 7 3 3 4 Other 1 1 1 — — — Total stock-based compensation expense $ 23 $ 34 $ 29 $ 13 $ 16 $ 16 Income tax benefits related to stock compensation expense 2 $ 72 $ 41 $ 12 $ 15 $ 20 $ 7 Excess tax benefits 2 — — 15 — — 23 1 Reflected in "Operation and maintenance" on Edison International's and SCE's consolidated statements of income. 2 Under new accounting guidance adopted in 2016, share-based payments may create a permanent difference between the amount of compensation expense recognized for book and tax purposes. Beginning January 1, 2016, the excess tax impact of this permanent difference is recognized in earnings in the period it is created. Stock Options Under the 2007 Performance Incentive Plan, Edison International has granted stock options at exercise prices equal to the closing price at the grant date. Edison International may grant stock options and other awards related to, or with a value derived from, its common stock to directors and certain employees. Options generally expire 10 years after the grant date and vest over a period of four years of continuous service, with expense recognized evenly over the requisite service period, except for awards granted to retirement-eligible participants, as discussed in "Stock-Based Compensation" in Note 1. Additionally, Edison International will substitute cash awards to the extent necessary to pay tax withholding or any government levies. The fair value for each option granted was determined as of the grant date using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires various assumptions noted in the following table: Years ended December 31, 2017 2016 2015 Expected terms (in years) 5.7 5.9 5.9 Risk-free interest rate 2.1% - 2.3% 1.2% – 2.2% 1.6% – 2.1% Expected dividend yield 2.7% - 3.8% 2.5% – 3.0% 2.6% – 3.2% Weighted-average expected dividend yield 2.7% 2.9% 2.6% Expected volatility 17.8% - 20.9% 17.2% – 17.5% 16.4% – 17.0% Weighted-average volatility 17.9% 17.4% 16.5% The expected term represents the period of time for which the options are expected to be outstanding and is primarily based on historical exercise and post-vesting cancellation experience and stock price history. The risk-free interest rate for periods within the contractual life of the option is based on a zero coupon U.S. Treasury STRIPS (separate trading of registered interest and principal of securities) whose maturity equals the option's expected term on the measurement date. Expected volatility is based on the historical volatility of Edison International's common stock for the length of the option's expected term for 2017 . The volatility period used was 68 months , 71 months and 71 months at December 31, 2017 , 2016 and 2015 , respectively. The following is a summary of the status of Edison International's stock

Investments

Investments	12 Months Ended
	Dec. 31, 2017
Regulated Entity, Other Assets, Noncurrent [Abstract]
Investments	Investments Nuclear Decommissioning Trusts Future decommissioning costs related to SCE's nuclear assets are expected to be funded from independent decommissioning trusts. The following table sets forth amortized cost and fair value of the trust investments (see Note 4 for a discussion of fair value of the trust investments): Longest Maturity Date Amortized Cost Fair Value December 31, (in millions) 2017 2016 2017 2016 Stocks — $ 236 $ 319 $ 1,596 $ 1,547 Municipal bonds 2054 643 659 768 766 U.S. government and agency securities 2067 1,235 1,131 1,319 1,191 Corporate bonds 2057 579 600 643 659 Short-term investments and receivables/payables 1 One-year 110 75 114 79 Total $ 2,803 $ 2,784 $ 4,440 $ 4,242 1 Short-term investments include $29 million and $114 million of repurchase agreements payable by financial institutions which earn interest, are fully secured by U.S. Treasury securities and mature by January 2, 2018 and January 4, 2017 as of December 31, 2017 and 2016 , respectively. Trust fund earnings (based on specific identification) increase the trust fund balance and the ARO regulatory liability. Unrealized holding gains, net of losses, were $1.6 billion and $1.5 billion at December 31, 2017 and 2016 , respectively, and other-than-temporary impairments of $143 million and $170 million at the respective periods. Trust assets are used to pay income taxes. Deferred tax liabilities related to net unrealized gains at December 31, 2017 were $404 million . Accordingly, the fair value of trust assets available to pay future decommissioning costs, net of deferred income taxes, totaled $4.0 billion at December 31, 2017 . Gross realized gains were $244 million , $92 million and $326 million for the years ended December 31, 2017, 2016 and 2015, respectively. Gross realized losses were $23 million , $19 million and $26 million for the years ended December 31, 2017, 2016 and 2015, respectively. Due to regulatory mechanisms, changes in assets of the trusts from income or loss items have no impact on operating revenue or earnings. Acquisitions On December 31, 2015 , Edison Energy acquired three businesses for an aggregate purchase price of approximately $100 million , of which $90 million was allocated to goodwill and identifiable intangibles. Under the terms of the acquisition of one of the agreements, the sellers were entitled to additional consideration (earn-out) in the event that certain financial thresholds were achieved. During the second quarter of 2016, Edison Energy entered into an agreement to buy-out this earn-out provision and recorded an after-tax charge of $13 million . The buy-out was completed, together with modification to employment contracts, in order to align long-term incentive compensation. During 2016 and 2017, a subsidiary of SoCore Energy acquired 100% equity interests in six solar garden development projects ( 42 MWdc) in Minnesota from SunEdison for $19.4 million . SoCore Energy also reimbursed SunEdison $2.6 million of project-specific interconnection costs.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	12 Months Ended
	Dec. 31, 2017
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities Included in SCE's regulatory assets and liabilities are regulatory balancing accounts. CPUC authorized balancing account mechanisms require SCE to refund or recover any differences between forecasted and actual costs. The CPUC has authorized balancing accounts for specified costs or programs such as fuel, purchased-power, demand-side management programs, nuclear decommissioning and public purpose programs. Certain of these balancing accounts include a return on rate base of 7.90% in 2017 and 2016 . The CPUC authorizes the use of a balancing account to recover from or refund to customers differences in revenue resulting from actual and forecasted electricity sales. The CPUC has also established a tax accounting memorandum account ("TAMA") to track tax benefits or costs associated with certain events to be adjusted annually in rates, including tax accounting method changes, changes in tax laws and regulations impacting depreciation or tax repair deductions, forecasted and actual differences in tax repair deductions. Amounts included in regulatory assets and liabilities are generally recorded with corresponding offsets to the applicable income statement accounts. Regulatory Assets SCE's regulatory assets included on the consolidated balance sheets are: December 31, (in millions) 2017 2016 Current: Regulatory balancing accounts $ 484 $ 135 Power contracts and energy derivatives 203 150 Unamortized investments, net of accumulated amortization 5 49 Other 11 16 Total current 703 350 Long-term: Deferred income taxes, net of liabilities 3,143 4,478 Pensions and other postretirement benefits 271 710 Power contracts and energy derivatives 799 947 Unamortized investments, net of accumulated amortization 123 80 San Onofre 72 857 Unamortized loss on reacquired debt 168 184 Regulatory balancing accounts 143 66 Environmental remediation 144 126 Other 51 7 Total long-term 4,914 7,455 Total regulatory assets $ 5,617 $ 7,805 SCE's regulatory assets related to power contracts and energy derivatives are primarily an offset to unrealized losses on derivatives. The liabilities for the power contracts will be amortized over the remaining contract terms, approximately 3 to 6 years and will not earn a rate of return. SCE's current and long-term unamortized investments include legacy meters retired as part of the Edison SmartConnect ® program and beyond the meters. SCE's unamortized investments related to legacy meters were fully recovered in 2017 and earned a rate of return of 6.46% in 2017 and 2016. SCE's regulatory assets related to deferred income taxes represent tax benefits passed through to customers. The CPUC requires SCE to flow through certain deferred income tax benefits to customers by reducing electricity rates, thereby deferring recovery of such amounts to future periods. Based on current regulatory ratemaking and income tax laws, SCE expects to recover its regulatory assets related to deferred income taxes over the life of the assets that give rise to the accumulated deferred income taxes, approximately from 1 to 60 years. As a result of Tax Reform, SCE re-measured its deferred tax assets and liabilities as of December 31, 2017. For further information, see Note 7. SCE's regulatory assets related to pensions and other post-retirement plans represent the unfunded net loss and prior service costs of the plans (see "Pension Plans and Postretirement Benefits Other than Pensions" discussion in Note 8). This amount is being recovered through rates charged to customers. SCE has long-term unamortized investments which primarily include nuclear assets related to Palo Verde. Nuclear assets related to Palo Verde are expected to be recovered by 2047 and earned a return of 7.90% in 2017 and 2016. In accordance with the Revised San Onofre Settlement Agreement, SCE wrote down the San Onofre regulatory asset. SCE has requested to apply $72 million of the U.S. Department of Energy ("DOE") proceeds, currently reflected as a regulatory liability in the DOE litigation memorandum account, against the remaining San Onofre regulatory asset. See Note 11 for further information. SCE's net regulatory asset related to its unamortized loss on reacquired debt will be recovered over the original amortization period of the reacquired debt over periods ranging from 10 to 35 years or the amortization period of life of the new issue if the debt is refunded or refinanced. SCE's regulatory assets related to environmental remediation represents a portion of the costs incurred at certain sites that SCE is allowed to recover through customer rates. See "Environmental Remediation" discussed in Note 11. Regulatory Liabilities SCE's regulatory liabilities included on the consolidated balance sheets are: December 31, (in millions) 2017 2016 Current: Regulatory balancing accounts $ 1,009 $ 736 Energy derivatives 74 — Other 38 20 Total current 1,121 756 Long-term: Costs of removal 2,741 2,847 Re-measurement of deferred taxes 2,892 — Recoveries in excess of ARO liabilities 1,575 1,639 Regulatory balancing accounts 1,316 1,180 Other postretirement benefits 26 — Other 64 60 Total long-term 8,614 5,726 Total regulatory liabilities $ 9,735 $ 6,482 SCE's regulatory liabilities related to costs of removal represent differences between asset removal costs recorded and amounts collected in rates for those costs. As a result of Tax Reform, SCE's deferred tax assets and liabilities were re-measured at December 31, 2017 resulting in an increase in regulatory liabilities which is subject to change based on the outcome of the regulatory process. The regulatory liabilities are generally expected to be refunded to customers over the lives of the assets and liabilities that gave rise to the deferred taxes. For further information, see Note 7. SCE's regulatory liabilities related to recoveries in excess of ARO liabilities represents the cumulative differences between ARO expenses and amounts collected in rates primarily for the decommissioning of the SCE's nuclear generation facilities. Decommissioning costs recovered through rates are primarily placed in nuclear decommissioning trusts. This regulatory liability also represents the deferral of realized and unrealized gains and losses on the nuclear decommissioning trust investments. See Note 9 for further discussion. Net Regulatory Balancing Accounts Balancing account over and under collections represent differences between cash collected in current rates for specified forecasted costs and such costs that are actually incurred. Undercollections are recorded as regulatory balancing account assets. Overcollections are recorded as regulatory balancing account liabilities. With some exceptions, SCE seeks to adjust rates on an annual basis or at other designated times to recover or refund the balances recorded in its balancing accounts. Regulatory balancing accounts that SCE does not expect to collect or refund in the next 12 months are reflected in the long-term section of the consolidated balance sheets. Regulatory balancing accounts do not have the right of offset and are presented gross in the consolidated balance sheets. Under and over collections accrue interest based on a three-month commercial paper rate published by the Federal Reserve. The following table summarizes the significant components of regulatory balancing accounts included in the above tables of regulatory assets and liabilities: December 31, (in millions) 2017 2016 Asset (liability) Energy resource recovery account $ 464 $ (20 ) New system generation balancing account (197 ) (6 ) Public purpose programs and energy efficiency programs (1,145 ) (992 ) Base revenue requirement balancing account (200 ) (426 ) Tax accounting memorandum account and pole loading balancing account (259 ) (142 ) DOE litigation memorandum account (156 ) (122 ) Greenhouse gas auction revenue (22 ) 31 FERC balancing accounts (205 ) (69 ) Other 22 31 Liability $ (1,698 ) $ (1,715 )

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Power Purchase Agreements SCE entered into various agreements to purchase power, electric capacity and other energy products. At December 31, 2017 , the undiscounted future expected payments for the SCE power purchase agreements (primarily related to renewable energy contracts), which were approved by the CPUC and met other critical contract provisions (including completion of major milestones for construction), were as follows: (in millions) Total 2018 $ 2,513 2019 2,513 2020 2,614 2021 2,582 2022 2,562 Thereafter 27,093 Total future commitments $ 39,877 Additionally, SCE has signed contracts (including capacity reduction contracts with customers) that have not met the critical contract provisions that would increase contractual obligations by $29 million in 2018, $109 million in 2019, $231 million in 2020, $312 million in 2021, $301 million in 2022 and $3.8 billion thereafter, if all critical contract provisions are completed. Costs incurred for power purchase agreements were $3.6 billion in 2017, $3.3 billion in 2016 and $3.2 billion in 2015, which include costs associated with contracts with terms of less than one year. Certain power purchase agreements that SCE entered into with independent power producers are accounted for as leases. The following table shows the future minimum lease payments due under the contracts that are treated as operating and capital leases (these amounts are also included in the table above). Due to the inherent uncertainty associated with the reliability of the fuel source, expected purchases from most renewable energy contracts do not meet the definition of a minimum lease payment and have been excluded from the operating and capital lease table below but remain in the table above. The future minimum lease payments for capital leases are discounted to their present value in the table below using SCE's incremental borrowing rate at the inception of the leases. The amount of this discount is shown in the table below as the amount representing interest. (in millions) Operating Leases Capital Leases 2018 $ 335 $ 2 2019 262 2 2020 234 2 2021 198 3 2022 174 3 Thereafter 1,222 21 Total future commitments $ 2,425 $ 33 Amount representing executory costs (15 ) Amount representing interest (8 ) Net commitments $ 10 Operating lease expense for power purchase agreements was $2.3 billion in 2017 , and $1.9 billion in 2016 and $ 1.7 billion in 2015 (including contingent rents of $1.8 billion in 2017 , $1.4 billion in 2016 and $1.1 billion in 2015 ). Contingent rents for capital leases were $99 million in 2017, $109 million in 2016 and less than $1 million in 2015. The timing of SCE's recognition of the lease expense conforms to ratemaking treatment for SCE's recovery of the cost of electricity and is included in purchased power. Other Lease Commitments The following summarizes the estimated minimum future commitments for SCE's non-cancelable other operating leases (primarily related to vehicles, office space and other equipment): (in millions) Total 2018 $ 48 2019 37 2020 27 2021 20 2022 15 Thereafter 99 Total future commitments $ 246 Operating lease expense for other leases were $59 million in 2017 , $68 million in 2016 and $80 million in 2015 . Certain leases on office facilities contain escalation clauses requiring annual increases in rent. The rentals payable under these leases may increase by a fixed amount each year, a percentage over base year, or the consumer price index. Other Commitments The following summarizes the estimated minimum future commitments for SCE's other commitments: (in millions) 2018 2019 2020 2021 2022 Thereafter Total Other contractual obligations $ 127 $ 72 $ 69 $ 45 $ 46 $ 345 $ 704 Costs incurred for other commitments were $75 million in 2017 , $141 million in 2016 and $182 million in 2015 . SCE has fuel supply contracts for Palo Verde which require payment only if the fuel is made available for purchase. SCE also has commitments related to maintaining reliability and expanding SCE's transmission and distribution system. The table above does not include asset retirement obligations, which are discussed in Note 1. Indemnities Edison International and SCE have various financial and performance guarantees and indemnity agreements which are issued in the normal course of business. Edison International and SCE have provided indemnifications through contracts entered into in the normal course of business. These are primarily indemnifications against adverse litigation outcomes in connection with underwriting agreements, and indemnities for specified environmental liabilities and income taxes with respect to assets sold. Edison International's and SCE's obligations under these agreements may or may not be limited in terms of time and/or amount, and in some instances Edison International and SCE may have recourse against third parties. Edison International and SCE have not recorded a liability related to these indemnities. The overall maximum amount of the obligations under these indemnifications cannot be reasonably estimated. SCE has indemnified the City of Redlands, California in connection with the Mountainview power plant's California Energy Commission permit for cleanup or associated actions related to groundwater contaminated by perchlorate due to the disposal of filter cake at the City's solid waste landfill. The obligations under this agreement are not limited to a specific time period or subject to a maximum liability. SCE has not recorded a liability related to this indemnity. Contingencies In addition to the matters disclosed in these Notes, Edison International and SCE are involved in other legal, tax and regulatory proceedings before various courts and governmental agencies regarding matters arising in the ordinary course of business. Edison International and SCE believe the outcome of these other proceedings will not, individually or in the aggregate, materially affect its financial position, results of operations and cash flows. Southern California Wildfires In December 2017, several wind-driven wildfires (the "December 2017 Wildfires") impacted portions of SCE's service territory and caused substantial damage to both residential and business properties and service outages for SCE customers. The largest of these fires, known as the Thomas Fire, originated in Ventura County and burned acreage located in both Ventura and Santa Barbara Counties. According to the most recent California Department of Forestry and Fire Protection ("Cal Fire") incident information reports, the Thomas Fire burned over 280,000 acres, destroyed an estimated 1,063 structures, damaged an estimated 280 structures and resulted in two fatalities. During 2017, SCE incurred approximately $35 million of capital expenditures related to restoration of service resulting from the December 2017 Wildfires. The causes of the December 2017 Wildfires are being investigated by Cal Fire and other fire agencies. SCE believes the investigations include the possible role of SCE's facilities. SCE expects that one or more of the fire agencies will ultimately issue reports concerning the origins and causes of the December 2017 Wildfires but cannot predict when these reports will be released or if any findings will be issued before the investigations are completed. Any potential liability of SCE for December 2017 Wildfire-related damages will depend on a number of factors, including whether SCE is determined to have substantially caused, or contributed to, the damages and whether parties seeking recovery of damages will be required to show negligence in addition to causation. Certain California courts have previously found utilities to be strictly liable for property damage, regardless of fault, by applying the theory of inverse condemnation when a utility's facilities were determined to be a substantial cause of a wildfire that caused the property damage. The rationale stated by these courts for applying this theory to investor-owned utilities is that property losses resulting from a public improvement, such as the distribution of electricity, can be spread across the larger community that benefited from such improvement. However, in December 2017 , the CPUC issued a decision denying the investor-owned utility's request to include in its rates uninsured wildfire-related costs arising from several 2007 fires, finding that the investor-owned utility did not prudently manage and operate its facilities prior to or at the outset of the 2007 wildfires. In addition to liability for property damages, when inverse condemnation is found to be applicable to a utility, the utility may be held liable, without regard to fault, for associated interest and attorney's fees (collectively, "Property Losses"). If inverse condemnation is held to be inapplicable to SCE in connection with the December 2017 Wildfires, SCE could still be held liable for Property Losses if those losses were found to have been proximately caused by SCE’s negligence. If SCE was found negligent, SCE also could be held liable for fire suppression costs, business interruption losses, evacuation costs, medical expenses and personal injury/wrongful death claims. These potential liabilities, in the aggregate, could be substantial. Additionally, SCE could potentially be subject to fines for alleged violations of CPUC rules and laws in connection with the December 2017 Wildfires. SCE is aware of multiple lawsuits filed related to the December 2017 Wildfires naming SCE as a defendant. One of these lawsuits also named Edison International as a defendant. At least four of these lawsuits were filed as purported class actions. The lawsuits, which have been filed in the superior courts of Ventura, Santa Barbara and Los Angeles Counties allege, among other things, negligence, inverse condemnation, trespass, private nuisance, and violations of the public utility and health and safety codes. SCE expects to be the subject of additional lawsuits related to the December 2017 Wildfires. The litigation could take a number of years to be resolved because of the complexity of the matters and the time needed to complete the ongoing investigations. Given the preliminary stages of the investigations and the uncertainty as to the causes of the December 2017 Wildfires, and the extent and magnitude of potential damages, Edison International and SCE are currently unable to reasonably estimate whether SCE will incur material losses and, if so, the range of possible losses that could be incurred. SCE has approximately $1 billion of wildfire-specific insurance coverage, subject to a self-insured retention of $10 million per occurrence, for wildfire-related claims for the period ending on May 31, 2018 . SCE also has approximately $300 million of additional insurance coverage for wildfire-related occurrences for the period from December 31, 2017 to December 31, 2018 which may be used in addition to the $1 billion in wildfire insurance for wildfire events occurring on or after December 31, 2017 and on or before May 31, 2018 , and would be available for new wildfire events, if any, occurring after May 31, 2018 and on or before December 30, 2018 . Various coverage limitations within the policies that make up SCE's wildfire insurance coverage could result in material self-insured costs in the event of multiple wildfire occurrences during a policy period. SCE also has other general liability insurance coverage of approximately $450 million but it is uncertain whether these other policies would apply to liabilities alleged to be related to wildfires. Should responsibility for damages be attributed to SCE for a significant portion of the losses related to the December 2017 Wildfires, SCE's insurance may not be sufficient to cover all such damages. SCE or its vegetation management contractors may experience coverage reductions and/or increased insurance costs in future years. No assurance can be given that future losses will not exceed the limits of insurance coverage. In addition, SCE may not be authorized to recover its uninsured damages through customer rates if, for example, the CPUC finds that the damages were incurred because SCE was not a prudent manager of its facilities. The CPUC's Safety and Enforcement Division ("SED") is conducting an investigation to assess the compliance of SCE’s facilities with applicable rules and regulations in areas impacted by the December 2017 Wildfires. Edison International and SCE are pursuing legislative, regulatory and legal solutions to the application of a strict liability standard to wildfire-related damages without the ability to recover resulting costs from customers. Edison International and SCE cannot predict whether or when a solution mitigating the significant risk faced by a California investor-owned utility related to wildfires will be achieved. Montecito Mudslides In January 2018 , torrential rains in Santa Barbara County produced mudslides and flooding in Montecito and surrounding areas (the "Montecito Mudslides"). According to Santa Barbara County, the Montecito Mudslides destroyed an estimated 135 structures, damaged an estimated 324 structures, and resulted in at least 21 fatalities, with two additional fatalities presumed. Six of the lawsuits mentioned above allege that SCE has responsibility for the Thomas Fire and that the Thomas Fire proximately caused the Montecito Mudslides, resulting in the plaintiffs' claimed damages. SCE expects that additional lawsuits related to the Montecito Mudslides will be filed. As noted above, the cause of the Thomas Fire has not been determined. In the event that SCE is determined to have liability for damages caused by the Thomas Fire, SCE cannot predict whether the courts will conclude that the Montecito Mudslides were caused by the Thomas Fire or that SCE is responsible or liable for damages caused by the Montecito Mudslides. As a result, Edison International and SCE are currently unable to reasonably estimate whether SCE will incur material losses and, if so, the range of possible losses that could be incurred. If it is determined that the Montecito Mudslides were caused by the Thomas Fire and that SCE is responsible or liable for damages caused by the Montecito Mudslides, then SCE's insurance coverage for such losses may be limited to its wildfire insurance. Additionally, if SCE is determined to be liable for a significant portion of costs associated with the Montecito Mudslides, SCE's insurance may not be sufficient to cover all such damages and SCE may be unable to recover any uninsured losses. If it is ultimately determined that SCE is legally responsible for losses caused by the Montecito Mudslides, SCE could be held liable for resulting Property Losses if inverse condemnation is found applicable. If SCE is determined to have been negligent, in addition to Property Losses, SCE could be liable for business interruption losses, evacuation costs, clean-up costs, medical expenses and personal injury/wrongful death claims associated with the Montecito Mudslides. These liabilities, in the aggregate, could be substantial. SCE cannot predict whether it will be subjected to regulatory fines related to the Montecito Mudslides. Permanent Retirement of San Onofre Replacement steam generators were installed at San Onofre in 2010 and 2011. On January 31, 2012, a leak suddenly occurred in one of the heat transfer tubes in San Onofre's Unit 3 steam generators. The Unit was safely taken off-line and subsequent inspections revealed excessive tube wear. Unit 2 was off-line for a planned outage when areas of unexpected tube wear were also discovered. On June 6, 2013, SCE decided to permanently retire Units 2 and 3. San Onofre CPUC Proceedings In November 2014, the CPUC approved the San Onofre OII Settlement Agreement by and among The Utility Reform Network ("TURN"), the CPUC's Office of Ratepayers Advocates ("ORA"), San Diego Gas & Electric ("SDG&E"), the Coalition of California Utility Employees, and Friends of the Earth (the "Prior San Onofre Settlement Agreement"), which, at the time, resolved the CPUC's investigation regarding the steam generator replacement project at San Onofre and the related outages and subsequent shutdown of San Onofre. Subsequently, the San Onofre Order Instituting Investigation ("OII") proceeding record was reopened by a joint ruling of the Assigned Commissioner and the Assigned administrative law judge ("ALJ") to consider whether, in light of the Company not reporting certain ex parte communications on a timely basis, the Prior San Onofre Settlement Agreement remained reasonable, consistent with the law and in the public interest, which is the standard the CPUC applies in reviewing settlements submitted for approval. Entry into Revised Settlement and Utility Shareholder Agreements On January 30, 2018 , SCE, SDG&E, The Alliance for Nuclear Responsibility, The California Large Energy Consumers Association, California State University, Citizens Oversight dba Coalition to Decommission San Onofre, the Coalition of California Utility Employees, the Direct Access Customer Coalition, Ruth Henricks, ORA, TURN, and Women's Energy Matters (the "OII Parties") entered into a Revised San Onofre Settlement Agreement in the San Onofre OII proceeding (the "Revised San Onofre Settlement Agreement"). If approved by the CPUC, the Revised San Onofre Settlement Agreement will resolve all issues under consideration in the San Onofre OII and will modify the Prior San Onofre Settlement Agreement. If approved by the CPUC, the Revised San Onofre Settlement Agreement will also result in the dismissal of a federal lawsuit currently pending in the 9th Circuit Court of Appeals challenging the CPUC's authority to permit rate recovery of San Onofre costs. The Revised San Onofre Settlement Agreement was the result of multiple mediation sessions in 2017 and January 2018 and was signed on January 30, 2018 following a settlement conference in the OII, as required under CPUC rules. Implementation of the terms of the Revised San Onofre Settlement Agreement is subject to the approval of the CPUC, as to which there is no assurance. The OII Parties have agreed to exercise their best efforts to obtain CPUC approval, but there can be no certainty of when or what the CPUC will actually decide. On February 6, 2018 , the San Onofre OII Assigned Commissioner and Assigned ALJ issued a joint ruling advising the parties, among other things, that (i) the CPUC will need additional information and that the parties should be prepared to submit joint testimony in support of the Revised San Onofre Settlement Agreement on March 26, 2018 ; (ii) there will be public participation hearings and at least one additional status conference; and (iii) another ruling will be issued with further direction. Disallowances, Refunds and Recoveries If the Revised San Onofre Settlement Agreement is approved by the CPUC, SCE and SDG&E (the "Utilities") will cease rate recovery of San Onofre costs as of the date their combined remaining San Onofre regulatory assets equal $775 million (the "Cessation Date"). SCE has previously requested the CPUC to authorize SCE to reduce the San Onofre regulatory asset by applying $72 million of proceeds received from litigation with the DOE related to DOE's failure to meet its obligation to begin accepting spent nuclear fuel from San Onofre. If that request is approved by the CPUC, the Cessation Date is estimated to be December 19, 2017. If that request is not approved by the CPUC, the Cessation Date is estimated to be April 21, 2018. The Utilities will refund to customers San Onofre-related amounts recovered in rates after the Cessation Date. SCE will retain amounts collected under the Prior San Onofre Settlement Agreement before the Cessation Date. SCE also will retain $47 million of proceeds received in 2017 from arbitration with Mitsubishi Heavy Industries ("MHI") over MHI's delivery of faulty steam generators. In the Revised San Onofre Settlement Agreement, SCE retains the right to sell its stock of nuclear fuel and not share such proceeds with customers, as was provided in the Prior San Onofre Settlement Agreement. SCE intends to sell its nuclear fuel inventory as market conditions warrant. Sales of nuclear fuel may be significant. Under the Prior San Onofre Settlement Agreement, the Utilities agreed to fund $25 million for a Research, Development and Demonstration program that is intended to develop technologies and methodologies to reduce greenhouse gas emissions ("GHG Reduction Program"). The Utilities' funding obligation is reduced to $12.5 million under the Revised San Onofre Settlement Agreement. If approved by the CPUC, the Revised San Onofre Settlement Agreement will also provide certain exclusions from the determination of SCE's ratemaking capital structure. Notwithstanding that SCE will no longer recover its San Onofre regulatory asset, the debt borrowed to finance the regulatory asset will continue to be excluded from SCE's ratemaking capital structure. Additionally, SCE may exclude the after-tax charge resulting from the implementation of the Revised San Onofre Settlement Agreement from its ratemaking capital structure. Accounting and Financial Impacts Under the Prior San Onofre Settlement Agreement, GAAP required that previously incurred costs related to San Onofre Units 2 & 3 be reflected as a regulatory asset to the extent that management concluded the costs were probable of recovery through future rates. GAAP also requires that amounts collected that are probable of refund to customers be recorded as regulatory liabilities. In the fourth quarter of 2017 , regulatory assets and liabilities were adjusted based on the probable approval of the Revised San Onofre Settlement Agreement. In connection with the Revised San Onofre Settlement Agreement, and in exchange for the release of certain San Onofre-related claims, the Utilities entered into an agreement ("Utility Shareholder Agreement") in which SCE has agreed to pay SDG&E the amounts SDG&E would have received in rates under the Prior San Onofre Settlement Agreement but will not receive upon implementation of the Revised San Onofre Settlement Agreement. As of December 19, 2017 , SDG&E's regulatory asset was approximately $151 million . In the fourth quarter of 2017 , SCE recorded an accrued liability of $143 million for the estimated present value of this obligation. The following table summarizes the financial impact of the Revised San Onofre Settlement Agreement and the Utility Shareholder Agreement: (in millions) San Onofre base regulatory asset $ 696 DOE litigation regulatory liability (72 ) MHI Arbitration regulatory liability (47 ) GHG Reduction Program (10 ) Other 6 Present value of Utility Shareholder Agreement 143 Total pre-tax charge $ 716 Total after-tax charge $ 448 Additional Challenges related to the Settlement of San Onofre CPUC Proceedings A federal lawsuit challenging the CPUC's authority to permit rate recovery of San Onofre costs and an application to the CPUC for rehearing of its decision approving the San Onofre OII Settlement Agreement were filed in November and December 2014 , respectively. In April 2015 , the federal lawsuit was dismissed with prejudice and the plaintiffs in that case appealed the dismissal to the Ninth Circuit in May 2015 . In light of the San Onofre OII meet-and-confer sessions, the Ninth Circuit cancelled the hearing that had been scheduled for February 9, 2017 and ordered the parties to notify the Ninth Circuit of the status of the San Onofre OII by May 1, 2017 and periodically thereafter. In October 2017 , the Ninth Circuit scheduled a hearing for February 13, 2018 and directed the parties to file a status report on January 30, 2018 . As part of the Revised San Onofre Settlement Agreement, the plaintiffs agreed to dismiss this case with prejudice. In July 2015 , a purported securities class action lawsuit was filed in federal court against Edison International, its then Chief Executive Officer and its then Chief Financial Officer. The complaint was later amended to include SCE's former President as a defendant. The lawsuit alleges that the defendants violated the securities laws by failing to disclose that Edison International had ex parte contacts with CPUC decision-makers regarding the San Onofre OII that were either unreported or more extensive than initially reported. The initial complaint purports to be filed on behalf of a class of persons who acquired Edison International common stock between March 21, 2014 and June 24, 2015 (the "Class Period"). In September 2016 , the federal court granted defendants' motion to dismiss the complaint, with an opportunity for plaintiff to amend the complaint. Plaintiff filed an amended complaint, which the federal court dismissed again with an opportunity for the plaintiff to amend the complaint. Plaintiff filed a third amended complaint and defendants again moved to dismiss the complaint in October 2016 . Also in July 2015 , a federal shareholder derivative lawsuit was filed against members of the Edison International Board of Directors for breach of fiduciary duty and other claims. The federal derivative lawsuit is based on similar allegations to the federal class action securities lawsuit and seeks monetary damages, including punitive damages, and various corporate governance reforms. An additional federal shareholder derivative lawsuit making essentially the same allegations was filed in August 2015 and was subsequently consolidated with the July 2015 federal derivative lawsuit. In September 2016 , the federal court granted defendants' motion to dismiss the consolidated complaint, with an opportunity for plaintiff to amend the complaint. Plaintiff did not file an amended complaint by the required date. Plaintiffs' deadline to appeal the federal court's order granting defendants' motion to dismiss lapsed in March 2017 and no appeal was filed. In October 2015 , a shareholder derivative lawsuit was filed in California state court against members of the Edison International Board of Directors for breach of fiduciary duty and other claims, making similar allegations to those in the federal derivative lawsuits discussed above. In light of the ruling in the parallel federal derivative lawsuit discussed above, plaintiff requested that the court voluntarily dismiss the state court action. The action was dismissed in April 2017 . In November 2015 , a purported securities class action lawsuit was filed in federal court against Edison International, its then Chief Executive Officer and its Treasurer by an Edison International employee, alleging claims under the Employee Retirement Income Security Act. The complaint purports to be filed on behalf of a class of Edison International employees who were participants in the Edison 401(k) Savings Plan and invested in the Edison International Stock Fund between March 27, 2014 and June 24, 2015 . The complaint alleges that defendants breached their fiduciary duties because they knew or should have known that investment in the Edison International Stock Fund was imprudent because the price of Edison International common stock was artificially inflated due to Edison International's alleged failure to disclose certain ex parte communications with CPUC decision-makers related to the San Onofre OII. In July 2016 , the federal court granted the defendants' motion to dismiss the lawsuit with an opportunity for the plaintiff to amend her complaint. Plaintiff filed an amended complaint in July 2016 , that dismissed Edison International as a named defendant and the remaining defendants filed a motion to dismiss in August 2016 . These defendants' motion was heard by the court in November 2016 . In June 2017, the federal court again granted defendants' motion to dismiss the lawsuit with an opportunity for the plaintiff to amend her complaint. Plaintiff filed an amended complaint in early July 2017 . Defendants have filed motion to dismiss the amended complaint, which was heard by the court in October 2017 , and are awaiting a ruling. Edison International and SCE cannot predict the outcome of these proceedings. Environmental Remediation SCE records its environmental remediation liabilities when site assessments and/or remedial actions are probable and a range of reasonably likely cleanup costs can be estimated. SCE reviews its sites and measures the liability quarterly, by assessing a range of reasonably likely costs for each identified site using currently available information, including existing technology, presently enacted laws and regulations, experience gained at similar sites, and the probable level of involvement and financial condition of other potentially responsible parties. These estimates include costs for site investigations, remediation, operation and maintenance, monitoring and site closure. Unless there is a single probable amount, SCE records the lower end of this reasonably likely range of costs (reflected in "Other long-term liabilities") at undiscounted amounts as timing of cash flows is uncertain. At December 31, 2017 , SCE's recorded estimated minimum liability to remediate its 20 identified material sites (sites with a liability balance as of December 31, 2017 , in which the upper end of the range of the costs is at least $1 million ) was $146 million , including $93 million related to San Onofre. In addition to these sites, SCE also has 16 immaterial sites with a liability balance at December 31, 2017 for which the total minimum recorded liability was $4 million . Of the $150 million total environmental remediation liability for SCE, $144 million has been recorded as a regulatory asset. SCE expects to recover $49 million through an incentive mechanism that allows SCE to recover 90% of its environmental remediation costs at certain sites (SCE may request to include additional sites) and $95 million through a mechanism that allows SCE to recover 100% of the costs incurred at certain sites through customer rates. SCE's identified sites include several sites for which there is a lack of currently available information, including the nature and magnitude of contamination, and the extent, if any, that SCE may be held responsible for contributing to any costs incurred for remediating these sites. Thus, no reasonable estimate of cleanup costs can be made for these sites. The ultimate costs to clean up SCE's identified sites may vary from its recorded liability due to numerous uncertainties inherent in the estimation process, such as: the extent and nature of contamination; the scarcity of reliable data for identified sites; the varying costs of alternative cleanup methods; developments resulting from investigatory studies; the possibility of identifying additional sites; and the time periods over which site remediation is expected to occur. SCE believes that, due to these uncertainties, it is reasonably possible that cleanup costs at the identified material sites and immaterial sites could exceed its recorded liability by up to $129 million and $8 million , respectively. The upper limit of this range of costs was estimated using assumptions least favorable to SCE among a range of reasonably possible outcomes. SCE expects to clean up and mitigate its identified sites over a period of up to 30 years . Remediation costs for each of the next 4 years are expected to range from $5 million to $21 million . Costs incurred for years ended December 31, 2017, 2016 and 2015 were $9 million , $4 million and $5 million , respectively. Based upon the CPUC's regulatory treatment of environmental remediation costs incurred at SCE, SCE believes that costs ultimately recorded will not materially affect its results of operations, financial position or cash flows. There can be no assurance, however, that future developments, including additional information about existing sites or the identification of new sites, will not require material revisions to estimates. Nuclear Insurance Federal law limits public offsite liability claims for bodily injury and property damage from a nuclear incident to the amount of available financial protection, which is currently approximately $13.4 billion . As of January 1, 2017, SCE and other owners of San Onofre and Palo Verde have purchased the maximum private primary insurance available ( $450 million ) through a Facility Form issued by American Nuclear Insurers ("ANI"). The balance is covered by a loss sharing program among nuclear reactor licensees. If a nuclear incident at any licensed reactor in the United States results in claims and/or costs which exceed the primary insurance at that plant site, all nucl

Preferred and Preference Stock

Preferred and Preference Stock of Utility	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Preferred and Preference Stock of Utility	Preferred and Preference Stock of Utility SCE's authorized shares are: $100 cumulative preferred – 12 million shares, $25 cumulative preferred – 24 million shares and preference with no par value – 50 million shares. SCE's outstanding shares are not subject to mandatory redemption. There are no dividends in arrears for the preferred or preference shares. Shares of SCE's preferred stock have liquidation and dividend preferences over shares of SCE's common stock and preference stock. All cumulative preferred shares are redeemable. When preferred shares are redeemed, the premiums paid, if any, are charged to common equity. No preferred shares were issued or redeemed in the years ended December 31, 2017 , 2016 and 2015 . There is no sinking fund requirement for redemptions or repurchases of preferred shares. Shares of SCE's preference stock rank junior to all of the preferred stock and senior to all common stock. Shares of SCE's preference stock are not convertible into shares of any other class or series of SCE's capital stock or any other security. There is no sinking fund requirement for redemptions or repurchases of preference shares. Preferred stock and preference stock is: Shares Redemption December 31, (in millions, except shares and per-share amounts) 2017 2016 Cumulative preferred stock $25 par value: 4.08% Series 650,000 $ 25.50 $ 16 $ 16 4.24% Series 1,200,000 25.80 30 30 4.32% Series 1,653,429 28.75 41 41 4.78% Series 1,296,769 25.80 33 33 Preference stock No par value: 6.25% Series E (cumulative) 350,000 1,000.00 350 350 5.625% Series F (cumulative) 190,004 2,500.00 — 475 5.10% Series G (cumulative) 160,004 2,500.00 400 400 5.75% Series H (cumulative) 110,004 2,500.00 275 275 5.375% Series J (cumulative) 130,004 2,500.00 325 325 5.45% Series K (cumulative) 120,004 2,500.00 300 300 5.00% Series L (cumulative) 190,004 2,500.00 475 — SCE's preferred and preference stock 2,245 2,245 Less issuance costs (52 ) (54 ) Edison International's preferred and preference stock of utility $ 2,193 $ 2,191 Shares of Series E preference stock issued in 2012 may be redeemed at par, in whole or in part, on or after February 1, 2022. Shares of Series G, H, J, K and L preference stock, issued in 2013 , 2014 , 2015, 2016 and 2017, respectively, may be redeemed at par, in whole, but not in part, at any time prior to March 15, 2018, March 15, 2024, September 15, 2025, March 15, 2026 and June 26, 2022, respectively, if certain changes in tax or investment company law or interpretation (or applicable rating agency equity credit criteria for Series L only) occur and certain other conditions are satisfied. On or after March 15, 2018, March 15, 2024, September 15, 2025, March 15, 2026 and June 26, 2022, SCE may redeem the Series G, H, J, K and L shares, respectively, at par, in whole or in part. For shares of Series H, J and K preference stock, distributions will accrue and be payable at a floating rate from and including March 15, 2024, September 15, 2025 and March 15, 2026, respectively. Shares of Series G, H, J, K and L preference stock were issued to SCE Trust II, SCE Trust III, SCE Trust IV, SCE Trust V and SCE Trust VI, respectively, special purpose entities formed to issue trust securities as discussed in Note 3. The proceeds from the sale of the shares of Series L were used to redeem $ 475 million of the Company's Series F preference stock. Preference shares are not subject to mandatory redemption. At December 31, 2017 , declared and unpaid dividends related to SCE's preferred and preference stock were $12 million .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The changes in accumulated other comprehensive loss, net of tax, consist of: Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Beginning balance $ (53 ) $ (56 ) $ (20 ) $ (22 ) Pension and PBOP – net gain (loss): Other comprehensive income (loss) before reclassifications 3 (4 ) (2 ) (2 ) Reclassified from accumulated other comprehensive loss 1 7 6 3 3 Other — 1 — 1 Change 10 3 1 2 Ending balance $ (43 ) $ (53 ) $ (19 ) $ (20 ) 1 These items are included in the computation of net periodic pension and PBOP expenses. See Note 8 for additional information.

Interest and Other Income and O

Interest and Other Income and Other Expenses	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Interest and Other Income and Other Expenses	Interest and Other Income and Other Expenses Interest and other income and other expenses are as follows: Years ended December 31, (in millions) 2017 2016 2015 SCE interest and other income: Equity allowance for funds used during construction $ 87 $ 74 $ 87 Increase in cash surrender value of life insurance policies and life insurance benefits 42 39 26 Interest income 7 3 4 Other 9 7 6 Total SCE interest and other income 145 123 123 Other income of Edison International Parent and Other 1 1 — 51 Total Edison International interest and other income $ 146 $ 123 $ 174 SCE other expenses: Civic, political and related activities and donations $ (34 ) $ (32 ) $ (35 ) Other (14 ) (12 ) (24 ) Total SCE other expenses (48 ) (44 ) (59 ) Other expenses of Edison International Parent and Other (3 ) — — Total Edison International other expenses $ (51 ) $ (44 ) $ (59 ) 1 Reflects Edison Capital's income related to the sale of affordable housing projects for the year ended December 31, 2015.

Supplemental Cash Flows Informa

Supplemental Cash Flows Information	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flows Information	Supplemental Cash Flows Information Supplemental cash flows information for continuing operations is: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Cash payments for interest and taxes: Interest, net of amounts capitalized $ 548 $ 504 $ 512 $ 509 $ 475 $ 478 Tax payments, net of refunds 1 18 1 2 78 144 Non-cash financing and investing activities: Dividends declared but not paid: Common stock $ 197 $ 177 $ 156 $ 212 $ — $ — Preferred and preference stock 12 12 14 12 12 14 Details of debt exchange: Pollution-control bonds redeemed (2.875%) — — (203 ) — — (203 ) Pollution-control bonds issued (1.875%) — — 203 — — 203 SCE's accrued capital expenditures at December 31, 2017 , 2016 and 2015 were $652 million , $540 million , and $543 million , respectively. Accrued capital expenditures will be included as an investing activity in the consolidated statements of cash flow in the period paid. During 2015, SCE amended a power contract classified as a capital lease, which resulted in a reduction in the lease obligation and asset by $ 147 million .

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related-Party Transactions Edison International and SCE provide and receive various services to and from its subsidiaries and affiliates. Services provided to Edison International by SCE are priced at fully loaded cost (i.e., direct cost of good or service and allocation of overhead cost). Specified administrative services such as payroll, employee benefit programs, all performed by Edison International or SCE employees, are shared among all affiliates of Edison International. Costs are allocated based on one of the following formulas: percentage of time worked, equity in investment and advances, number of employees, or multi-factor (operating revenue, operating expenses, total assets and number of employees). Edison International allocates various corporate administrative and general costs to SCE and other subsidiaries using established allocation factors.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) Edison International's quarterly financial data is as follows: 2017 (in millions, except per-share amounts) Total Fourth Third Second First Operating revenue $ 12,320 $ 3,220 $ 3,672 $ 2,965 $ 2,463 Operating income (loss) 1,493 (16 ) 561 469 479 Income (loss) from continuing operations 1,2 668 (534 ) 501 309 392 Income (loss) from discontinued operations, net — — — — — Net income (loss) attributable to common shareholders 565 (545 ) 470 278 362 Basic earnings (loss) per share: Continuing operations $ 1.73 $ (1.67 ) $ 1.44 $ 0.85 $ 1.11 Discontinued operations — — — — — Total $ 1.73 $ (1.67 ) $ 1.44 $ 0.85 $ 1.11 Diluted earnings (loss) per share: Continuing operations $ 1.72 $ (1.66 ) $ 1.43 $ 0.85 $ 1.10 Discontinued operations — — — — — Total $ 1.72 $ (1.66 ) $ 1.43 $ 0.85 $ 1.10 Dividends declared per share 2.2325 0.6050 0.5425 0.5425 0.5425 Common stock prices: High $ 83.38 $ 83.38 $ 81.58 $ 82.82 $ 81.33 Low 62.67 62.67 76.38 77.21 70.57 Close 63.24 63.24 77.17 78.19 79.61 1 In the fourth quarter of 2017, Edison International Parent and Other recorded a charge of $433 million related to the re-measurement of deferred taxes as a result of Tax Reform. 2 In the fourth quarter of 2017, SCE recorded impairment and other charges of $716 million ( $448 million after-tax) related to the Revised San Onofre Settlement Agreement. 2016 (in millions, except per-share amounts) Total Fourth Third Second First Operating revenue $ 11,869 $ 2,884 $ 3,767 $ 2,777 $ 2,440 Operating income 2,092 566 695 381 448 Income from continuing operations 1,413 347 451 310 305 Income (loss) from discontinued operations, net 12 13 — (2 ) 1 Net income attributable to common shareholders 1,311 329 421 280 281 Basic earnings (loss) per share: Continuing operations $ 3.99 $ 0.97 $ 1.29 $ 0.87 $ 0.86 Discontinued operations 0.03 0.04 — (0.01 ) — Total $ 4.02 $ 1.01 $ 1.29 $ 0.86 $ 0.86 Diluted earnings (loss) per share: Continuing operations $ 3.94 $ 0.96 $ 1.27 $ 0.86 $ 0.85 Discontinued operations 0.03 0.04 — (0.01 ) — Total $ 3.97 $ 1.00 $ 1.27 $ 0.85 $ 0.85 Dividends declared per share 1.9825 0.5425 0.4800 0.4800 0.4800 Common stock prices: High $ 78.72 $ 73.81 $ 78.72 $ 77.71 $ 72.34 Low 57.97 67.44 71.31 67.71 57.97 Close 71.99 71.99 72.25 77.67 71.89 SCE's quarterly financial data is as follows: 2017 (in millions) Total Fourth Third Second First Operating revenue $ 12,254 $ 3,193 $ 3,652 $ 2,953 $ 2,456 Operating income (loss) 1,598 (4 ) 578 517 507 Net income (loss) 1 1,136 (79 ) 497 338 380 Net income (loss) available for common stock 1,012 (109 ) 465 307 349 Common dividends declared 785 212 191 191 191 1 In the fourth quarter of 2017, SCE recorded impairment and other charges of $716 million ( $448 million after-tax) related to the Revised San Onofre Settlement Agreement. 2016 (in millions) Total Fourth Third Second First Operating revenue $ 11,830 $ 2,874 $ 3,752 $ 2,768 $ 2,435 Operating income 2,217 594 721 429 472 Net income 1,499 359 466 349 325 Net income available for common stock 1,376 328 435 318 295 Common dividends declared 701 191 170 170 170 Due to the seasonal nature of Edison International and SCE's business, a significant amount of revenue and earnings are recorded in the third quarter of each year. As a result of rounding, the total of the four quarters does not always equal the amount for the year.

Schedule I - Condensed Financia

Schedule I - Condensed Financial Information of Parent	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule I - Condensed Financial Information of Parent	EDISON INTERNATIONAL SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT CONDENSED BALANCE SHEETS December 31, (in millions) 2017 2016 Assets: Cash and cash equivalents $ 524 $ 6 Other current assets 340 261 Total current assets 864 267 Investments in subsidiaries 13,659 13,459 Deferred income taxes 500 646 Other long-term assets 91 108 Total assets $ 15,114 $ 14,480 Liabilities and equity: Short-term debt $ 1,139 $ 539 Current portion of long-term debt — 400 Other current liabilities 467 484 Total current liabilities 1,606 1,423 Long-term debt 1,193 397 Other long-term liabilities 644 664 Total equity 11,671 11,996 Total liabilities and equity $ 15,114 $ 14,480 EDISON INTERNATIONAL SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT CONDENSED STATEMENTS OF INCOME For the Years Ended December 31, 2017 , 2016 and 2015 (in millions) 2017 2016 2015 Interest income from affiliates $ — $ 6 $ 3 Operating expenses and interest expense 92 86 78 Loss before equity in earnings of subsidiaries (92 ) (80 ) (75 ) Equity in earnings of subsidiaries 739 1,337 1,025 Income before income taxes 647 1,257 950 Income tax expense (benefit) 82 (42 ) (35 ) Income from continuing operations 565 1,299 985 Income from discontinued operations, net of tax — 12 35 Net income $ 565 $ 1,311 $ 1,020 CONDENSED STATEMENTS OF COMPREHENSIVE INCOME For the Years Ended December 31, 2017 , 2016 and 2015 (in millions) 2017 2016 2015 Net income $ 565 $ 1,311 $ 1,020 Other comprehensive income, net of tax 10 3 2 Comprehensive income $ 575 $ 1,314 $ 1,022 EDISON INTERNATIONAL SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT CONDENSED STATEMENTS OF CASH FLOWS For the Years Ended December 31, 2017 , 2016 and 2015 (in millions) 2017 2016 2015 Net cash provided by operating activities $ 462 $ 493 $ 641 Cash flows from financing activities: Long-term debt issued 798 400 — Long-term debt issuance costs (5 ) (3 ) — Long-term debt matured (400 ) — — Payable due to affiliates 8 34 54 Short-term debt financing, net 600 (108 ) 26 Payments for stock-based compensation (260 ) (95 ) (114 ) Receipts for stock-based compensation 144 51 72 Dividends paid (707 ) (626 ) (544 ) Net cash provided by (used in) financing activities 178 (347 ) (506 ) Capital contributions to affiliate (122 ) (147 ) (30 ) Loans to affiliate — — (106 ) Net cash used in investing activities: (122 ) (147 ) (136 ) Net increase (decrease) in cash and cash equivalents 518 (1 ) (1 ) Cash and cash equivalents, beginning of year 6 7 8 Cash and cash equivalents, end of year $ 524 $ 6 $ 7 Note 1. Basis of Presentation The accompanying condensed financial statements of Edison International Parent should be read in conjunction with the consolidated financial statements and notes thereto of Edison International and subsidiaries ("Registrant") included in this Form 10-K. Edison International's Parent significant accounting policies are consistent with those of the Registrant, SCE and other wholly owned and controlled subsidiaries. Dividends Received Edison International Parent received cash dividends from SCE of $573 million , $701 million and $758 million in 2017 , 2016 and 2015 , respectively. During the fourth quarter of 2017, SCE declared a dividend to Edison International of $212 million , which was paid on January 31, 2018. Dividend Restrictions The CPUC regulates SCE's capital structure which limits the dividends it may pay Edison International. Under CPUC regulations, SCE may make distributions to Edison International as long as the common equity component of SCE's capital structure remains at or above 48% on a 13 -month average basis, or otherwise satisfies the CPUC requirements. If the Revised San Onofre Settlement Agreement is approved by the CPUC, SCE may exclude the $448 million after-tax charge resulting from the implementation of the Revised San Onofre Settlement Agreement from its ratemaking capital structure. At December 31, 2017 , without excluding the $448 million after-tax charge, SCE's 13 -month average common equity component of total capitalization was 50.0% and the maximum additional dividend that SCE could pay to Edison International under this limitation was approximately $511 million , resulting in a restriction on net assets of approximately $14.2 billion . If the Revised San Onofre Settlement Agreement had been approved by the CPUC at December 31, 2017, the common equity component of SCE's capital structure would have been 50.1% on a 13 -month average basis. Note 2. Debt and Credit Agreements Long-Term Debt During the first quarter of 2017, Edison International issued $400 million of 2.125% senior notes due in 2020 . The proceeds were used to repay commercial paper borrowings and for general corporate purposes. In August 2017, Edison International issued $400 million of 2.40% senior notes due in 2022 . In addition, at December 31, 2017 and 2016, respectively, Edison International Parent had $400 million of 2.95% senior notes due in 2023 and $400 million of 3.75% senior notes, which were paid in September 2017 with the proceeds from the August 2017 issuance as discussed above. Credit Agreements and Short-Term Debt The following table summarizes the status of the credit facility at December 31, 2017 : (in millions) Commitment $ 1,250 Outstanding borrowings (1,139 ) Amount available $ 111 During the second quarter of 2017, Edison International Parent amended the credit facility to extend the maturity date for the $1.25 billion credit facility to July 2022. At December 31, 2017 , the outstanding commercial paper, net of discount, was $639 million at a weighted-average interest rate of 1.70% . This commercial paper was supported by the $1.25 billion multi-year revolving credit facility. In December 2017, Edison International Parent borrowed $500 million from the credit facility which had an interest rate of 2.56% on December 31, 2017 . In January 2018, Edison International repaid its $500 million borrowings with cash on hand. At December 31, 2016 , the outstanding commercial paper, net of discount, was $538 million at a weighted-average interest rate of 0.97% . In January 2018, Edison International Parent borrowed $500 million under a Term Loan Agreement due in January 2019, with a variable interest rate based on the London Interbank Offered Rate plus 60 basis points. The proceeds were used to repay Edison International Parent's commercial paper borrowings discussed above. The debt covenant in Edison International's credit facility requires a consolidated debt to total capitalization ratio of less than or equal to 0.65 to 1 . At December 31, 2017 , Edison International's consolidated debt to total capitalization ratio was 0.51 to 1 . Note 3. Related-Party Transactions Edison International's Parent expense from services provided by SCE was $3 million annually in 2017, 2016 and 2015. Edison International's Parent interest expense from loans due to affiliates was $5 million in 2017, $3 million in 2016 and $6 million in 2015. Edison International Parent had current related-party receivables of $256 million and $262 million and current related-party payables of $235 million and $221 million at December 31, 2017 and 2016 , respectively. During 2017, a related-party note receivable of $184 million was converted into a capital contribution. Edison International Parent had long-term related-party receivables of $81 million and $103 million at December 31, 2017 and 2016 , respectively, and long-term related-party payables of $200 million and $243 million at December 31, 2017 and 2016 , respectively. Note 4. Contingencies For a discussion of material contingencies see "Notes to Consolidated Financial Statements—Note 7. Income Taxes" and "—Note 11. Commitments and Contingencies."

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	EDISON INTERNATIONAL SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS Additions (in millions) Balance at Beginning of Period Charged to Costs and Expenses Charged to Other Accounts Deductions Balance at End of Period For the Year ended December 31, 2017 Allowance for uncollectible accounts Customers $ 41.2 $ 12.9 $ — $ 17.5 $ 36.6 All others 20.6 13.5 — 16.8 17.3 Total allowance for uncollectible amounts $ 61.8 $ 26.4 $ — $ 34.3 a $ 53.9 Tax valuation allowance $ 24.0 $ — $ 4.0 c $ — $ 28.0 For the Year ended December 31, 2016 Allowance for uncollectible accounts Customers $ 46.2 $ 17.7 $ — $ 22.7 $ 41.2 All others 15.5 15.9 — 10.8 20.6 Total allowance for uncollectible amounts $ 61.7 $ 33.6 $ — $ 33.5 a $ 61.8 Tax valuation allowance $ 32.0 $ — $ — $ 8.0 b $ 24.0 For the Year ended December 31, 2015 Allowance for uncollectible accounts Customers $ 48.9 $ 23.9 $ — $ 26.6 $ 46.2 All others 23.3 18.0 — 25.8 15.5 Total allowance for uncollectible amounts $ 72.2 $ 41.9 $ — $ 52.4 a $ 61.7 Tax valuation allowance $ 29.0 $ 3.0 $ — $ — $ 32.0 a Accounts written off, net. b In 2016, Edison International determined that $8 million of the assets subject to a valuation allowance had no expectation of recovery and were written off. c As a result of Tax Reform, Edison International recorded an additional valuation allowance of $4 million for non-California state net operating loss carryforwards estimated to expire unused. SOUTHERN CALIFORNIA EDISON COMPANY SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS Additions (in millions) Balance at Beginning of Period Charged to Costs and Expenses Charged to Other Accounts Deductions Balance at End of Period For the Year ended December 31, 2017 For the Year ended Customers $ 40.5 $ 12.9 $ — $ 17.4 $ 36.0 All others 20.6 13.5 — 16.8 17.3 Total allowance for uncollectible accounts $ 61.1 $ 26.4 $ — $ 34.2 a $ 53.3 For the Year ended December 31, 2016 Allowance for uncollectible accounts Customers $ 46.2 $ 17.0 $ — $ 22.7 $ 40.5 All others 15.5 15.9 — 10.8 20.6 Total allowance for uncollectible accounts $ 61.7 $ 32.9 $ — $ 33.5 a $ 61.1 For the Year ended December 31, 2015 Allowance for uncollectible accounts Customers $ 48.9 $ 23.9 $ — $ 26.6 $ 46.2 All others 18.7 18.0 — 21.2 15.5 Total allowance for uncollectible accounts $ 67.6 $ 41.9 $ — $ 47.8 a $ 61.7 a Accounts written off, net.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Edison International is the parent holding company of Southern California Edison Company ("SCE") and Edison Energy Group, Inc. ("Edison Energy Group"). SCE is an investor-owned public utility primarily engaged in the business of supplying and delivering electricity to an approximately 50,000 square mile area of southern California. Edison Energy Group is a holding company for subsidiaries, including Edison Energy, LLC ("Edison Energy") and SoCore Energy LLC ("SoCore Energy"), engaged in pursuing competitive business opportunities across energy services, managed portfolio solutions, and distributed solar solutions for commercial and industrial customers. Such business activities are currently not material to report as a separate business segment. These combined notes to the consolidated financial statements apply to both Edison International and SCE unless otherwise described. Edison International's consolidated financial statements include the accounts of Edison International, SCE and other wholly owned and controlled subsidiaries. References to Edison International refer to the consolidated group of Edison International and its subsidiaries. References to Edison International Parent and Other refer to Edison International Parent and its competitive subsidiaries. SCE's consolidated financial statements include the accounts of SCE and its wholly owned and controlled subsidiaries. All intercompany transactions have been eliminated from the consolidated financial statements. Edison International's and SCE's accounting policies conform to accounting principles generally accepted in the United States of America, including the accounting principles for rate-regulated enterprises, which reflect the ratemaking policies of the California Public Utility Commission ("CPUC") and the Federal Energy Regulatory Commission ("FERC"). SCE applies authoritative guidance for rate-regulated enterprises to the portion of its operations in which regulators set rates at levels intended to recover the estimated costs of providing service, plus a return on net investments in assets, or rate base. Regulators may also impose certain penalties or grant certain incentives. Due to timing and other differences in the collection of electric utility revenue, these principles require an incurred cost that would otherwise be charged to expense by a non-regulated entity to be capitalized as a regulatory asset if it is probable that the cost is recoverable through future rates; and conversely the principles require recording of a regulatory liability for amounts collected in rates to recover costs expected to be incurred in the future or amounts collected in excess of costs incurred and refundable to customers. In addition, SCE recognizes revenue and regulatory assets from alternative revenue programs, which enables the utility to adjust future rates in response to past activities or completed events, if certain criteria are met, even for programs that do not qualify for recognition of "traditional" regulatory assets and liabilities. SCE assesses, at the end of each reporting period, whether regulatory assets are probable of future recovery. See Note 10 for composition of regulatory assets and liabilities.
Use of Estimates	The preparation of financial statements in conformity with United States generally accepted accounting principles ("GAAP") requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reported period. Actual results could differ from those estimates.
Cash Equivalents and Restricted Cash	Cash Equivalents Cash equivalents includes investments in money market funds. Generally, the carrying value of cash equivalents equals the fair value, as these investments have original maturities of three months or less. The cash equivalents were as follows: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Money market funds $ 1,024 $ 41 $ 483 $ 18 Cash is temporarily invested until required for check clearing. Checks issued, but not yet paid by the financial institution, are reclassified from cash to accounts payable at the end of each reporting period as follows: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Book balances reclassified to accounts payable $ 64 $ 138 $ 63 $ 136 Restricted Cash Edison International's restricted cash at December 31, 2017 and 2016 were $41 million and $18 million , respectively. Restricted cash primarily relates to funds held by SoCore Energy and its consolidated affiliates pursuant to project financing or purchase agreements; most of which are expected to lapse by the end of 2018 .
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts Allowances for uncollectible accounts are provided based upon a variety of factors, including historical amounts written-off, current economic conditions and assessment of customer collectability.
Inventory	Inventory SCE's inventory is primarily composed of materials, supplies and spare parts, and generally stated at average cost.
Emission Allowances	Emission Allowances SCE is allocated greenhouse gas ("GHG") allowances annually which it is then required to sell into quarterly auctions. GHG proceeds from the auctions are recorded as a regulatory liability to be refunded to customers. SCE purchases GHG allowances in quarterly auctions or from counterparties to satisfy its GHG emission compliance obligations and recovers such costs of GHG allowances from customers. GHG allowances held for use are classified as "Other current assets" on the consolidated balance sheets and are stated, similar to an inventory method, at the lower of weighted-average cost or market.
Property, Plant and Equipment	Property, Plant and Equipment SCE plant additions, including replacements and betterments, are capitalized. Direct material and labor and indirect costs such as construction overhead, administrative and general costs, pension and benefits, and property taxes are capitalized as part of plant additions. The CPUC authorizes a capitalization rate for each of the indirect costs which are allocated to each project based on either labor or total costs. Estimated useful lives (authorized by the CPUC) and weighted-average useful lives of SCE's property, plant and equipment, are as follows: Estimated Useful Lives Weighted-Average Useful Lives Generation plant 10 years to 55 years 37 years Distribution plant 20 years to 60 years 43 years Transmission plant 40 years to 65 years 52 years General plant and other 5 years to 60 years 22 years Depreciation of utility property, plant and equipment is computed on a straight-line, remaining-life basis. Depreciation expense was $1.61 billion , $1.52 billion and $1.42 billion for 2017 , 2016 and 2015 , respectively. Depreciation expense stated as a percent of average original cost of depreciable utility plant was, on a composite basis, 3.8% , 3.8% and 3.9% for 2017 , 2016 and 2015 , respectively. The original costs of retired property is charged to accumulated depreciation. Nuclear fuel for the Palo Verde Nuclear Generating Station ("Palo Verde") is recorded as utility plant (nuclear fuel in the fabrication and installation phase is recorded as construction in progress) in accordance with CPUC ratemaking procedures. Palo Verde nuclear fuel is amortized using the units of production method. Allowance for funds used during construction ("AFUDC") represents the estimated cost of debt and equity funds that finance utility-plant construction and is capitalized during certain plant construction. AFUDC is recovered in rates through depreciation expense over the useful life of the related asset. AFUDC equity represents a method to compensate SCE for the estimated cost of equity used to finance utility plant additions and is recorded as part of construction in progress. AFUDC equity was $87 million , $74 million and $87 million in 2017 , 2016 and 2015 , respectively, and is reflected in "Interest and other income." AFUDC debt was $28 million , $23 million and $31 million in 2017 , 2016 and 2015 , respectively and is reflected as a reduction of "Interest expense." Major Maintenance Major maintenance costs for SCE's power plant facilities and equipment are expensed as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Impairments of long-lived assets are evaluated based on a review of estimated future cash flows expected to be generated whenever events or changes in circumstances indicate that the carrying amount of such investments or assets may not be recoverable. If the carrying amount of a long-lived asset exceeds expected future cash flows, undiscounted and without interest charges, an impairment loss is recognized in the amount of the excess of fair value over the carrying amount. Fair value is determined via market, cost and income based valuation techniques, as appropriate.
Goodwill	Goodwill Edison International assesses goodwill through annual goodwill impairment tests, at the reporting unit level as of October 1st of each year. Edison International will update these tests between annual tests if events occur or circumstances change such that it is more likely than not that the fair value of a reporting unit is below its carrying value. During 2017, Edison International completed a strategic review of Edison Energy Group's competitive businesses. Edison International has concluded that it will evaluate strategic options, including potential sale opportunities, for SoCore Energy. In connection with the strategic review of the Edison Energy Group's competitive businesses, Edison International evaluated the recoverability of goodwill and recorded an impairment of SoCore Energy's goodwill totaling $16.5 million ( $10 million after-tax) in the second quarter of 2017. The fair value of the Edison Energy and SoCore Energy reporting units exceeded their carrying values at the date of the impairment analysis. As of December 31, 2017 and 2016, goodwill is comprised of $78 million at each year end at the Edison Energy reporting unit and $5 million and $22 million , respectively, at the SoCore Energy reporting unit.
Nuclear Decommissioning and Asset Retirement Obligations	Nuclear Decommissioning and Asset Retirement Obligations The fair value of a liability for an asset retirement obligation ("ARO") is recorded in the period in which it is incurred, including a liability for the fair value of a conditional ARO, if the fair value can be reasonably estimated even though uncertainty exists about the timing and/or method of settlement. When an ARO liability is initially recorded, SCE capitalizes the cost by increasing the carrying amount of the related long-lived asset. For each subsequent period, the liability is increased for accretion expense and the capitalized cost is depreciated over the useful life of the related asset. AROs related to decommissioning of SCE's nuclear power facilities are based on site-specific studies conducted as part of each Nuclear Decommissioning Cost Triennial Proceeding ("NDCTP") conducted before the CPUC. Revisions of an ARO are established for updated site-specific decommissioning cost estimates. SCE adjusts its nuclear decommissioning obligation into a nuclear-related ARO regulatory asset and also records an ARO regulatory liability as a result of timing differences between the recognition of costs and the recovery of costs through the ratemaking process. For further information, see Notes 9 and 10. SCE has not recorded an asset retirement obligation for assets that are expected to operate indefinitely or where SCE cannot estimate a settlement date (or range of potential settlement dates). As such, ARO liabilities are not recorded for certain retirement activities, including certain hydroelectric facilities. The following table summarizes the changes in SCE's ARO liability, including San Onofre Nuclear Generating Station ("San Onofre") and Palo Verde: December 31, (in millions) 2017 2016 Beginning balance $ 2,586 $ 2,762 Accretion 1 166 157 Revisions 376 (165 ) Liabilities settled (236 ) (168 ) Ending balance $ 2,892 $ 2,586 1 An ARO represents the present value of a future obligation. Accretion is an increase in the liability to account for the time value of money resulting from discounting. The recorded liability to decommission SCE's nuclear power facilities (included in the table above) is $2.6 billion as of December 31, 2017. In 2016, SCE updated the recorded liability for Palo Verde and San Onofre Unit 1 based on the 2013 decommissioning study performed for Palo Verde and the 2014 study for San Onofre Unit 1. In 2017, SCE further revised the recorded liability for Palo Verde and San Onofre Units 2 and 3 based on updated cost estimates, including changes related to onboarding the general contractor. The final site specific study for San Onofre Units 2 and 3 is expected to be filed in March 2018 as part of the 2018 NDCTP which may result in additional changes to the ARO estimate. Decommissioning costs, which are recovered through customer rates over the term of each nuclear facility's operating license, are recorded as a component of depreciation expense, with a corresponding credit to the ARO regulatory liability. Amortization of the ARO asset (included within the unamortized nuclear investment) and accretion of the ARO liability are deferred as increases to the ARO regulatory liability account, resulting in no impact on earnings. SCE has collected in rates amounts for the future decommissioning of its nuclear assets, and has placed those amounts in independent trusts. Amounts collected in rates in excess of the ARO liability are classified as regulatory liabilities. Changes in the estimated costs, timing of decommissioning or the assumptions underlying these estimates could cause material revisions to the estimated total cost to decommission. SCE currently estimates that it will spend approximately $7.2 billion through 2079 to decommission its nuclear facilities. This estimate is based on SCE's decommissioning cost methodology used for ratemaking purposes, escalated at rates ranging from 1.6% to 7.5% (depending on the cost element) annually. These costs are expected to be funded from independent decommissioning trusts. SCE estimates annual after-tax earnings on the decommissioning funds of 2.4% to 3.8% . Future decommissioning costs related to SCE's nuclear assets are expected to be funded from independent decommissioning trusts. If the assumed return on trust assets is not earned or costs escalate at higher rates, SCE expects that additional funds needed for decommissioning will be recoverable through future rates. See Note 9 for further information. Due to regulatory recovery of SCE's nuclear decommissioning expense, prudently incurred costs for nuclear decommissioning activities do not affect SCE's earnings. SCE's nuclear decommissioning costs are subject to CPUC review through the triennial regulatory proceeding. SCE's nuclear decommissioning trust investments primarily consist of fixed income and equity investments that are classified as available-for-sale. Due to regulatory mechanisms, earnings and realized gains and losses (including other-than-temporary impairments) have no impact on earnings. Unrealized gains and losses on decommissioning trust funds increase or decrease the trust assets and the related regulatory asset or liability and have no impact on electric utility revenue or decommissioning expense. SCE reviews each security for other-than-temporary impairment on the last day of each month. If the fair value on the last day of two consecutive months is less than the cost for that security, SCE recognizes a loss for the other-than-temporary impairment. If the fair value is greater or less than the carrying value for that security at the time of sale, SCE recognizes a related realized gain or loss, respectively.
Deferred Financing Costs	Deferred Financing Costs Debt premium, discount and issuance expenses incurred in connection with obtaining financing are deferred and amortized on a straight-line basis. Under CPUC ratemaking procedures, SCE's debt reacquisition expenses are amortized over the remaining life of the reacquired debt or, if refinanced, the life of the new debt.
Revenue Recognition	Revenue Recognition Revenue is recognized when electricity is delivered and includes amounts for services rendered but unbilled at the end of each reporting period as reflected in "Operating revenue" on the consolidated statements of income. Rates charged to customers are based on CPUC- and FERC-authorized revenue requirements. CPUC rates are implemented subsequent to final approval. CPUC rates decouple authorized revenue from the volume of electricity sales. Differences between amounts collected and authorized levels are either collected from or refunded to customers, and therefore, SCE earns revenue equal to amounts authorized. FERC rates also decouple revenue from volume of electricity sales. In November 2013, the FERC approved a formula rate effective January 1, 2012 to determine SCE's FERC transmission revenue requirement, including its construction work in progress ("CWIP") revenue requirement. Under operation of the formula rate, transmission revenue will be updated to actual cost of service annually. Differences between amounts collected and determined under the formula rate are either collected from or refunded to customers, and therefore, SCE earns revenue based on estimates of recorded rate base costs under the FERC formula rate. SCE bills certain sales and use taxes levied by state or local governments to its customers. Included in these sales and use taxes are franchise fees, which SCE pays to various municipalities (based on contracts with these municipalities) in order to operate within the limits of the municipality. SCE bills these franchise fees to its customers based on a CPUC-authorized rate. These franchise fees, which are required to be paid regardless of SCE's ability to collect from the customer, are accounted for on a gross basis and reflected in electric utility revenue and other operation and maintenance expense.
Power Purchase Agreements	Power Purchase Agreements SCE enters into power purchase agreements in the normal course of business. A power purchase agreement may be considered a variable interest in a variable interest entity ("VIE"). If SCE is the primary beneficiary in the VIE, SCE should consolidate the VIE. None of SCE's power purchase agreements resulted in consolidation of a VIE at December 31, 2017 and 2016 . See Note 3 for further discussion of power purchase agreements that are considered variable interests. A power purchase agreement may also contain a lease for accounting purposes. This generally occurs when a power purchase agreement designates a specific power plant in which the buyer purchases substantially all of the output and does not otherwise meet a fixed price per unit of output exception. SCE has a number of power purchase agreements that contain leases. SCE's recognition of lease expense conforms to the ratemaking treatment for SCE's recovery of the cost of electricity and is recorded in "Purchased power and fuel" on the consolidated statements of income. See Note 11 for further discussion of SCE's power purchase agreements, including agreements that are classified as operating and capital leases for accounting purposes. A power purchase agreement that does not contain a lease may be classified as a derivative which is recorded at fair value on the consolidated balance sheets. These power purchase agreements may be eligible for an election to designate as a normal purchase and sale, which is accounted for on an accrual basis as an executory contract. See Note 6 for further information on derivative instruments. Power purchase agreements that do not meet the above classifications are accounted for on an accrual basis.
Derivatives Instruments	Derivative Instruments SCE records derivative instruments on its consolidated balance sheets as either assets or liabilities measured at fair value unless otherwise exempted from derivative treatment as normal purchases or sales. The normal purchases and sales exception requires, among other things, physical delivery in quantities expected to be used or sold over a reasonable period in the normal course of business. During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms. Realized gains and losses from SCE's derivative instruments are expected to be recovered from or refunded to customers through regulatory mechanisms and, therefore, SCE's fair value changes have no impact on purchased-power expense or earnings. SCE does not use hedge accounting for derivative transactions due to regulatory accounting treatment. Where SCE's derivative instruments are subject to a master netting agreement and certain criteria are met, SCE presents its derivative assets and liabilities on a net basis on its consolidated balance sheets. In addition, derivative positions are offset against margin and cash collateral deposits. The results of derivative activities are recorded as part of cash flows from operating activities on the consolidated statements of cash flows. See Note 6 for further information on derivative instruments.
Leases	Leases SCE enters into power purchase agreements that may contain leases, as discussed under "Power Purchase Agreements" above. SCE also enters into a number of agreements to lease property and equipment in the normal course of business. Minimum lease payments under SCE's operating leases for property and equipment are reflected in "Operation and maintenance" on the consolidated statements of income.
Stock-Based Compensation	Stock-Based Compensation Stock options, performance shares, deferred stock units and restricted stock units have been granted under Edison International's long-term incentive compensation programs. Generally, Edison International does not issue new common stock for settlement of equity awards, which are recorded as part of retained earnings. Rather, a third party is used to purchase shares from the market and deliver such shares for the settlement of option exercises, performance shares, deferred stock units and restricted stock units. The performance shares awarded that are earned are settled solely in cash. Deferred stock units and restricted stock units are settled in common stock; however, Edison International will substitute cash awards to the extent necessary to pay tax withholding or any government levies. Stock-based compensation expense is recognized on a straight-line basis over the requisite service period and is based on the number of awards that are expected to vest. Edison International and SCE estimate the number of awards that are expected to vest rather than account for forfeitures when they occur. For awards granted to retirement-eligible participants, stock compensation expenses are recognized on a prorated basis over the initial year. For awards granted to participants who become eligible for retirement during the requisite service period, stock compensation expenses are recognized over the period between the date of grant and the date the participant first becomes eligible for retirement. Under new accounting guidance adopted in 2016, share-based payments may create a permanent difference between the amount of compensation expense recognized for book and tax purposes. The tax impact of this permanent difference is recognized in earnings in the period it is created.
SCE Dividend Restrictions	SCE Dividend Restrictions The CPUC regulates SCE's capital structure which limits the dividends it may pay Edison International. Under CPUC regulations, SCE may make distributions to Edison International as long as the common equity component of SCE's capital structure remains at or above 48% on a 13 -month average basis, or otherwise satisfies the CPUC requirements.
Earnings Per Share	Earnings Per Share Edison International computes earnings per common share ("EPS") using the two-class method, which is an earnings allocation formula that determines EPS for each class of common stock and participating security. Edison International's participating securities are stock-based compensation awards payable in common shares, including performance shares and restricted stock units, which earn dividend equivalents on an equal basis with common shares once the awards are vested. Performance shares awarded prior to 2015 that are earned are settled half in common shares and half in cash, while the performance shares awarded on or after 2015 that are earned are settled solely in cash. For further information, see Note 8.
Income Taxes	Income Taxes Edison International and SCE estimate their income taxes for each jurisdiction in which they operate. This involves estimating current period tax expense along with assessing temporary differences resulting from differing treatment of items (such as depreciation) for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included in the consolidated balance sheets. In December 2017, the Tax Cuts and Jobs Act ("Tax Reform") was signed into law. This comprehensive reform of tax law reduces the federal corporate income tax rate from 35% to 21% which resulted in the re-measurement of deferred taxes using the new tax rate. See Note 7 for further information. Income tax expense includes the current tax liability from operations and the change in deferred income taxes during the year. Investment tax credits are deferred and amortized to income tax expense over the lives of the properties or the term of the power purchase agreement of the respective project. Interest income, interest expense and penalties associated with income taxes are reflected in "Income tax expense" on the consolidated statements of income. Edison International's eligible subsidiaries are included in Edison International's consolidated federal income tax and combined state tax returns. Edison International has tax-allocation and payment agreements with certain of its subsidiaries. Pursuant to an income tax-allocation agreement approved by the CPUC, SCE's tax liability is computed as if it filed its federal and state income tax returns on a separate return basis.
Redeemable Noncontrolling Interest	Noncontrolling Interest Noncontrolling interest represents the portion of equity ownership in an entity that is not attributable to the equity holders of Edison International. Noncontrolling interests held by third parties that have rights to put their ownership back to a subsidiary of Edison International are classified outside shareholders' equity as redeemable noncontrolling interest. Noncontrolling interest is initially recorded at fair value and is subsequently adjusted for income allocated to the noncontrolling interest and any distributions paid to the noncontrolling interest.
New Accounting Guidance	New Accounting Guidance Accounting Guidance Not Yet Adopted In May 2014, the FASB issued an accounting standards update on revenue recognition and further amended the standard in 2016 and 2017. Under the new standard, revenue from contracts with customers is recognized when (or as) a good or service is transferred to the customer and the customer obtains control of the good or service. For the year ended December 31, 2017, approximately 95% of total operating revenue arises from SCE's tariff offerings that provide electricity to customers. For such arrangements, revenue from contracts with customers will be equivalent to the electricity supplied and billed in that period (including estimated billings). As such, there will not be a change in the timing or pattern of revenue recognition for such sales. Edison International and SCE have implemented process changes necessary to comply with this standard's enhanced disclosure requirements. SCE will disaggregate customer contract revenue between revenue from earnings activities and revenue from cost-recovery activities. Some revenue arrangements, such as alternative revenue programs which include balancing account overcollections and undercollections, are excluded from the scope of the new standard and, therefore, will be accounted for and presented separately from revenue recognized from contracts with customers in the disclosures. Edison International and SCE will adopt the standard by using the modified retrospective method. Edison International will recognize an immaterial cumulative effect adjustment to the opening balance of retained earnings on January 1, 2018. In January 2016, the FASB issued an accounting standards update that amends the guidance on the classification and measurement of financial instruments. The amendments require equity investments (excluding those accounted for under the equity method or those that result in consolidation) to be measured at fair value, with changes in fair value through net income. It also amends certain disclosure requirements associated with the fair value of financial instruments. In addition, the new guidance requires financial assets and financial liabilities to be presented separately in the notes to the financial statements, grouped by measurement category and form of financial assets. Edison International and SCE will adopt this guidance effective January 1, 2018. SCE's nuclear decommissioning trust investments contain equity investments that are classified as available-for-sale. Due to regulatory mechanisms, the change in fair value of these investments has no impact on net income and, therefore, the adoption of this standard will not have a material impact on Edison International's and SCE's consolidated financial statements. In February 2016, the FASB issued an accounting standards update related to lease accounting, effective January 1, 2019. Under the new standard, a lease is defined as a contract, or part of a contract, that conveys the right to control the use of identified assets for a period of time in exchange for consideration. Lessees will need to recognize leases on the balance sheet as a right-of-use asset and a related lease liability, and classify the leases as either operating or finance. The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustments, such as initial direct costs. Edison International operating leases will result in straight-line expense while finance leases will result in a higher initial expense pattern due to the interest component. SCE, as a regulated entity, is permitted to continue to recognize expense using the timing that conforms to the regulatory rate treatment. Lessees can elect to exclude from the balance sheet short-term contracts of one year or less. The standard requires retrospective application to previously issued financial statements for 2018 and 2017. Although permitted, Edison and SCE will not elect to adopt this standard prior to January 1, 2019. The standard will provide entities with an optional transition method to apply the new requirements in the period of adoption without retrospective application to previous periods. Edison International and SCE are evaluating whether to elect this optional transition method. The adoption of this standard will increase right-of-use assets and lease liabilities in Edison International's and SCE's consolidated balance sheets. Edison International and SCE are currently implementing a new lease accounting system and are evaluating the impact this standard will have on the consolidated balance sheets and lease disclosures. The FASB issued an accounting standards update related to the impairment of financial instruments, effective January 1, 2020. The new guidance provides an impairment model, known as the current expected credit loss model, which is based on expected credit losses rather than incurred losses. Edison International and SCE are currently evaluating the impact of this new guidance. The FASB issued two accounting standards updates related to the statement of cash flows. One standards update clarifies the presentation and classification of certain cash receipts and payments in the statement of cash flows and the other requires restricted cash to be presented with cash and cash equivalents in the statement of cash flows. These standards are effective January 1, 2018 and require retrospective application. Restricted cash as of December 31, 2017 was $41 million at Edison International and was less than $1 million at SCE. Currently, the changes in restricted cash balances are reflected as operating or investing activities dependent on the nature of the activities. In January 2017, the FASB issued an accounting standards update to simplify the accounting for goodwill impairment. This accounting standards update changes the procedural steps in applying the goodwill impairment test. A goodwill impairment will now be the amount by which a reporting unit's carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Edison International will apply this guidance to the goodwill impairment test beginning in 2020. In March 2017, the FASB issued an accounting standards update which amends the current requirements related to the presentation of the components of net periodic benefit cost for an entity's defined benefit pension and other postretirement plans. The adoption of this standard is not expected to have a material impact on Edison International's and SCE's financial position or results of operations, but will result in the separate presentation of service costs as an operating expense and non-service costs within other income and expense and limit the capitalization of benefit costs to the service cost component. For the year ended December 31, 2017, service costs totaled $169 million for Edison International and $164 million for SCE and the non-service component of net periodic benefit cost was income of $72 million for Edison International and $84 million for SCE. The new standards update is effective on January 1, 2018 and is required to be adopted retrospectively with respect to the income statement presentation requirement and prospectively for the capitalization requirement.

Summary of Significant Accoun30

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Cash Equivalents	The cash equivalents were as follows: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Money market funds $ 1,024 $ 41 $ 483 $ 18 Cash is temporarily invested until required for check clearing. Checks issued, but not yet paid by the financial institution, are reclassified from cash to accounts payable at the end of each reporting period as follows: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Book balances reclassified to accounts payable $ 64 $ 138 $ 63 $ 136
Estimated Useful Lives (Authorized by the CPUC) and Weighted-Average Useful Lives of Property, Plant and Equipment	Estimated useful lives (authorized by the CPUC) and weighted-average useful lives of SCE's property, plant and equipment, are as follows: Estimated Useful Lives Weighted-Average Useful Lives Generation plant 10 years to 55 years 37 years Distribution plant 20 years to 60 years 43 years Transmission plant 40 years to 65 years 52 years General plant and other 5 years to 60 years 22 years
Reconciliation of the Changes in ARO Liability	The following table summarizes the changes in SCE's ARO liability, including San Onofre Nuclear Generating Station ("San Onofre") and Palo Verde: December 31, (in millions) 2017 2016 Beginning balance $ 2,586 $ 2,762 Accretion 1 166 157 Revisions 376 (165 ) Liabilities settled (236 ) (168 ) Ending balance $ 2,892 $ 2,586 1 An ARO represents the present value of a future obligation. Accretion is an increase in the liability to account for the time value of money resulting from discounting.
Amortization of Deferred Financing Costs	Amortization of deferred financing costs charged to interest expense is as follows: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Amortization of deferred financing costs charged to interest expense $ 30 $ 31 $ 33 $ 27 $ 27 $ 28
EPS Attributable to Edison International Common Shareholders	EPS attributable to Edison International common shareholders was computed as follows: Years ended December 31, (in millions, except per-share amounts) 2017 2016 2015 Basic earnings per share – continuing operations: Income from continuing operations attributable to common shareholders $ 565 $ 1,299 $ 985 Participating securities dividends — — (1 ) Income from continuing operations available to common shareholders $ 565 $ 1,299 $ 984 Weighted average common shares outstanding 326 326 326 Basic earnings per share – continuing operations $ 1.73 $ 3.99 $ 3.02 Diluted earnings per share – continuing operations: Income from continuing operations attributable to common shareholders $ 565 $ 1,299 $ 985 Participating securities dividends — — (1 ) Income from continuing operations available to common shareholders $ 565 $ 1,299 $ 984 Income impact of assumed conversions — 1 1 Income from continuing operations available to common shareholders and assumed conversions $ 565 $ 1,300 $ 985 Weighted average common shares outstanding 326 326 326 Incremental shares from assumed conversions 2 4 3 Adjusted weighted average shares – diluted 328 330 329 Diluted earnings per share – continuing operations $ 1.72 $ 3.94 $ 2.99

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant, and Equipment	SCE's property, plant and equipment included in the consolidated balance sheets is composed of the following: December 31, (in millions) 2017 2016 Distribution $ 23,633 $ 22,332 Transmission 13,127 12,549 Generation 3,468 3,376 General plant and other 4,534 4,633 Accumulated depreciation (9,355 ) (9,000 ) 35,407 33,890 Construction work in progress 3,175 2,790 Nuclear fuel, at amortized cost 126 126 Total utility property, plant and equipment $ 38,708 $ 36,806
Schedule of Jointly Owned Utility Projects	The following is SCE's investment in each asset as of December 31, 2017 : (in millions) Plant in Service Construction Work in Progress Accumulated Depreciation Nuclear Fuel (at amortized cost) Net Book Value Ownership Interest Transmission systems: Eldorado $ 237 $ 14 $ 24 $ — $ 227 59 % Pacific Intertie 192 41 78 — 155 50 % Generating station: Palo Verde (nuclear) 2,001 52 1,557 126 622 16 % Total $ 2,430 $ 107 $ 1,659 $ 126 $ 1,004

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2017
Variable Interest Entities Disclosure [Abstract]
Variable Interest Entity, Condensed Income Statement	The following table provides a summary of the trusts' income statements: Years ended December 31, (in millions) Trust I Trust II Trust III Trust IV Trust V Trust VI 2017 Dividend income $ 14 $ 20 $ 16 $ 17 $ 16 $ 12 Dividend distributions 14 20 16 17 16 12 2016 Dividend income $ 27 $ 20 $ 16 $ 17 $ 13 * Dividend distributions 27 20 16 17 13 * 2015 Dividend income $ 27 $ 20 $ 16 $ 6 * * Dividend distributions 27 20 16 6 * * * Not applicable

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amounts and Fair Values of Long-term Debt, Including Current Portion	The carrying value and fair value of Edison International's and SCE's long-term debt (including current portion of long-term debt) are as follows: December 31, 2017 December 31, 2016 (in millions) Carrying Value 1 Fair Value Carrying Value 1 Fair Value Edison International $ 12,123 $ 13,760 $ 11,156 $ 12,368 SCE 10,907 12,547 10,333 11,539 1 Carrying value is net of debt issuance costs.
SCE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value by Level	The following table sets forth assets and liabilities of SCE that were accounted for at fair value by level within the fair value hierarchy: December 31, 2017 (in millions) Level 1 Level 2 Level 3 Netting and Collateral 1 Total Assets at fair value Derivative contracts $ — $ 9 $ 102 $ (1 ) $ 110 Money market funds and other 495 — — — 495 Nuclear decommissioning trusts: Stocks 2 1,596 — — — 1,596 Fixed Income 3 1,065 1,665 — — 2,730 Short-term investments, primarily cash equivalents 101 72 — — 173 Subtotal of nuclear decommissioning trusts 4 2,762 1,737 — — 4,499 Total assets 3,257 1,746 102 (1 ) 5,104 Liabilities at fair value Derivative contracts — 2 1 (2 ) 1 Total liabilities — 2 1 (2 ) 1 Net assets $ 3,257 $ 1,744 $ 101 $ 1 $ 5,103 December 31, 2016 (in millions) Level 1 Level 2 Level 3 Netting and Collateral 1 Total Assets at fair value Derivative contracts $ — $ 6 $ 68 $ — $ 74 Other 33 — — — 33 Nuclear decommissioning trusts: Stocks 2 1,547 — — — 1,547 Fixed Income 3 865 1,751 — — 2,616 Short-term investments, primarily cash equivalents 36 170 — — 206 Subtotal of nuclear decommissioning trusts 4 2,448 1,921 — — 4,369 Total assets 2,481 1,927 68 — 4,476 Liabilities at fair value Derivative contracts — — 1,157 — 1,157 Total liabilities — — 1,157 — 1,157 Net assets (liabilities) $ 2,481 $ 1,927 $ (1,089 ) $ — $ 3,319 1 Represents the netting of assets and liabilities under master netting agreements and cash collateral across the levels of the fair value hierarchy. Netting among positions classified within the same level is included in that level. 2 Approximately 69% and 70% of SCE's equity investments were located in the United States at December 31, 2017 and 2016 , respectively. 3 Includes corporate bonds, which were diversified and included collateralized mortgage obligations and other asset backed securities of $102 million and $79 million at December 31, 2017 and 2016 , respectively. 4 Excludes net payables of $59 million and $127 million at December 31, 2017 and 2016 , which consist of interest and dividend receivables as well as receivables and payables related to SCE's pending securities sales and purchases.
Summary of Changes in Fair Value of Level 3 Net Derivative Assets and Liabilities	The following table sets forth a summary of changes in SCE's fair value of Level 3 net derivative assets and liabilities: December 31, (in millions) 2017 2016 Fair value of net liabilities at beginning of period $ (1,089 ) $ (1,148 ) Total realized/unrealized gains: Included in regulatory assets and liabilities 1 133 59 Contract amendment 2 143 — Normal purchase and normal sale designation 3 914 — Fair value of net assets (liabilities) at end of period $ 101 $ (1,089 ) Change during the period in unrealized gains and losses related to assets and liabilities held at the end of the period $ 100 $ (70 ) 1 Due to regulatory mechanisms, SCE's realized and unrealized gains and losses are recorded as regulatory assets and liabilities. 2 Represents a tolling contract that was amended during the second quarter of 2017, which is no longer accounted for as a derivative as of December 31, 2017. 3 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms.
Valuation Techniques and Significant Unobservable Inputs Used to Determine Fair Value for Level 3 Assets and Liabilities	The following table sets forth SCE's valuation techniques and significant unobservable inputs used to determine fair value for significant Level 3 assets and liabilities: Fair Value (in millions) Significant Assets Liabilities Valuation Technique(s) Unobservable Input Range Congestion revenue rights December 31, 2017 $ 102 $ — Market simulation model and auction prices Load forecast 5,002 MW - 22,970 MW Power prices 1 $(15.00) - $120.00 Gas prices 2 $2.46 - $4.37 CAISO CRR auction clearing prices $(9.41) - $8.66 December 31, 2016 67 — Market simulation model and auction prices Load forecast 3,708 MW - 22,840 MW Power prices 1 $3.65 - $99.58 Gas prices 2 $2.51 - $4.87 Tolling 3 December 31, 2016 — 1,154 Option model Volatility of gas prices 15% - 48% Volatility of power prices 29% - 71% Power prices $23.40 - $51.24 1 Prices are in dollars per megawatt-hour. 2 Prices are in dollars per million British thermal units. 3 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms.

Debt and Credit Agreements (Tab

Debt and Credit Agreements (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-term Debt	The following table summarizes long-term debt (rates and terms are as of December 31, 2017 ) of Edison International and SCE: December 31, (in millions) 2017 2016 Edison International Parent and Other: Debentures and notes: 2020 – 2023 (2.125% to 2.95%) $ 1,200 $ 800 Other long-term debt 29 32 Current portion of long-term debt (2 ) (402 ) Unamortized debt discount and issuance costs, net (13 ) (9 ) Total Edison International Parent and Other 1,214 421 SCE: First and refunding mortgage bonds: 2018 – 2047 (1.845% to 6.05%) 9,779 9,357 Pollution-control bonds: 2028 – 2035 (1.375% to 5.0%) 1 909 774 Debentures and notes: 2029 – 2053 (5.06% to 6.65%) 307 307 Current portion of long-term debt (479 ) (579 ) Unamortized debt discount and issuance costs, net (88 ) (105 ) Total SCE 10,428 9,754 Total Edison International $ 11,642 $ 10,175 1 Excludes outstanding bonds that have not been retired and may be remarketed to investors in the future. These bonds have variable rates and are due in 2031 at December 31, 2017 and 2031 and 2033 at December 31, 2016.
Long-term Debt Maturities	Edison International and SCE long-term debt maturities over the next five years are the following: (in millions) Edison International SCE 2018 $ 481 $ 479 2019 81 79 2020 481 79 2021 580 579 2022 777 364
Summary for Status of Credit Facilities	The following table summarizes the status of the credit facilities at December 31, 2017 : (in millions) Edison International Parent SCE Commitment $ 1,250 $ 2,750 Outstanding borrowings (1,139 ) (1,238 ) Outstanding letters of credit — (99 ) Amount available $ 111 $ 1,413

Derivative Instruments (Tables)

Derivative Instruments (Tables) - SCE	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Schedule of Derivative Liabilities in Statement of Financial Position, Fair Value	The following table summarizes the gross and net fair values of SCE's commodity derivative instruments: December 31, 2017 Derivative Assets Derivative Liabilities Net Asset (in millions) Short-Term Long-Term Subtotal Short-Term Long-Term Subtotal 2 Commodity derivative contracts Gross amounts recognized $ 106 $ 5 $ 111 $ 3 $ — $ 3 $ 108 Gross amounts offset in the consolidated balance sheets (1 ) — (1 ) (1 ) — (1 ) — Cash collateral posted 1 — — — (1 ) — (1 ) 1 Net amounts presented in the consolidated balance sheets $ 105 $ 5 $ 110 $ 1 $ — $ 1 $ 109 December 31, 2016 Derivative Assets Derivative Liabilities Net Liability (in millions) Short-Term Long-Term Subtotal Short-Term Long-Term Subtotal Commodity derivative contracts Gross amounts recognized $ 74 $ 1 $ 75 $ 217 $ 941 $ 1,158 $ 1,083 Gross amounts offset in the consolidated balance sheets (1 ) — (1 ) (1 ) — (1 ) — Cash collateral posted 1 — — — — — — — Net amounts presented in the consolidated balance sheets $ 73 $ 1 $ 74 $ 216 $ 941 $ 1,157 $ 1,083 1 At December 31, 2016 , SCE had received $2 million of cash collateral that is not offset against derivative assets and is reflected in "Other current liabilities" on the consolidated balance sheets. 2 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms.
Schedule of Derivative Assets in Statement of Financial Position, Fair Value	The following table summarizes the gross and net fair values of SCE's commodity derivative instruments: December 31, 2017 Derivative Assets Derivative Liabilities Net Asset (in millions) Short-Term Long-Term Subtotal Short-Term Long-Term Subtotal 2 Commodity derivative contracts Gross amounts recognized $ 106 $ 5 $ 111 $ 3 $ — $ 3 $ 108 Gross amounts offset in the consolidated balance sheets (1 ) — (1 ) (1 ) — (1 ) — Cash collateral posted 1 — — — (1 ) — (1 ) 1 Net amounts presented in the consolidated balance sheets $ 105 $ 5 $ 110 $ 1 $ — $ 1 $ 109 December 31, 2016 Derivative Assets Derivative Liabilities Net Liability (in millions) Short-Term Long-Term Subtotal Short-Term Long-Term Subtotal Commodity derivative contracts Gross amounts recognized $ 74 $ 1 $ 75 $ 217 $ 941 $ 1,158 $ 1,083 Gross amounts offset in the consolidated balance sheets (1 ) — (1 ) (1 ) — (1 ) — Cash collateral posted 1 — — — — — — — Net amounts presented in the consolidated balance sheets $ 73 $ 1 $ 74 $ 216 $ 941 $ 1,157 $ 1,083 1 At December 31, 2016 , SCE had received $2 million of cash collateral that is not offset against derivative assets and is reflected in "Other current liabilities" on the consolidated balance sheets. 2 During the third quarter of 2017, SCE designated certain derivative contracts as normal purchase and normal sale contracts, which resulted in a reclassification of $914 million from derivative liabilities to other liabilities. These liabilities will be amortized over the remaining contract terms.
Components of Economic Hedging Activity	The following table summarizes the components of SCE's economic hedging activity: Years ended December 31, (in millions) 2017 2016 2015 Realized losses $ (14 ) $ (59 ) $ (148 ) Unrealized gains (losses) 106 84 (182 )
Notional Volumes of Derivative Instruments	The following table summarizes the notional volumes of derivatives used for SCE hedging activities: Economic Hedges Unit of December 31, Commodity Measure 2017 2016 Electricity options, swaps and forwards GWh 475 1,816 Natural gas options, swaps and forwards Bcf 143 36 Congestion revenue rights GWh 78,765 93,319 Tolling arrangements GWh — 61,093

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Sources of Income (Loss) Before Income Taxes	Edison International's sources of income before income taxes are: Years ended December 31, (in millions) 2017 2016 2015 Income from continuing operations before income taxes $ 949 $ 1,590 $ 1,568 Income from discontinued operations before income taxes — 1 15 Income before income tax $ 949 $ 1,591 $ 1,583
Components of Income Tax Expense (Benefit) by Location of Taxing Jurisdiction	The components of income tax expense (benefit) by location of taxing jurisdiction are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Current: Federal $ (221 ) $ (46 ) $ 18 $ (253 ) $ 75 $ 72 State 4 33 19 (81 ) 93 127 (217 ) (13 ) 37 (334 ) 168 199 Deferred: Federal 570 176 340 265 112 298 State (72 ) 14 109 39 (24 ) 10 498 190 449 304 88 308 Total continuing operations 281 177 486 (30 ) 256 507 Discontinued operations — (11 ) (21 ) — — — Total $ 281 $ 166 $ 465 $ (30 ) $ 256 $ 507
Components of Net Accumulated Deferred Income Tax Liability	The components of net accumulated deferred income tax liability are: Edison International SCE December 31, (in millions) 2017 2016 2017 2016 Deferred tax assets: Property and software related $ 358 $ 549 $ 357 $ 548 Nuclear decommissioning trust assets in excess of nuclear ARO liability 404 348 404 348 Loss and credit carryforwards 1 1,346 1,418 150 — Regulatory asset 2 812 15 812 15 Pension and postretirement benefits other than pensions 214 300 86 93 Other 277 419 236 408 Sub-total 3,411 3,049 2,045 1,412 Less valuation allowance 28 24 — — Total 3,383 3,025 2,045 1,412 Deferred tax liabilities: Property-related 6,970 10,330 6,962 10,330 Capitalized software costs 160 237 160 237 Regulatory liability 158 134 158 134 Nuclear decommissioning trust assets 404 348 404 348 Postretirement benefits other than pensions 36 13 36 13 Other 140 202 133 148 Total 7,868 11,264 7,853 11,210 Accumulated deferred income tax liability, net 3 $ 4,485 $ 8,239 $ 5,808 $ 9,798 1 As of December 31, 2017, Edison International has recorded a valuation allowance of $28 million for non-California state net operating loss carryforwards estimated to expire unused. In addition, as of December 31, 2017, deferred tax assets for net operating loss and tax credit carryforwards are reduced by unrecognized tax benefits of $77 million and $75 million for Edison International and SCE, respectively. 2 Includes an $809 million deferred tax asset, related to certain regulatory liabilities established as part of Tax Reform discussed below. 3 Included in deferred income taxes and credits on the consolidated balance sheets.
Summary of Net Operating Loss and Tax Credit Carryforwards	The amounts of net operating loss and tax credit carryforwards (after-tax) are as follows: Edison International SCE December 31, 2017 (in millions) Loss Carryforwards Credit Carryforwards Loss Carryforwards Credit Carryforwards Expire between 2018 to 2036 $ 901 $ 451 $ 162 $ 25 No expiration date — 71 — 38 Total 1 $ 901 $ 522 $ 162 $ 63
Reconciliation of Income Tax Expense	The table below provides a reconciliation of income tax expense computed at the federal statutory income tax rate to the income tax provision: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Income from continuing operations before income taxes $ 949 $ 1,590 $ 1,568 $ 1,106 $ 1,755 $ 1,618 Provision for income tax at federal statutory rate of 35% 332 556 549 387 614 566 Increase in income tax from: Items presented with related state income tax, net: Regulatory asset write-off 1 — — 382 — — 382 State tax, net of federal benefit 2 29 5 8 43 34 Property-related 2 (439 ) (362 ) (341 ) (439 ) (362 ) (341 ) Change related to uncertain tax positions (18 ) (4 ) (67 ) (13 ) (8 ) (94 ) Revised San Onofre Settlement Agreement 3 25 — — 25 — — Share-based compensation 4 (55 ) (28 ) — (11 ) (13 ) — Deferred tax re-measurement 5 466 — — 33 — — Other (32 ) (14 ) (42 ) (20 ) (18 ) (40 ) Total income tax expense (income)from continuing operations $ 281 $ 177 $ 486 $ (30 ) $ 256 $ 507 Effective tax rate 29.6 % 11.1 % 31.0 % (2.7 )% 14.6 % 31.3 % 1 Includes federal and state. 2 Includes incremental repair benefits. See discussion of repair deductions below. In addition, during 2017, SCE recorded $80 million ( $135 million pre-tax) of tax benefits related to tax accounting method changes resulting from the filing of SCE's 2016 tax returns. 3 Includes the write-off of an unrecovered tax regulatory asset related to the Revised San Onofre Settlement Agreement. See Note 11 for further information. 4 Includes state taxes of $(11) million and $(2) million for Edison International and SCE, respectively, for the year ended December 31, 2017. Includes state taxes of $(4) million and $(1) million for Edison International and SCE, respectively, for the year ended December 31, 2016. Refer to Note 1 for further information. 5 In 2017, Edison International and SCE recorded a charge to earnings related to the re-measurement of deferred taxes resulting from Tax Reform. See further discussion above.
Reconciliation of Unrecognized Tax Benefits	The following table provides a reconciliation of unrecognized tax benefits for continuing and discontinued operations: Edison International SCE December 31, (in millions) 2017 2016 2015 2017 2016 2015 Balance at January 1, $ 471 $ 529 $ 576 $ 371 $ 353 $ 441 Tax positions taken during the current year: Increases 51 36 54 51 36 48 Tax positions taken during a prior year: Increases — 2 66 — — 23 Decreases 1 (7 ) (96 ) (165 ) (13 ) (18 ) (159 ) Decreases for settlements during the period 2 (83 ) — (2 ) (78 ) — — Balance at December 31, $ 432 $ 471 $ 529 $ 331 $ 371 $ 353 1 Decreases in prior year tax positions for 2016 relate to state tax receivables on various claims. Due to the tax risks associated with these claims, the tax benefits were fully reserved at the time the asset was recorded. During 2016, the Company has determined that it will not recognize these assets so the tax benefit and related tax reserve were written off. Decreases in tax positions for 2015 relate primarily to re-measurement of uncertain tax positions in connection with receipt of the Internal Revenue Service ("IRS") Revenue Agent Report in June 2015. See discussions in Tax Disputes below. 2 In the first quarter of 2017, Edison International settled all open tax positions with the IRS for taxable years 2007 through 2012.
Schedule of Interest and Penalties Related to Income Tax Liabilities	The total amount of accrued interest and penalties related to income tax liabilities for continuing and discontinued operations are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Accrued interest and penalties $ 115 $ 128 $ 41 $ 41 The net after-tax interest and penalties recognized in income tax expense for continuing and discontinued operations are: Edison International SCE December 31, (in millions) 2017 2016 2015 2017 2016 2015 Net after-tax interest and penalties tax expense (benefit) $ 6 $ 6 $ (9 ) $ 4 $ 2 $ (14 )

Compensation and Benefit Plans

Compensation and Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Pension and Other Postretirement Benefits
Employee Savings Plan Employer Contributions	The following employer contributions were made for continuing operations: Edison International SCE (in millions) Years ended December 31, 2017 $ 70 $ 69 2016 69 68 2015 73 72
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	The following table summarizes total expense and tax benefits (expense) associated with stock based compensation: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Stock-based compensation expense 1 : Stock options $ 14 $ 14 $ 14 $ 8 $ 7 $ 8 Performance shares 2 13 7 2 6 4 Restricted stock units 6 6 7 3 3 4 Other 1 1 1 — — — Total stock-based compensation expense $ 23 $ 34 $ 29 $ 13 $ 16 $ 16 Income tax benefits related to stock compensation expense 2 $ 72 $ 41 $ 12 $ 15 $ 20 $ 7 Excess tax benefits 2 — — 15 — — 23 1 Reflected in "Operation and maintenance" on Edison International's and SCE's consolidated statements of income. 2 Under new accounting guidance adopted in 2016, share-based payments may create a permanent difference between the amount of compensation expense recognized for book and tax purposes. Beginning January 1, 2016, the excess tax impact of this permanent difference is recognized in earnings in the period it is created.
Black-Sholes Option-Pricing Model Assumptions	The Black-Scholes option-pricing model requires various assumptions noted in the following table: Years ended December 31, 2017 2016 2015 Expected terms (in years) 5.7 5.9 5.9 Risk-free interest rate 2.1% - 2.3% 1.2% – 2.2% 1.6% – 2.1% Expected dividend yield 2.7% - 3.8% 2.5% – 3.0% 2.6% – 3.2% Weighted-average expected dividend yield 2.7% 2.9% 2.6% Expected volatility 17.8% - 20.9% 17.2% – 17.5% 16.4% – 17.0% Weighted-average volatility 17.9% 17.4% 16.5%
Summary of Stock Options Activity	The following is a summary of the status of Edison International's stock options: Weighted-Average Stock options Exercise Price Remaining Contractual Term (Years) Aggregate Intrinsic Value (in millions) Edison International: Outstanding at December 31, 2016 11,544,501 $ 50.26 Granted 1,359,599 79.23 Expired — — Forfeited (163,449 ) 69.76 Exercised (4,918,086 ) 43.77 Outstanding at December 31, 2017 7,822,565 58.98 6.37 Vested and expected to vest at December 31, 2017 7,740,798 58.81 6.35 $ 62 Exercisable at December 31, 2017 4,241,658 $ 50.48 5.09 $ 58 SCE: Outstanding at December 31, 2016 4,727,416 $ 51.81 Granted 699,538 79.12 Expired — — Forfeited (77,165 ) 66.27 Exercised (987,161 ) 48.63 Transfers, net 83,074 46.47 Outstanding at December 31, 2017 4,445,702 56.46 5.99 Vested and expected to vest at December 31, 2017 4,402,254 56.28 5.96 $ 45 Exercisable at December 31, 2017 2,555,160 $ 46.94 4.52 $ 43
Schedule of Unrecognized Compensation Expense	At December 31, 2017 , total unrecognized compensation cost related to stock options and the weighted-average period the cost is expected to be recognized are as follows: (in millions) Edison International SCE Unrecognized compensation cost, net of expected forfeitures $ 13 $ 7 Weighted-average period (in years) 2.4 2.3
Supplemental Data on Stock-based Compensation	Supplemental Data on Stock Options Edison International SCE Years ended December 31, (in millions, except per award amounts) 2017 2016 2015 2017 2016 2015 Stock options: Weighted average grant date fair value per option granted $ 10.65 $ 7.38 $ 7.54 $ 10.63 $ 7.50 $ 7.53 Fair value of options vested 11 11 20 5 5 11 Cash used to purchase shares to settle options 293 220 170 77 118 69 Cash from participants to exercise stock options 167 136 113 48 77 45 Value of options exercised 126 84 57 29 41 24 Tax benefits from options exercised 51 34 23 12 17 10
Summary of Nonvested Share Activity	The following is a summary of the status of Edison International's nonvested performance shares: Shares Weighted-Average Fair Value Edison International: Nonvested at December 31, 2016 207,497 $ 84.30 Granted 81,874 Forfeited (53,002 ) Vested 1 (57,247 ) Nonvested at December 31, 2017 179,122 63.85 SCE: Nonvested at December 31, 2016 96,667 $ 84.25 Granted 42,569 Forfeited (25,061 ) Vested 1 (26,427 ) Affiliate transfers, net 974 Nonvested at December 31, 2017 88,722 64.01 1 Relates to performance shares that will be paid in 2018 as performance targets were met at December 31, 2017 .
Summary of Nonvested Restricted Stock Units Activity	The following is a summary of the status of Edison International's nonvested restricted stock units: Edison International SCE Restricted Stock Units Weighted-Average Grant Date Fair Value Restricted Stock Units Weighted-Average Grant Date Fair Value Nonvested at December 31, 2016 345,395 $ 61.05 160,788 $ 60.80 Granted 91,528 79.23 47,100 79.12 Forfeited (7,311 ) 71.16 (3,903 ) 67.65 Vested (126,561 ) 51.08 (64,266 ) 53.64 Affiliate transfers, net — — 1,699 60.35 Nonvested at December 31, 2017 303,051 69.52 141,418 69.96
Pension Plans
Pension and Other Postretirement Benefits
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan	Information on pension plan assets and benefit obligations for continuing and discontinued operations is shown below. Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Change in projected benefit obligation Projected benefit obligation at beginning of year $ 4,284 $ 4,374 $ 3,791 $ 3,878 Service cost 137 139 129 132 Interest cost 164 171 144 150 Actuarial gain (46 ) (125 ) (74 ) (140 ) Benefits paid (360 ) (275 ) (288 ) (229 ) Projected benefit obligation at end of year $ 4,179 $ 4,284 $ 3,702 $ 3,791 Change in plan assets Fair value of plan assets at beginning of year $ 3,388 $ 3,298 $ 3,172 $ 3,080 Actual return on plan assets 483 262 442 239 Employer contributions 105 103 64 82 Benefits paid (360 ) (275 ) (288 ) (229 ) Fair value of plan assets at end of year $ 3,616 $ 3,388 $ 3,390 $ 3,172 Funded status at end of year $ (563 ) $ (896 ) $ (312 ) $ (619 ) Amounts recognized in the consolidated balance sheets consist of 1 : Long-term assets $ 7 $ 2 $ — $ — Current liabilities (17 ) (50 ) (4 ) (4 ) Long-term liabilities (553 ) (848 ) (308 ) (615 ) $ (563 ) $ (896 ) $ (312 ) $ (619 ) Amounts recognized in accumulated other comprehensive loss consist of: Prior service cost $ (1 ) $ (1 ) $ — $ — Net loss 1 77 93 21 24 $ 76 $ 92 $ 21 $ 24 Amounts recognized as a regulatory asset $ 271 $ 574 $ 271 $ 574 Total not yet recognized as expense $ 347 $ 666 $ 292 $ 598 Accumulated benefit obligation at end of year $ 4,022 $ 4,138 $ 3,585 $ 3,683 Pension plans with an accumulated benefit obligation in excess of plan assets: Projected benefit obligation $ 4,179 $ 4,284 $ 3,702 $ 3,791 Accumulated benefit obligation 4,022 4,138 3,585 3,683 Fair value of plan assets 3,616 3,388 3,390 3,172 Weighted-average assumptions used to determine obligations at end of year: Discount rate 3.46 % 3.94 % 3.46 % 3.94 % Rate of compensation increase 4.10 % 4.00 % 4.10 % 4.00 % 1 The SCE liability excludes a long-term payable due to Edison International Parent of $114 million and $124 million at December 31, 2017 and 2016 , respectively, related to certain SCE postretirement benefit obligations transferred to Edison International Parent. SCE's accumulated other comprehensive loss of $21 million and $24 million at December 31, 2017 and 2016 , respectively, excludes net loss of $19 million and $20 million related to these benefits.
Expense Components for Plans	pension expense components for continuing operations are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Service cost $ 138 $ 139 $ 142 $ 133 $ 136 $ 139 Interest cost 164 172 170 149 156 155 Expected return on plan assets (212 ) (220 ) (233 ) (199 ) (205 ) (217 ) Settlement costs 1 6 — — — — — Amortization of prior service cost 3 4 5 3 4 5 Amortization of net loss 2 21 27 40 17 23 35 Expense under accounting standards 120 122 124 103 114 117 Regulatory adjustment (deferred) (28 ) (21 ) (6 ) (28 ) (21 ) (6 ) Total expense recognized $ 92 $ 101 $ 118 $ 75 $ 93 $ 111 1 Under GAAP, a settlement is recorded when lump-sum payments exceed estimated annual service and interest costs. Lump sum payments made in 2017 to Edison International executives retiring in 2016 from the Executive Retirement Plan exceeded the estimated service and interest costs, resulting in a partial settlement of that plan. A settlement loss of approximately $6.4 million ( $3.8 million after-tax) was recorded at Edison International for the year ended December 31, 2017. 2 Includes the amount of net loss reclassified from other comprehensive loss. The amount reclassified for Edison International was $10 million , $10 million and $14 million for the years ended December 31, 2017, 2016 and 2015, respectively. The amount reclassified for SCE was $6 million , $6 million and $8 million , respectively, for the years ended December 31, 2017, 2016 and 2015, respectively.
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income	Other changes in pension plan assets and benefit obligations recognized in other comprehensive loss for continuing operations: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Net loss (gain) $ — $ 6 $ 7 $ 3 $ 4 $ (9 ) Settlement charges (6 ) — — — — — Amortization of net loss (10 ) (10 ) (15 ) (6 ) (6 ) (9 ) Total recognized in other comprehensive loss $ (16 ) $ (4 ) $ (8 ) $ (3 ) $ (2 ) $ (18 ) Total recognized in expense and other comprehensive loss $ 76 $ 97 $ 110 $ 72 $ 91 $ 93
Schedule of Amounts in Accumulated Other Comprehensive Loss to be Recognized	The estimated pension amounts that will be amortized to expense in 2018 for continuing operations are as follows: (in millions) Edison International SCE Unrecognized net loss to be amortized 1 $ 8 $ 6 Unrecognized prior service cost to be amortized 3 3 1 The amount of net loss expected to be reclassified from other comprehensive loss for Edison International's continuing operations and SCE is $8 million and $6 million , respectively.
Schedule of Assumptions Used	Edison International and SCE used the following weighted-average assumptions to determine pension expense for continuing operations: Years ended December 31, 2017 2016 2015 Discount rate 3.94 % 4.18 % 3.85 % Rate of compensation increase 4.00 % 4.00 % 4.00 % Expected long-term return on plan assets 6.50 % 7.00 % 7.00 %
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, are expected to be paid: Edison International SCE (in millions) Years ended December 31, 2018 $ 338 $ 304 2019 343 303 2020 327 293 2021 324 287 2022 309 281 2023 – 2027 1,453 1,299
Postretirement Benefits Other than Pension Plan Assets by Hierarchy Levels	The following table sets forth the Master Trust investments for Edison International and SCE that were accounted for at fair value as of December 31, 2017 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 184 $ 507 $ — $ — $ 691 Corporate stocks 3 718 11 — — 729 Corporate bonds 4 — 676 — — 676 Common/collective funds 5 — — — 705 705 Partnerships/joint ventures 6 — — — 396 396 Other investment entities 7 — — — 262 262 Registered investment companies 8 140 — — — 140 Interest-bearing cash 9 — — — 9 Other — 106 — — 106 Total $ 1,051 $ 1,300 $ — $ 1,363 $ 3,714 Receivables and payables, net (98 ) Net plan assets available for benefits $ 3,616 SCE's share of net plan assets $ 3,390 The following table sets forth the Master Trust investments that were accounted for at fair value as of December 31, 2016 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 217 $ 309 $ — $ — $ 526 Corporate stocks 3 720 15 — — 735 Corporate bonds 4 — 725 — — 725 Common/collective funds 5 — — — 692 692 Partnerships/joint ventures 6 — — — 333 333 Other investment entities 7 — — — 253 253 Registered investment companies 8 124 — — 6 130 Interest-bearing cash 42 — — — 42 Other — 112 — — 112 Total $ 1,103 $ 1,161 $ — $ 1,284 $ 3,548 Receivables and payables, net (160 ) Net plan assets available for benefits $ 3,388 SCE's share of net plan assets $ 3,172 1 These investments are measured at fair value using the net asset value per share practical expedient and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the net plan assets available for benefits. 2 Level 1 U.S. government and agency securities are U.S. treasury bonds and notes. Level 2 primarily relates to the Federal National Mortgage Association and the Federal Home Loan Mortgage Corporation. 3 Corporate stocks are diversified. At December 31, 2017 and 2016 , respectively, performance for actively managed separate accounts is primarily benchmarked against the Russell Indexes ( 54% ) and ( 62% ) and Morgan Stanley Capital International (MSCI) index ( 46% ) and ( 38% ). 4 Corporate bonds are diversified. At December 31, 2017 and 2016 , respectively, this category includes $65 million and $76 million for collateralized mortgage obligations and other asset backed securities of which $18 million and $27 million are below investment grade. 5 At December 31, 2017 and 2016 , respectively, the common/collective assets were invested in equity index funds that seek to track performance of the Standard and Poor's 500 Index ( 41% and 45% ) and Russell 1000 indexes ( 15% ). At both December 31, 2017 and 2016, 15% of the assets in this category are in index funds which seek to track performance in the MSCI All Country World Index exUS. At December 31, 2017 and 2016, a non-index U.S. equity fund representing 25% and 23% of this category for 2017 and 2016 , respectively, is actively managed. 6 At both December 31, 2017 and 2016 , 55% are invested in private equity funds with investment strategies that include branded consumer products, clean technology and California geographic focus companies. At December 31, 2017 and 2016 , respectively, 23% and 22% are invested in publicly traded fixed income securities, 20% and 18% are invested in a broad range of financial assets in all global markets and 2% and 4% of the remaining partnerships are invested in asset backed securities, including distressed mortgages and commercial and residential loans and debt and equity of banks. 7 Other investment entities were primarily invested in (1) emerging market equity securities, (2) a hedge fund that invests through liquid instruments in a global diversified portfolio of equity, fixed income, interest rate, foreign currency and commodities markets, and (3) domestic mortgage backed securities. 8 Level 1 registered investment companies primarily consisted of a global equity mutual fund which seeks to outperform the MSCI World Total Return Index.
Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan	Information on PBOP Plan assets and benefit obligations is shown below: Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Change in benefit obligation Benefit obligation at beginning of year $ 2,276 $ 2,350 $ 2,266 $ 2,341 Service cost 31 35 31 34 Interest cost 86 97 85 97 Special termination benefits 1 2 1 2 Plan Amendments — (6 ) — (6 ) Actuarial loss (gain) 24 (110 ) 23 (110 ) Plan participants' contributions 24 19 24 19 Benefits paid (105 ) (111 ) (105 ) (111 ) Benefit obligation at end of year $ 2,337 $ 2,276 $ 2,325 $ 2,266 Change in plan assets Fair value of plan assets at beginning of year $ 2,102 $ 2,036 $ 2,102 $ 2,036 Actual return on assets 297 137 297 137 Employer contributions 12 21 12 21 Plan participants' contributions 24 19 24 19 Benefits paid (105 ) (111 ) (105 ) (111 ) Fair value of plan assets at end of year $ 2,330 $ 2,102 $ 2,330 $ 2,102 Funded status at end of year $ (7 ) $ (174 ) $ 5 $ (164 ) Amounts recognized in the consolidated balance sheets consist of: Long-term assets $ 6 $ — $ 17 $ — Current liabilities (13 ) (14 ) (12 ) (13 ) Long-term liabilities — (160 ) — (151 ) $ (7 ) $ (174 ) $ 5 $ (164 ) Amounts recognized in accumulated other comprehensive loss consist of: Net loss $ 4 $ 4 $ — $ — Amounts recognized as a regulatory (liability) asset (26 ) 136 (26 ) 136 Total not yet recognized as (income) expense $ (22 ) $ 140 $ (26 ) $ 136 Weighted-average assumptions used to determine obligations at end of year: Discount rate 3.70 % 4.29 % 3.70 % 4.29 % Assumed health care cost trend rates: Rate assumed for following year 6.75 % 7.00 % 6.75 % 7.00 % Ultimate rate 5.00 % 5.00 % 5.00 % 5.00 % Year ultimate rate reached 2029 2022 2029 2022
Expense Components for Plans	Net periodic PBOP expense components for continuing operations are: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Service cost $ 31 $ 35 $ 46 $ 31 $ 34 $ 46 Interest cost 86 97 102 85 97 102 Expected return on plan assets (110 ) (112 ) (116 ) (110 ) (112 ) (116 ) Special termination benefits 1 1 2 1 1 2 1 Amortization of prior service credit (3 ) (2 ) (12 ) (2 ) (2 ) (12 ) Amortization of net loss — — 3 — — 2 Total expense $ 5 $ 20 $ 24 $ 5 $ 19 $ 23 1 Due to the reduction in workforce, SCE has incurred costs for extended retiree health care coverage.
Schedule of Amounts in Accumulated Other Comprehensive Loss to be Recognized	The estimated PBOP amounts that will be amortized to expense in 2018 for continuing operations are as follows: (in millions) Edison International SCE Unrecognized prior service credit to be amortized $ (1 ) $ (1 )
Schedule of Assumptions Used	Edison International and SCE used the following weighted-average assumptions to determine PBOP expense for continuing operations: Years ended December 31, 2017 2016 2015 Discount rate 4.29 % 4.55 % 4.16 % Expected long-term return on plan assets 5.30 % 5.60 % 5.50 % Assumed health care cost trend rates: Current year 7.00 % 7.50 % 7.75 % Ultimate rate 5.00 % 5.00 % 5.00 % Year ultimate rate reached 2022 2022 2021
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rate	A one-percentage-point change in assumed health care cost trend rate would have the following effects on continuing operations: Edison International SCE (in millions) One-Percentage-Point Increase One-Percentage-Point Decrease One-Percentage-Point Increase One-Percentage-Point Decrease Effect on accumulated benefit obligation as of December 31, 2017 $ 247 $ (203 ) $ 246 $ (202 ) Effect on annual aggregate service and interest costs 9 (8 ) 9 (8 )
Schedule of Expected Benefit Payments	The following benefit payments are expected to be paid: Edison International SCE (in millions) Years ended December 31, 2018 $ 93 $ 93 2019 96 96 2020 100 100 2021 103 103 2022 107 106 2023 – 2027 582 580
Postretirement Benefits Other than Pension Plan Assets by Hierarchy Levels	The following table sets forth the VEBA Trust assets for Edison International and SCE that were accounted for at fair value as of December 31, 2017 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 398 $ 33 $ — $ — $ 431 Corporate stocks 3 254 — — — 254 Corporate notes and bonds 4 — 845 — — 845 Common/collective funds 5 — — — 569 569 Partnerships 6 — — — 82 82 Registered investment companies 7 37 — — — 37 Interest bearing cash 42 — — — 42 Other 8 5 84 — — 89 Total $ 736 $ 962 $ — $ 651 $ 2,349 Receivables and payables, net (19 ) Combined net plan assets available for benefits $ 2,330 The following table sets forth the VEBA Trust assets for SCE that were accounted for at fair value as of December 31, 2016 by asset class and level within the fair value hierarchy: (in millions) Level 1 Level 2 Level 3 NAV 1 Total U.S. government and agency securities 2 $ 222 $ 59 $ — $ — $ 281 Corporate stocks 3 230 — — — 230 Corporate notes and bonds 4 — 877 — — 877 Common/collective funds 5 — — — 462 462 Partnerships 6 — — — 79 79 Registered investment companies 7 48 — — 1 49 Interest bearing cash 48 — — — 48 Other 8 4 103 — — 107 Total $ 552 $ 1,039 $ — $ 542 $ 2,133 Receivables and payables, net (31 ) Combined net plan assets available for benefits $ 2,102 1 These investments are measured at fair value using the net asset value per share practical expedient and have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the net plan assets available for benefits. 2 Level 1 U.S. government and agency securities are U.S. treasury bonds and notes. Level 2 primarily relates to the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association. 3 Corporate stock performance for actively managed separate accounts is primarily benchmarked against the Russell Indexes ( 64% and 47% ) and the MSCI All Country World Index ( 36% and 53% ) for 2017 and 2016 , respectively. 4 Corporate notes and bonds are diversified and include approximately $36 million and $47 million for commercial collateralized mortgage obligations and other asset backed securities at December 31, 2017 and 2016 , respectively. 5 At December 31, 2017 and 2016 , respectively, 75% and 39% of the common/collective assets are invested in index funds which seek to track performance in the MSCI All Country World Index Investable Market Index and MSCI Europe, Australasia and Far East (EAFE) Index. 17% and 18% are invested in a non-index U.S. equity fund which is actively managed. The remaining assets in this category are primarily invested in emerging market fund at December 31, 2017 and a large cap index fund which seeks to track performance of the Russell 1000 index at December 31, 2016 . 6 At December 31, 2017 and 2016 , respectively, 56% and 59% of the partnerships are invested in private equity and venture capital funds. Investment strategies for these funds include branded consumer products, clean and information technology and healthcare. 33% and 31% are invested in a broad range of financial assets in all global markets. 9% of the remaining partnerships category for both years is invested in asset backed securities including distressed mortgages, distressed companies and commercial and residential loans and debt and equity of banks. 7 At December 31, 2017 , registered investment companies were primarily invested in (1) a money market fund, (2) exchange rate trade funds which seek to track performance of MSCI Emerging Market Index, Russell 2000 Index, and international small cap equities. At December 31, 2016 , Level 1 registered investment companies consist of a money market fund. 8 Other includes $60 million and $76 million of municipal securities at December 31, 2017 and 2016 , respectively.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Regulated Entity, Other Assets, Noncurrent [Abstract]
Amortized Cost and Fair Value of the Trust Investments	The following table sets forth amortized cost and fair value of the trust investments (see Note 4 for a discussion of fair value of the trust investments): Longest Maturity Date Amortized Cost Fair Value December 31, (in millions) 2017 2016 2017 2016 Stocks — $ 236 $ 319 $ 1,596 $ 1,547 Municipal bonds 2054 643 659 768 766 U.S. government and agency securities 2067 1,235 1,131 1,319 1,191 Corporate bonds 2057 579 600 643 659 Short-term investments and receivables/payables 1 One-year 110 75 114 79 Total $ 2,803 $ 2,784 $ 4,440 $ 4,242 1 Short-term investments include $29 million and $114 million of repurchase agreements payable by financial institutions which earn interest, are fully secured by U.S. Treasury securities and mature by January 2, 2018 and January 4, 2017 as of December 31, 2017 and 2016 , respectively.

Regulatory Assets and Liabili39

Regulatory Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets Included on the Consolidated Balance Sheets	SCE's regulatory assets included on the consolidated balance sheets are: December 31, (in millions) 2017 2016 Current: Regulatory balancing accounts $ 484 $ 135 Power contracts and energy derivatives 203 150 Unamortized investments, net of accumulated amortization 5 49 Other 11 16 Total current 703 350 Long-term: Deferred income taxes, net of liabilities 3,143 4,478 Pensions and other postretirement benefits 271 710 Power contracts and energy derivatives 799 947 Unamortized investments, net of accumulated amortization 123 80 San Onofre 72 857 Unamortized loss on reacquired debt 168 184 Regulatory balancing accounts 143 66 Environmental remediation 144 126 Other 51 7 Total long-term 4,914 7,455 Total regulatory assets $ 5,617 $ 7,805
Regulatory Liabilities Included on the Consolidated Balance Sheets	SCE's regulatory liabilities included on the consolidated balance sheets are: December 31, (in millions) 2017 2016 Current: Regulatory balancing accounts $ 1,009 $ 736 Energy derivatives 74 — Other 38 20 Total current 1,121 756 Long-term: Costs of removal 2,741 2,847 Re-measurement of deferred taxes 2,892 — Recoveries in excess of ARO liabilities 1,575 1,639 Regulatory balancing accounts 1,316 1,180 Other postretirement benefits 26 — Other 64 60 Total long-term 8,614 5,726 Total regulatory liabilities $ 9,735 $ 6,482
Schedule of Regulatory Balancing Accounts	The following table summarizes the significant components of regulatory balancing accounts included in the above tables of regulatory assets and liabilities: December 31, (in millions) 2017 2016 Asset (liability) Energy resource recovery account $ 464 $ (20 ) New system generation balancing account (197 ) (6 ) Public purpose programs and energy efficiency programs (1,145 ) (992 ) Base revenue requirement balancing account (200 ) (426 ) Tax accounting memorandum account and pole loading balancing account (259 ) (142 ) DOE litigation memorandum account (156 ) (122 ) Greenhouse gas auction revenue (22 ) 31 FERC balancing accounts (205 ) (69 ) Other 22 31 Liability $ (1,698 ) $ (1,715 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Schedule Of Commitments And Contingencies [Line Items]
Summary of Power Purchase Agreements Treated as Operating and Capital Leases	The amount of this discount is shown in the table below as the amount representing interest. (in millions) Operating Leases Capital Leases 2018 $ 335 $ 2 2019 262 2 2020 234 2 2021 198 3 2022 174 3 Thereafter 1,222 21 Total future commitments $ 2,425 $ 33 Amount representing executory costs (15 ) Amount representing interest (8 ) Net commitments $ 10
Summary of Estimated Minimum Future Commitments for Other Operating Leases	The following summarizes the estimated minimum future commitments for SCE's non-cancelable other operating leases (primarily related to vehicles, office space and other equipment): (in millions) Total 2018 $ 48 2019 37 2020 27 2021 20 2022 15 Thereafter 99 Total future commitments $ 246
Schedule of Settlement Agreement	The following table summarizes the financial impact of the Revised San Onofre Settlement Agreement and the Utility Shareholder Agreement: (in millions) San Onofre base regulatory asset $ 696 DOE litigation regulatory liability (72 ) MHI Arbitration regulatory liability (47 ) GHG Reduction Program (10 ) Other 6 Present value of Utility Shareholder Agreement 143 Total pre-tax charge $ 716 Total after-tax charge $ 448
SCE
Schedule Of Commitments And Contingencies [Line Items]
Summary of Undiscounted Future Expected Payments for Power Purchase Agreements That Have Been Approved by the CPUC and Have Completed Major Milestones for Construction	At December 31, 2017 , the undiscounted future expected payments for the SCE power purchase agreements (primarily related to renewable energy contracts), which were approved by the CPUC and met other critical contract provisions (including completion of major milestones for construction), were as follows: (in millions) Total 2018 $ 2,513 2019 2,513 2020 2,614 2021 2,582 2022 2,562 Thereafter 27,093 Total future commitments $ 39,877
Summary of Certain Future Other Commitments	The following summarizes the estimated minimum future commitments for SCE's other commitments: (in millions) 2018 2019 2020 2021 2022 Thereafter Total Other contractual obligations $ 127 $ 72 $ 69 $ 45 $ 46 $ 345 $ 704

Preferred and Preference Stoc41

Preferred and Preference Stock of Utility (Tables)	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Schedule of Stock by Class [Table Text Block]	Preferred stock and preference stock is: Shares Redemption December 31, (in millions, except shares and per-share amounts) 2017 2016 Cumulative preferred stock $25 par value: 4.08% Series 650,000 $ 25.50 $ 16 $ 16 4.24% Series 1,200,000 25.80 30 30 4.32% Series 1,653,429 28.75 41 41 4.78% Series 1,296,769 25.80 33 33 Preference stock No par value: 6.25% Series E (cumulative) 350,000 1,000.00 350 350 5.625% Series F (cumulative) 190,004 2,500.00 — 475 5.10% Series G (cumulative) 160,004 2,500.00 400 400 5.75% Series H (cumulative) 110,004 2,500.00 275 275 5.375% Series J (cumulative) 130,004 2,500.00 325 325 5.45% Series K (cumulative) 120,004 2,500.00 300 300 5.00% Series L (cumulative) 190,004 2,500.00 475 — SCE's preferred and preference stock 2,245 2,245 Less issuance costs (52 ) (54 ) Edison International's preferred and preference stock of utility $ 2,193 $ 2,191

Accumulated Other Comprehensi42

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Components of Accumulated Other Comprehensive Loss	The changes in accumulated other comprehensive loss, net of tax, consist of: Edison International SCE Years ended December 31, (in millions) 2017 2016 2017 2016 Beginning balance $ (53 ) $ (56 ) $ (20 ) $ (22 ) Pension and PBOP – net gain (loss): Other comprehensive income (loss) before reclassifications 3 (4 ) (2 ) (2 ) Reclassified from accumulated other comprehensive loss 1 7 6 3 3 Other — 1 — 1 Change 10 3 1 2 Ending balance $ (43 ) $ (53 ) $ (19 ) $ (20 ) 1 These items are included in the computation of net periodic pension and PBOP expenses. See Note 8 for additional information.

Interest and Other Income and43

Interest and Other Income and Other Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Interest and Other Income and Other Expenses	Interest and other income and other expenses are as follows: Years ended December 31, (in millions) 2017 2016 2015 SCE interest and other income: Equity allowance for funds used during construction $ 87 $ 74 $ 87 Increase in cash surrender value of life insurance policies and life insurance benefits 42 39 26 Interest income 7 3 4 Other 9 7 6 Total SCE interest and other income 145 123 123 Other income of Edison International Parent and Other 1 1 — 51 Total Edison International interest and other income $ 146 $ 123 $ 174 SCE other expenses: Civic, political and related activities and donations $ (34 ) $ (32 ) $ (35 ) Other (14 ) (12 ) (24 ) Total SCE other expenses (48 ) (44 ) (59 ) Other expenses of Edison International Parent and Other (3 ) — — Total Edison International other expenses $ (51 ) $ (44 ) $ (59 ) 1 Reflects Edison Capital's income related to the sale of affordable housing projects for the year ended December 31, 2015.

Supplemental Cash Flows Infor44

Supplemental Cash Flows Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flows Information	Supplemental cash flows information for continuing operations is: Edison International SCE Years ended December 31, (in millions) 2017 2016 2015 2017 2016 2015 Cash payments for interest and taxes: Interest, net of amounts capitalized $ 548 $ 504 $ 512 $ 509 $ 475 $ 478 Tax payments, net of refunds 1 18 1 2 78 144 Non-cash financing and investing activities: Dividends declared but not paid: Common stock $ 197 $ 177 $ 156 $ 212 $ — $ — Preferred and preference stock 12 12 14 12 12 14 Details of debt exchange: Pollution-control bonds redeemed (2.875%) — — (203 ) — — (203 ) Pollution-control bonds issued (1.875%) — — 203 — — 203

Quarterly Financial Data (Una45

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	Edison International's quarterly financial data is as follows: 2017 (in millions, except per-share amounts) Total Fourth Third Second First Operating revenue $ 12,320 $ 3,220 $ 3,672 $ 2,965 $ 2,463 Operating income (loss) 1,493 (16 ) 561 469 479 Income (loss) from continuing operations 1,2 668 (534 ) 501 309 392 Income (loss) from discontinued operations, net — — — — — Net income (loss) attributable to common shareholders 565 (545 ) 470 278 362 Basic earnings (loss) per share: Continuing operations $ 1.73 $ (1.67 ) $ 1.44 $ 0.85 $ 1.11 Discontinued operations — — — — — Total $ 1.73 $ (1.67 ) $ 1.44 $ 0.85 $ 1.11 Diluted earnings (loss) per share: Continuing operations $ 1.72 $ (1.66 ) $ 1.43 $ 0.85 $ 1.10 Discontinued operations — — — — — Total $ 1.72 $ (1.66 ) $ 1.43 $ 0.85 $ 1.10 Dividends declared per share 2.2325 0.6050 0.5425 0.5425 0.5425 Common stock prices: High $ 83.38 $ 83.38 $ 81.58 $ 82.82 $ 81.33 Low 62.67 62.67 76.38 77.21 70.57 Close 63.24 63.24 77.17 78.19 79.61 1 In the fourth quarter of 2017, Edison International Parent and Other recorded a charge of $433 million related to the re-measurement of deferred taxes as a result of Tax Reform. 2 In the fourth quarter of 2017, SCE recorded impairment and other charges of $716 million ( $448 million after-tax) related to the Revised San Onofre Settlement Agreement. 2016 (in millions, except per-share amounts) Total Fourth Third Second First Operating revenue $ 11,869 $ 2,884 $ 3,767 $ 2,777 $ 2,440 Operating income 2,092 566 695 381 448 Income from continuing operations 1,413 347 451 310 305 Income (loss) from discontinued operations, net 12 13 — (2 ) 1 Net income attributable to common shareholders 1,311 329 421 280 281 Basic earnings (loss) per share: Continuing operations $ 3.99 $ 0.97 $ 1.29 $ 0.87 $ 0.86 Discontinued operations 0.03 0.04 — (0.01 ) — Total $ 4.02 $ 1.01 $ 1.29 $ 0.86 $ 0.86 Diluted earnings (loss) per share: Continuing operations $ 3.94 $ 0.96 $ 1.27 $ 0.86 $ 0.85 Discontinued operations 0.03 0.04 — (0.01 ) — Total $ 3.97 $ 1.00 $ 1.27 $ 0.85 $ 0.85 Dividends declared per share 1.9825 0.5425 0.4800 0.4800 0.4800 Common stock prices: High $ 78.72 $ 73.81 $ 78.72 $ 77.71 $ 72.34 Low 57.97 67.44 71.31 67.71 57.97 Close 71.99 71.99 72.25 77.67 71.89 SCE's quarterly financial data is as follows: 2017 (in millions) Total Fourth Third Second First Operating revenue $ 12,254 $ 3,193 $ 3,652 $ 2,953 $ 2,456 Operating income (loss) 1,598 (4 ) 578 517 507 Net income (loss) 1 1,136 (79 ) 497 338 380 Net income (loss) available for common stock 1,012 (109 ) 465 307 349 Common dividends declared 785 212 191 191 191 1 In the fourth quarter of 2017, SCE recorded impairment and other charges of $716 million ( $448 million after-tax) related to the Revised San Onofre Settlement Agreement. 2016 (in millions) Total Fourth Third Second First Operating revenue $ 11,830 $ 2,874 $ 3,752 $ 2,768 $ 2,435 Operating income 2,217 594 721 429 472 Net income 1,499 359 466 349 325 Net income available for common stock 1,376 328 435 318 295 Common dividends declared 701 191 170 170 170

Summary of Significant Accoun46

Summary of Significant Accounting Policies (Organization and Basis of Presentation) (Details) mi² in Thousands	12 Months Ended
	Dec. 31, 2017mi²
Electric Utility | SCE
Segment Reporting Information [Line Items]
Supply Of Electricity Area Covered (in square miles)	50

Summary of Significant Accoun47

Summary of Significant Accounting Policies (Cash Equivalents and Restricted Cash) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents Items [Line Items]
Money market funds	$ 1,024	$ 41
Book balances reclassified to accounts payable	64	138
Restricted cash	41	18
SCE
Cash and Cash Equivalents Items [Line Items]
Money market funds	483	18
Book balances reclassified to accounts payable	63	$ 136
Restricted cash	$ 1

Summary of Significant Accoun48

Summary of Significant Accounting Policies (Emission Allowances) (Details) - SCE - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Current Assets
Significant Accounting Policies [Line Items]
GHG allowances	$ 127	$ 113
Other Current Liabilities
Significant Accounting Policies [Line Items]
GHG emission obligations	$ 129	$ 95

Summary of Significant Accoun49

Summary of Significant Accounting Policies (Property, Plant and Equipment) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 1,610	$ 1,520	$ 1,420
Depreciation expense stated as a percent of average original cost of depreciable utility plant (percent)	3.80%	3.80%	3.90%
AFUDC equity capitalized during construction	$ 87	$ 74	$ 87
Interest and other income
Property, Plant and Equipment [Line Items]
AFUDC equity capitalized during construction	87	74	87
Interest expense
Property, Plant and Equipment [Line Items]
AFUDC debt capitalized during construction	$ 28	$ 23	$ 31
Generation plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	37 years
Distribution plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	43 years
Transmission plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	52 years
General plant and other
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	22 years
Minimum | Generation plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	10 years
Minimum | Distribution plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	20 years
Minimum | Transmission plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	40 years
Minimum | General plant and other
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Maximum | Generation plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	55 years
Maximum | Distribution plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	60 years
Maximum | Transmission plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	65 years
Maximum | General plant and other
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	60 years

Summary of Significant Accoun50

Summary of Significant Accounting Policies (Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
SoCore Energy
Goodwill [Line Items]
Goodwill impairment	$ 16.5
Goodwill impairment after tax	10
Goodwill	5	$ 22
Edison Energy Group
Goodwill [Line Items]
Goodwill	$ 78	$ 78

Summary of Significant Accoun51

Summary of Significant Accounting Policies (Nuclear Decommissioning and Asset Retirement Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation, Roll Forward
Beginning balance	$ 2,590
Ending balance	2,908	$ 2,590
SCE
Asset Retirement Obligation, Roll Forward
Beginning balance	2,586	2,762
Accretion	166	157
Revisions	376	(165)
Liabilities settled	(236)	(168)
Ending balance	$ 2,892	$ 2,586
Threshold period to be recognized as a loss for other-than-temporary impairment	2 months
SCE | Palo Verde and San Onofre Units
Asset Retirement Obligation, Roll Forward
Recorded liability to decommission nuclear power facilities	$ 2,600
Estimated cost to decommission nuclear facilities	$ 7,200
Decommissioning cost escalated rates, low end (percent)	1.60%
Decommissioning cost escalated rates, high end (percent)	7.50%
Estimated annual net of tax earnings, low end (percent)	2.40%
Estimated annual net of tax earnings, high end (percent)	3.80%

Summary of Significant Accoun52

Summary of Significant Accounting Policies (Deferred Financing Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Regulatory assets	$ 4,914	$ 7,455
Edison International
Regulatory Assets [Line Items]
Amortization of deferred financing costs charged to interest expense	30	31	$ 33
Other long-term assets | Edison International
Regulatory Assets [Line Items]
Unamortized debt issuance expense	15	10
Long-term debt | Edison International
Regulatory Assets [Line Items]
Unamortized debt issuance expense	88	81
SCE
Regulatory Assets [Line Items]
Regulatory assets	4,914	7,455
Amortization of deferred financing costs charged to interest expense	27	27	$ 28
SCE | Other long-term assets
Regulatory Assets [Line Items]
Unamortized debt issuance expense	7	7
SCE | Long-term debt
Regulatory Assets [Line Items]
Unamortized debt issuance expense	77	71
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	$ 168	$ 184

Summary of Significant Accoun53

Summary of Significant Accounting Policies (Revenue Recognition) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SCE
Significant Accounting Policies [Line Items]
Franchise fees billed to customers	$ 133	$ 111	$ 138

Summary of Significant Accoun54

Summary of Significant Accounting Policies (Derivative Instruments) (Details) $ in Millions	3 Months Ended
	Sep. 30, 2017USD ($)
SCE
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassified derivative liabilities	$ 914

Summary of Significant Accoun55

Summary of Significant Accounting Policies (SCE Dividend Restrictions) (Details) - SCE $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Significant Accounting Policies [Line Items]
Minimum percentage of weighted-average common equity component authorization, set by CPUC (as a percent)	48.00%
Weighted-average common equity component authorization, set by CPUC remaining over number of months (in months)	13 months
After-tax charge excused from capital structure	$ 448
Period for calculation of weighted average common equity component (months)	13 months
Weighted-average common equity component of total capitalization (as a percent)	50.00%
Capacity to pay additional dividends	$ 511
Restriction on net assets	$ 14,200
Pro forma
Significant Accounting Policies [Line Items]
Weighted-average common equity component authorization, set by CPUC remaining over number of months (in months)	13 months
Period for calculation of weighted average common equity component (months)	13 months
Weighted-average common equity component of total capitalization (as a percent)	50.10%

Summary of Significant Accoun56

Summary of Significant Accounting Policies (Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ 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
Basic earnings per share – continuing operations:
Income from continuing operations, net of tax									$ 565	$ 1,299	$ 985
Participating securities dividends									0	0	(1)
Income from continuing operations available to common shareholders									$ 565	$ 1,299	$ 984
Weighted average common shares outstanding (in shares)									326,000,000	326,000,000	326,000,000
Basic earnings per share – continuing operations (in dollars per share)	$ (1.67)	$ 1.44	$ 0.85	$ 1.11	$ 0.97	$ 1.29	$ 0.87	$ 0.86	$ 1.73	$ 3.99	$ 3.02
Diluted earnings per share – continuing operations:
Income from continuing operations, net of tax									$ 565	$ 1,299	$ 985
Participating securities dividends									0	0	(1)
Income from continuing operations available to common shareholders									565	1,299	984
Income impact of assumed conversions									0	1	1
Income from continuing operations available to common shareholders and assumed conversions									$ 565	$ 1,300	$ 985
Weighted average common shares outstanding (in shares)									326,000,000	326,000,000	326,000,000
Incremental shares from assumed conversions (in shares)									2,000,000	4,000,000	3,000,000
Adjusted weighted average shares - diluted (in shares)									328,000,000	330,000,000	329,000,000
Diluted earnings per share – continuing operations (in dollars per share)	$ (1.66)	$ 1.43	$ 0.85	$ 1.10	$ 0.96	$ 1.27	$ 0.86	$ 0.85	$ 1.72	$ 3.94	$ 2.99
Stock Compensation Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive stock option awards excluded from earnings per share, number of shares									1,334,451	167,795	2,046,045

Summary of Significant Accoun57

Summary of Significant Accounting Policies (Noncontrolling Interest) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Redeemable Noncontrolling Interest [Line Items]
Assets	$ 52,580	$ 51,319
Liabilities	38,695	37,127
Unnamed subsidiary
Redeemable Noncontrolling Interest [Line Items]
Assets	299	74
Liabilities	41	23
Net income	$ 21	$ 9	$ 16

Summary of Significant Accoun58

Summary of Significant Accounting Policies (New Accounting Guidance) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash		$ 41	$ 18
Service cost		169
Non-service costs		72
SCE
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash		1
Service cost		164
Non-service costs		$ 84
SCE | Sales
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales from tariff offerings, percentage of total operating revenues	95.00%

Property, Plant and Equipment59

Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ (9,355)	$ (9,000)
Total utility property, plant and equipment	38,708	36,806
SCE
Property, Plant and Equipment [Line Items]
Distribution	23,633	22,332
Transmission	13,127	12,549
Generation	3,468	3,376
General plant and other	4,534	4,633
Accumulated depreciation	(9,355)	(9,000)
Total utility property, plant and equipment, Gross	35,407	33,890
Construction work in progress	3,175	2,790
Nuclear fuel, at amortized cost	126	126
Total utility property, plant and equipment	$ 38,708	$ 36,806

Property, Plant and Equipment60

Property, Plant and Equipment (Textual) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Capitalized software costs	$ 1,100	$ 1,400
Capitalized software, accumulated amortization	600	800
Capitalized software, amortization expense	233	$ 249	$ 268
Capitalized software, estimated amortization year 1	176
Capitalized software, estimated amortization year 2	127
Capitalized software, estimated amortization year 3	92
Capitalized software, estimated amortization year 4	62
Capitalized software, estimated amortization year 5	$ 26
Capitalized software costs | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Capitalized software costs | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years

Property, Plant and Equipment61

Property, Plant and Equipment (Jointly Owned Utility Projects) (Details) - SCE - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Jointly Owned Utility Plant Interests [Line Items]
Nuclear Fuel (at amortized cost)	$ 126	$ 126
Eldorado
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	237
Construction Work in Progress	14
Accumulated Depreciation	24
Nuclear Fuel (at amortized cost)	0
Net Book Value	$ 227
Ownership Interest (percent)	59.00%
Pacific Intertie
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 192
Construction Work in Progress	41
Accumulated Depreciation	78
Nuclear Fuel (at amortized cost)	0
Net Book Value	$ 155
Ownership Interest (percent)	50.00%
Palo Verde (nuclear)
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 2,001
Construction Work in Progress	52
Accumulated Depreciation	1,557
Nuclear Fuel (at amortized cost)	126
Net Book Value	$ 622
Ownership Interest (percent)	16.00%
Total
Jointly Owned Utility Plant Interests [Line Items]
Plant in Service	$ 2,430
Construction Work in Progress	107
Accumulated Depreciation	1,659
Nuclear Fuel (at amortized cost)	126
Net Book Value	$ 1,004

Variable Interest Entities (Var

Variable Interest Entities (Variable Interest in VIEs that are not Consolidated) (Details)	1 Months Ended	12 Months Ended
	Jul. 31, 2017USD ($)	Dec. 31, 2017USD ($)$ / sharesMW	Dec. 31, 2016USD ($)$ / sharesMW	Dec. 31, 2015USD ($)
Unconsolidated Trust
Stock redeemed		$ 475,000,000	$ 125,000,000	$ 325,000,000
SCE
Unconsolidated Trust
Stock redeemed		$ 475,000,000	$ 125,000,000	$ 325,000,000
SCE | Series F Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.625%
SCE | Series G Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.10%
SCE | Series H Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.75%
SCE | Series J Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.375%
SCE | Series K Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.45%
SCE | Series L Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.00%
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Power Purchase Contracts
Details of projects or entities
Power generating capacity for majority interest (in megawatts) | MW		4,898	4,353
Payments to unconsolidated VIEs for power purchase contracts		$ 767,000,000	$ 788,000,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust I
Unconsolidated Trust
Common stock		$ 10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust I | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.625%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25
Common stock		$ 10,000
Stock redeemed	$ 10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust I | Series F Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.625%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust II
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust II | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.10%
Liquidation preference		$ 400,000,000	$ 400,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust II | Series G Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.10%
Liquidation preference		$ 400,000,000	$ 400,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust III
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust III | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.75%
Liquidation preference		$ 275,000,000	$ 275,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust III | Series H Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.75%
Liquidation preference		$ 275,000,000	$ 275,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust IV
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust IV | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.375%
Liquidation preference		$ 325,000,000	$ 325,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust IV | Series J Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.375%
Liquidation preference		$ 325,000,000	$ 325,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust V
Unconsolidated Trust
Common stock		$ 10,000	10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust V | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.45%
Liquidation preference		$ 300,000,000	$ 300,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25	$ 25
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust V | Series K Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.45%
Liquidation preference		$ 300,000,000	$ 300,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust VI
Unconsolidated Trust
Common stock		$ 10,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust VI | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)		5.00%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 25
Stock redeemed	$ 475,000,000
SCE | Variable Interest Entity, Not Primary Beneficiary | SCE Trust VI | Series L Preferred Stock
Unconsolidated Trust
Security dividend rate, (as a percent)		5.00%
Liquidation preference		$ 475,000,000
Liquidation value (in dollars per share) | $ / shares		$ 2,500

Variable Interest Entities (Sum

Variable Interest Entities (Summary of Trusts' Income Statement) (Details) - SCE - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SCE Trust I
Variable Interest Entity [Line Items]
Dividend income	$ 14	$ 27	$ 27
Dividend distributions	14	27	27
SCE Trust II
Variable Interest Entity [Line Items]
Dividend income	20	20	20
Dividend distributions	20	20	20
SCE Trust III
Variable Interest Entity [Line Items]
Dividend income	16	16	16
Dividend distributions	16	16	16
SCE Trust IV
Variable Interest Entity [Line Items]
Dividend income	17	17	6
Dividend distributions	17	17	$ 6
SCE Trust V
Variable Interest Entity [Line Items]
Dividend income	16	13
Dividend distributions	16	$ 13
Trust VI
Variable Interest Entity [Line Items]
Dividend income	12
Dividend distributions	$ 12

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value by Level) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets at fair value
Nuclear decommissioning trusts	$ 4,440	$ 4,242
SCE
Assets at fair value
Nuclear decommissioning trusts	$ 4,440	$ 4,242
Liabilities at fair value
Percentage of equity investments located in the United States (as a percent)	69.00%	70.00%
Collateralized mortgage obligations and other asset backed securities	$ 102	$ 79
Payables, net, related to investments	(59)	(127)
SCE | Fair Value, Measurements, Recurring
Assets at fair value
Netting and Collateral	1
Total derivative contracts	110	74
Money market funds and other		33
Nuclear decommissioning trusts	4,499	4,369
Total assets	5,104	4,476
Liabilities at fair value
Derivative contracts	1	1,157
Netting and Collateral	2	0
Total liabilities	1	1,157
Net assets	5,103	3,319
SCE | Fair Value, Measurements, Recurring | Money market funds and other
Assets at fair value
Money market funds and other	495
SCE | Fair Value, Measurements, Recurring | Stocks
Assets at fair value
Nuclear decommissioning trusts	1,596	1,547
SCE | Fair Value, Measurements, Recurring | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	2,730	2,616
SCE | Fair Value, Measurements, Recurring | Short-term investments, primarily cash equivalents
Assets at fair value
Nuclear decommissioning trusts	173	206
SCE | Fair Value, Measurements, Recurring | Level 1
Assets at fair value
Gross amounts recognized	0
Total derivative contracts		0
Money market funds and other		33
Nuclear decommissioning trusts	2,762	2,448
Total assets	3,257	2,481
Liabilities at fair value
Derivative contracts	0	0
Total liabilities	0	0
Net assets	3,257	2,481
SCE | Fair Value, Measurements, Recurring | Level 1 | Money market funds and other
Assets at fair value
Money market funds and other	495
SCE | Fair Value, Measurements, Recurring | Level 1 | Stocks
Assets at fair value
Nuclear decommissioning trusts	1,596	1,547
SCE | Fair Value, Measurements, Recurring | Level 1 | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	1,065	865
SCE | Fair Value, Measurements, Recurring | Level 1 | Short-term investments, primarily cash equivalents
Assets at fair value
Nuclear decommissioning trusts	101	36
SCE | Fair Value, Measurements, Recurring | Level 2
Assets at fair value
Gross amounts recognized	9
Total derivative contracts		6
Money market funds and other		0
Nuclear decommissioning trusts	1,737	1,921
Total assets	1,746	1,927
Liabilities at fair value
Derivative contracts	2	0
Total liabilities	2	0
Net assets	1,744	1,927
SCE | Fair Value, Measurements, Recurring | Level 2 | Money market funds and other
Assets at fair value
Money market funds and other	0
SCE | Fair Value, Measurements, Recurring | Level 2 | Stocks
Assets at fair value
Nuclear decommissioning trusts	0	0
SCE | Fair Value, Measurements, Recurring | Level 2 | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	1,665	1,751
SCE | Fair Value, Measurements, Recurring | Level 2 | Short-term investments, primarily cash equivalents
Assets at fair value
Nuclear decommissioning trusts	72	170
SCE | Fair Value, Measurements, Recurring | Level 3
Assets at fair value
Gross amounts recognized	102
Total derivative contracts		68
Money market funds and other		0
Nuclear decommissioning trusts	0	0
Total assets	102	68
Liabilities at fair value
Derivative contracts	1	1,157
Total liabilities	1	1,157
Net assets	101	(1,089)
SCE | Fair Value, Measurements, Recurring | Level 3 | Money market funds and other
Assets at fair value
Money market funds and other	0
SCE | Fair Value, Measurements, Recurring | Level 3 | Stocks
Assets at fair value
Nuclear decommissioning trusts	0	0
SCE | Fair Value, Measurements, Recurring | Level 3 | Fixed Income
Assets at fair value
Nuclear decommissioning trusts	0	0
SCE | Fair Value, Measurements, Recurring | Level 3 | Short-term investments, primarily cash equivalents
Assets at fair value
Nuclear decommissioning trusts	$ 0	$ 0

Fair Value Measurements (Textua

Fair Value Measurements (Textual) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 1,024	$ 41
Edison International Parent and Other | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 541	$ 23

Fair Value Measurements (Level

Fair Value Measurements (Level 3 Rollforward) (Details) - SCE - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Total realized/unrealized gains:
Reclassified derivative liabilities	$ 914
Level 3
Fair Value Disclosures Level 3 [Roll Forward]
Fair value of net liabilities at beginning of period		$ (1,089)	$ (1,148)
Total realized/unrealized gains:
Included in regulatory assets and liabilities		133	59
Contract amendment		143	0
Normal purchase and normal sale designation		914	0
Fair value of net assets (liabilities) at end of period		101	(1,089)
Change during the period in unrealized gains and losses related to assets and liabilities held at the end of the period		$ 100	$ (70)
Reclassified derivative liabilities	$ 914

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details) - SCE $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)$ / MWhMW	Dec. 31, 2016USD ($)$ / MWhMW
Quantitative Information About Level 3 Measurements [Line Items]
Reclassified derivative liabilities | $	$ 914
Level 3
Quantitative Information About Level 3 Measurements [Line Items]
Reclassified derivative liabilities | $	$ 914
Level 3 | Congestion revenue rights | Market simulation model and auction prices
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets | $		$ 102	$ 67
Fair Value, Liabilities | $		$ 0	$ 0
Level 3 | Congestion revenue rights | Market simulation model and auction prices | Load forecast | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts) | MW		5,002	3,708
Level 3 | Congestion revenue rights | Market simulation model and auction prices | Load forecast | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair value inputs, power units (in megawatts) | MW		22,970	22,840
Level 3 | Congestion revenue rights | Market simulation model and auction prices | Power prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)		(15)	3.65
Level 3 | Congestion revenue rights | Market simulation model and auction prices | Power prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)		120	99.58
Level 3 | Congestion revenue rights | Market simulation model and auction prices | Gas prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)		2.46	2.51
Level 3 | Congestion revenue rights | Market simulation model and auction prices | Gas prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)		4.37	4.87
Level 3 | Congestion revenue rights | Market simulation model and auction prices | CAISO CRR auction clearing prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)		(9.41)
Level 3 | Congestion revenue rights | Market simulation model and auction prices | CAISO CRR auction clearing prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)		8.66
Level 3 | Tolling3 | Option model
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value, Assets | $			$ 0
Fair Value, Liabilities | $			$ 1,154
Level 3 | Tolling3 | Option model | Power prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)			23.40
Expected volatility rate (as a percent)			29.00%
Level 3 | Tolling3 | Option model | Power prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Fair Value Inputs, price level ($ per MWh)			51.24
Expected volatility rate (as a percent)			71.00%
Level 3 | Tolling3 | Option model | Gas prices | Minimum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)			15.00%
Level 3 | Tolling3 | Option model | Gas prices | Maximum
Quantitative Information About Level 3 Measurements [Line Items]
Expected volatility rate (as a percent)			48.00%

Fair Value Measurements (Fair68

Fair Value Measurements (Fair Value of Long-Term Debt Recorded at Carrying Value) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value of Long-Term Debt Recorded at Carrying Value
Carrying Value	$ 12,123	$ 11,156
Fair Value	13,760	12,368
SCE
Fair Value of Long-Term Debt Recorded at Carrying Value
Carrying Value	10,907	10,333
Fair Value	$ 12,547	$ 11,539

Debt and Credit Agreements (Lon

Debt and Credit Agreements (Long-term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Current portion of long-term debt	$ (481)	$ (981)
Long-term debt	11,642	10,175
Edison International Parent and Other
Debt Instrument [Line Items]
Other long-term debt	29	32
Current portion of long-term debt	(2)	(402)
Unamortized debt discount and issuance costs, net	(13)	(9)
Long-term debt	1,214	421
Edison International Parent and Other | Debentures and notes
Debt Instrument [Line Items]
Long-term debt	$ 1,200	800
Edison International Parent and Other | Debentures and notes | Minimum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	2.125%
Edison International Parent and Other | Debentures and notes | Maximum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	2.95%
SCE
Debt Instrument [Line Items]
Current portion of long-term debt	$ (479)	(579)
Unamortized debt discount and issuance costs, net	(88)	(105)
Long-term debt	10,428	9,754
SCE | Debentures and notes
Debt Instrument [Line Items]
Long-term debt	$ 307	307
SCE | Debentures and notes | Minimum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	5.06%
SCE | Debentures and notes | Maximum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	6.65%
SCE | First and refunding mortgage bonds
Debt Instrument [Line Items]
Long-term debt	$ 9,779	9,357
SCE | First and refunding mortgage bonds | Minimum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	1.845%
SCE | First and refunding mortgage bonds | Maximum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	6.05%
SCE | Pollution-control bonds
Debt Instrument [Line Items]
Long-term debt	$ 909	$ 774
SCE | Pollution-control bonds | Minimum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	1.375%
SCE | Pollution-control bonds | Maximum
Debt Instrument [Line Items]
Interest rate on debt (as a percent)	5.00%

Debt and Credit Agreements (L70

Debt and Credit Agreements (Long-term debt maturities) (Details) $ in Millions	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
2,018	$ 481
2,019	81
2,020	481
2,021	580
2,022	777
SCE
Debt Instrument [Line Items]
2,018	479
2,019	79
2,020	79
2,021	579
2,022	$ 364

Debt and Credit Agreements (Tex

Debt and Credit Agreements (Textual) (Details) - USD ($)	1 Months Ended		12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Carrying value		$ 12,123,000,000	$ 12,123,000,000	$ 11,156,000,000
Short-term debt		2,393,000,000	2,393,000,000	1,307,000,000
Line of credit
Debt Instrument [Line Items]
Borrowings from credit facility		500,000,000
Line of credit | Subsequent event
Debt Instrument [Line Items]
Repayment on borrowings	$ 500,000,000
Multi-year credit facilities
Debt Instrument [Line Items]
Commitment		1,250,000,000	1,250,000,000
Outstanding borrowings		1,139,000,000	1,139,000,000	$ 538,000,000
Weighted average interest rate (as a percent)				0.97%
Outstanding letters of credit		0	0
Multi-year credit facilities | Commercial paper
Debt Instrument [Line Items]
Outstanding borrowings		$ 639,000,000	$ 639,000,000
Weighted average interest rate (as a percent)		1.70%	1.70%
Indirect subsidiary of Edison Energy Group | Non-recourse debt financing to support equity investments in solar rooftop projects
Debt Instrument [Line Items]
Carrying value		$ 31,000,000	$ 31,000,000	$ 22,000,000
Short-term debt		$ 16,000,000	$ 16,000,000
Weighted average interest rate on long term debt		4.50%	4.50%	4.86%
Remaining borrowings available		$ 67,000,000	$ 67,000,000
Indirect subsidiary of Edison Energy Group | Non-recourse debt, 2 tax equity financing to support equity investments in solar rooftop projects
Debt Instrument [Line Items]
Remaining borrowings available		21,000,000	$ 21,000,000
Percentage of taxable profits and losses and tax credits			99.00%
Period following the completion of the portfolio of projects (term)			6 years
Priority return on investment (percent)			2.00%
Percentage of taxable profits and losses and cash flow			5.00%
Call option, period			9 months
Period after project completion			5 years
Indirect subsidiary of Edison Energy Group | Non-recourse debt third equity financing to support equity investments in solar rooftop projects
Debt Instrument [Line Items]
Remaining borrowings available		38,000,000	$ 38,000,000
Percentage of taxable profits and losses and tax credits			99.00%
Period following the completion of the portfolio of projects (term)			20 years
Taxable income and losses after the initial period			67.00%
Cash flows until certain conditions are met			28.40%
Indirect subsidiaries | Non-recourse debt financing to support equity investments in solar rooftop projects
Debt Instrument [Line Items]
Carrying value		$ 10,000,000	$ 10,000,000	$ 10,000,000
Weighted average interest rate on long term debt		9.00%	9.00%	9.00%
SCE
Debt Instrument [Line Items]
Carrying value		$ 10,907,000,000	$ 10,907,000,000	$ 10,333,000,000
Short-term debt		$ 1,238,000,000	$ 1,238,000,000	769,000,000
Weighted average interest rate (as a percent)		2.56%	2.56%
SCE | Line of credit
Debt Instrument [Line Items]
Borrowings from credit facility		$ 500,000,000
SCE | Line of credit | Subsequent event
Debt Instrument [Line Items]
Repayment on borrowings	500,000,000
SCE | Multi-year credit facilities
Debt Instrument [Line Items]
Commitment		2,750,000,000	$ 2,750,000,000
Outstanding borrowings		$ 1,238,000,000	$ 1,238,000,000
Weighted average interest rate (as a percent)		2.46%	2.46%
Outstanding letters of credit		$ 99,000,000	$ 99,000,000
SCE | Multi-year credit facilities | Commercial paper
Debt Instrument [Line Items]
Outstanding borrowings				$ 769,000,000
Weighted average interest rate (as a percent)		1.75%	1.75%	0.90%
SCE | Multi-year credit facilities | Letters of credit
Debt Instrument [Line Items]
Outstanding letters of credit		$ 99,000,000	$ 99,000,000
SCE | Commercial paper supported by SCE's credit facility | Commercial paper
Debt Instrument [Line Items]
Outstanding borrowings		$ 738,000,000	$ 738,000,000
Edison International Parent and Other | Term Loan Agreement | Subsequent event
Debt Instrument [Line Items]
Debt, face amount	$ 500,000,000
Basis points	60.00%

Debt and Credit Agreements (Sum

Debt and Credit Agreements (Summary for status of credit facilities) (Details) - Multi-year credit facilities - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Commitment	$ 1,250,000,000
Outstanding borrowings	(1,139,000,000)	$ (538,000,000)
Outstanding letters of credit	0
Amount available	111,000,000
SCE
Line of Credit Facility [Line Items]
Commitment	2,750,000,000
Outstanding borrowings	(1,238,000,000)
Outstanding letters of credit	(99,000,000)
Amount available	$ 1,413,000,000

Derivative Instruments (Textual

Derivative Instruments (Textual) (Details) - SCE - Electric Utility - Economic hedges - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivatives
Aggregate fair value of all derivative liabilities with credit-risk-related contingent features	$ 1	$ 12
Posted collateral	1	$ 12
Potential amount of collateral to be posted if contingencies triggered	20
Payables
Derivatives
Potential amount of collateral to be posted if contingencies triggered	$ 19

Derivative Instruments (Balance

Derivative Instruments (Balance Sheet Disclosures) (Details) - SCE - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Net Liability
Reclassified derivative liabilities	$ 914
Commodity derivative contracts | Electric Utility
Derivative Assets
Gross amounts recognized		$ 111	$ 75
Gross amounts offset in the consolidated balance sheets		(1)	(1)
Cash collateral posted		0	0
Net amounts presented in the consolidated balance sheets		110	74
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		3	1,158
Gross amounts offset in the consolidated balance sheets		(1)	(1)
Cash collateral posted		(1)	0
Net amounts presented in the consolidated balance sheets		1	1,157
Net Liability
Gross amounts recognized		108	(1,083)
Gross amounts offset in the consolidated balance sheets		0	0
Cash collateral posted		1	0
Net amounts presented in the consolidated balance sheets		109	(1,083)
Commodity derivative contracts | Derivative Assets, Short-Term | Electric Utility
Derivative Assets
Gross amounts recognized		106	74
Gross amounts offset in the consolidated balance sheets		(1)	(1)
Cash collateral posted		0	0
Net amounts presented in the consolidated balance sheets		105	73
Commodity derivative contracts | Derivative Assets, Long-Term | Electric Utility
Derivative Assets
Gross amounts recognized		5	1
Gross amounts offset in the consolidated balance sheets		0	0
Cash collateral posted		0	0
Net amounts presented in the consolidated balance sheets		5	1
Commodity derivative contracts | Derivative Liability, Short-Term | Electric Utility
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		3	217
Gross amounts offset in the consolidated balance sheets		(1)	(1)
Cash collateral posted		(1)	0
Net amounts presented in the consolidated balance sheets		1	216
Commodity derivative contracts | Derivative Liability, Long-Term | Electric Utility
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		0	941
Gross amounts offset in the consolidated balance sheets		0	0
Cash collateral posted		0	0
Net amounts presented in the consolidated balance sheets		$ 0	941
Commodity derivative contracts | Other Current Liabilities
Net Liability
Cash collateral			$ 2

Derivative Instruments (Summari

Derivative Instruments (Summarization of Economic Hedging Activities) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Realized losses	$ (14)	$ (59)	$ (148)
Unrealized gains (losses)	$ 106	$ 84	$ (182)

Derivative Instruments (Notiona

Derivative Instruments (Notional Values) (Details) - SCE - Electric Utility - Gross amounts recognized MWh in Thousands	Dec. 31, 2017BcfeMWh	Dec. 31, 2016BcfeMWh
Electricity options, swaps and forwards (GWh)
Derivatives
Notional volumes of derivative instruments	475	1,816
Natural gas options, swaps and forwards (Bcf)
Derivatives
Notional volumes of derivative instruments | Bcfe	143	36
Congestion revenue rights (GWh)
Derivatives
Notional volumes of derivative instruments	78,765	93,319
Tolling arrangements (GWh)
Derivatives
Notional volumes of derivative instruments	0	61,093

Income Taxes (Source of Income

Income Taxes (Source of Income (Loss) Before Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income from continuing operations before income taxes	$ 949	$ 1,590	$ 1,568
Income from discontinued operations before income taxes	0	1	15
Income before income tax	$ 949	$ 1,591	$ 1,583

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense (Benefit) by Location) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ (221)	$ (46)	$ 18
State	4	33	19
Total current	(217)	(13)	37
Deferred:
Federal	570	176	340
State	(72)	14	109
Total deferred	498	190	449
Total continuing operations	281	177	486
Discontinued operations	0	(11)	(21)
Total	281	166	465
SCE
Current:
Federal	(253)	75	72
State	(81)	93	127
Total current	(334)	168	199
Deferred:
Federal	265	112	298
State	39	(24)	10
Total deferred	304	88	308
Total continuing operations	(30)	256	507
Discontinued operations	0	0	0
Total	$ (30)	$ 256	$ 507

Income Taxes (Components of Net

Income Taxes (Components of Net Accumulated Deferred Income Tax Liability) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Property and software related	$ 358	$ 549
Nuclear decommissioning trust assets in excess of nuclear ARO liability	404	348
Loss and credit carryforwards	1,346	1,418
Regulatory asset	812	15
Pension and postretirement benefits other than pensions	214	300
Other	277	419
Sub-total	3,411	3,049
Less valuation allowance	28	24
Total	3,383	3,025
Deferred tax liabilities:
Property-related	6,970	10,330
Capitalized software costs	160	237
Regulatory liability	158	134
Nuclear decommissioning trust assets	404	348
Postretirement benefits other than pensions	36	13
Other	140	202
Total	7,868	11,264
Accumulated deferred income tax liability, net	4,485	8,239
Recorded valuation allowance	28
Unrecognized tax benefits	432	471	$ 529	$ 576
Regulatory asset	809
Loss And Credit Carryforwards
Deferred tax liabilities:
Unrecognized tax benefits	77
SCE
Deferred tax assets:
Property and software related	357	548
Nuclear decommissioning trust assets in excess of nuclear ARO liability	404	348
Loss and credit carryforwards	150	0
Regulatory asset	812	15
Pension and postretirement benefits other than pensions	86	93
Other	236	408
Sub-total	2,045	1,412
Less valuation allowance	0	0
Total	2,045	1,412
Deferred tax liabilities:
Property-related	6,962	10,330
Capitalized software costs	160	237
Regulatory liability	158	134
Nuclear decommissioning trust assets	404	348
Postretirement benefits other than pensions	36	13
Other	133	148
Total	7,853	11,210
Accumulated deferred income tax liability, net	5,808	9,798
Unrecognized tax benefits	331	$ 371	$ 353	$ 441
SCE | Loss And Credit Carryforwards
Deferred tax liabilities:
Unrecognized tax benefits	$ 75

Income Taxes (Textual) (Details

Income Taxes (Textual) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2016	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2015	Mar. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Line Items]
Accumulated deferred income net income tax liabilities			$ 4,500
Re-measurement of federal net operating loss carryforwards			466
Unrecognized tax benefits that would impact the effective tax rate			308			$ 347
Tax Years 2007 To 2012
Income Tax Disclosure [Line Items]
Expected refund					$ (7)
Disallowance of Repair Allowance Deduction
Income Tax Disclosure [Line Items]
Base rate offset				$ 324
Rate base offset amortization period (years)				27 years
Capistrano Wind | Affiliated Entity | Tax Allocation Agreement
Income Tax Disclosure [Line Items]
Due to affiliate under tax allocation agreements			199			242
SCE
Income Tax Disclosure [Line Items]
Accumulated deferred income net income tax liabilities			5,000
Changes to earnings charge			33
Granted BRRBA reduction	$ 234
Refund		$ 133
After tax refund		$ 79
Unrecognized tax benefits that would impact the effective tax rate			$ 167			$ 243
SCE | Disallowance of Repair Allowance Deduction
Income Tax Disclosure [Line Items]
Federal tax liability				$ 382

Income Taxes (Net Operating Los

Income Taxes (Net Operating Loss and Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2017USD ($)
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2018 to 2036	$ 901
Loss Carryforwards, No expiration date	0
Loss Carryforwards	901
Credit Carryforward, Expiring 2018 to 2036	451
Credit Carryforward, No expiration date	71
Credit Carryforwards	522
SCE
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2018 to 2036	162
Loss Carryforwards, No expiration date	0
Loss Carryforwards	162
Credit Carryforward, Expiring 2018 to 2036	25
Credit Carryforward, No expiration date	38
Credit Carryforwards	$ 63

Income Taxes (Tax Rate Reconcil

Income Taxes (Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Income from continuing operations before income taxes	$ 949	$ 1,590	$ 1,568
Provision for income tax at federal statutory rate of 35%	$ 332	$ 556	$ 549
Federal statutory rate	35.00%	35.00%	35.00%
Increase in income tax from:
Regulatory asset write-off	$ 0	$ 0	$ 382
State tax, net of federal benefit	2	29	5
Property-related	(439)	(362)	(341)
Change related to uncertain tax positions	(18)	(4)	(67)
Revised San Onofre Settlement Agreement	25	0	0
Share-based compensation	(55)	(28)	0
Effective Income Tax Rate Reconciliation,Tax Cuts and Jobs Act of 2017, Amount	466	0	0
Other	(32)	(14)	(42)
Total continuing operations	$ 281	$ 177	$ 486
Effective tax rate	29.60%	11.10%	31.00%
State
Increase in income tax from:
Share-based compensation	$ (11)	$ (4)
SCE
Income Tax Disclosure [Line Items]
Income from continuing operations before income taxes	1,106	1,755	$ 1,618
Provision for income tax at federal statutory rate of 35%	387	614	566
Increase in income tax from:
Regulatory asset write-off	0	0	382
State tax, net of federal benefit	8	43	34
Property-related	(439)	(362)	(341)
Change related to uncertain tax positions	(13)	(8)	(94)
Revised San Onofre Settlement Agreement	25	0	0
Share-based compensation	(11)	(13)	0
Effective Income Tax Rate Reconciliation,Tax Cuts and Jobs Act of 2017, Amount	33	0	0
Other	(20)	(18)	(40)
Total continuing operations	$ (30)	$ 256	$ 507
Effective tax rate	(2.70%)	14.60%	31.30%
SCE | State
Increase in income tax from:
Share-based compensation	$ (2)	$ (1)
SCE | Tax accounting method changes | IRS Examination
Increase in income tax from:
Federal tax liability	80
Tax benefits related to tax accounting method changes, pre-tax	$ 135

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits
Balance at January 1,	$ 471	$ 529	$ 576
Tax positions taken during the current year, Increases	51	36	54
Tax positions taken during a prior year, Increases	0	2	66
Tax positions taken during a prior year, Decreases	(7)	(96)	(165)
Tax positions taken during a prior year, Decreases for settlements during the period	(83)	0	(2)
Balance at December 31,	432	471	529
SCE
Reconciliation of Unrecognized Tax Benefits
Balance at January 1,	371	353	441
Tax positions taken during the current year, Increases	51	36	48
Tax positions taken during a prior year, Increases	0	0	23
Tax positions taken during a prior year, Decreases	(13)	(18)	(159)
Tax positions taken during a prior year, Decreases for settlements during the period	(78)	0	0
Balance at December 31,	$ 331	$ 371	$ 353

Income Taxes (Interest and Pena

Income Taxes (Interest and Penalties Related to Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Accrued interest and penalties	$ 115	$ 128
Net after-tax interest and penalties tax expense (benefit)	6	6	$ (9)
SCE
Income Tax Disclosure [Line Items]
Accrued interest and penalties	41	41
Net after-tax interest and penalties tax expense (benefit)	$ 4	$ 2	$ (14)

Compensation and Benefit Plan85

Compensation and Benefit Plans (Employee Savings Plan) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plans [Line Items]
Employer contributions	$ 70	$ 69	$ 73
SCE
Defined Contribution Plans [Line Items]
Employer contributions	$ 69	$ 68	$ 72

Compensation and Benefit Plan86

Compensation and Benefit Plans (Textual) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assumed average equity risk premium (percent)	5.00%
Forecasted return on private equity and opportunistic investments (percent)	2.00%
Performance incentive plan award (shares)	66
Share-based compensation, shares available for grant	30
Stock options
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Stock options, expiration period, years	10 years
Stock options, vesting period, years	4 years
Volatility period	68 months	71 months	71 months
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contributions	$ 66
Permissible range of asset class weights (percent)	3.00%
Publicly traded equity investments located in the US (percent)	67.00%	69.00%
Pension Plans | US Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	29.00%
Pension Plans | Non-US Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	17.00%
Pension Plans | Fixed Income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	35.00%
Pension Plans | Opportunistic Alternative Investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	15.00%
Pension Plans | Other Investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	4.00%
Postretirement Benefits Other Than Pensions
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contributions	$ 12
Eligibility age	55 years
Service period for eligibility (at least) (years)	10 years
Publicly traded equity investments located in the US (percent)	61.00%	63.00%
Postretirement Benefits Other Than Pensions | US Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	58.00%
Postretirement Benefits Other Than Pensions | Fixed Income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	29.00%
Postretirement Benefits Other Than Pensions | Opportunistic Alternative Investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	13.00%
Voluntary Employee Beneficiary Association (VEBA) | Fixed Income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	85.00%
Voluntary Employee Beneficiary Association (VEBA) | Opportunistic Alternative Investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	5.00%
Voluntary Employee Beneficiary Association (VEBA) | Global Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target plan asset allocations (percent)	10.00%
SCE | Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected contributions	$ 50

Compensation and Benefit Plan87

Compensation and Benefit Plans (Plan Assets and Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in projected benefit obligation
Service cost	$ 169
Amounts recognized in the consolidated balance sheets consist of:
Long-term liabilities	(943)	$ (1,354)
SCE
Change in projected benefit obligation
Service cost	164
Amounts recognized in the consolidated balance sheets consist of:
Long-term liabilities	(483)	(896)
Pension Plans
Change in projected benefit obligation
Projected benefit obligation at beginning of year	4,284	4,374
Service cost	137	139
Interest cost	164	171
Actuarial gain	(46)	(125)
Benefits paid	(360)	(275)
Projected benefit obligation at end of year	4,179	4,284	$ 4,374
Change in plan assets
Fair value of plan assets at beginning of year	3,388	3,298
Actual return on plan assets	483	262
Employer contributions	105	103
Benefits paid	(360)	(275)
Fair value of plan assets at end of year	3,616	3,388	3,298
Funded status at end of year	(563)	(896)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	7	2
Current liabilities	(17)	(50)
Long-term liabilities	(553)	(848)
Total liabilities	(563)	(896)
Amounts recognized in accumulated other comprehensive loss consist of:
Prior service cost	(1)	(1)
Net loss	(77)	(93)
Total amounts recognized in accumulated other comprehensive loss	(76)	(92)
Amounts recognized as a regulatory (liability) asset	271	574
Total not yet recognized as (income) expense	347	666
Accumulated benefit obligation at end of year	4,022	4,138
Pension plans with an accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	4,179	4,284
Accumulated benefit obligation	4,022	4,138
Fair value of plan assets	$ 3,616	$ 3,388
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.46%	3.94%
Rate of compensation increase	4.10%	4.00%
Pension Plans | Edison International
Assumed health care cost trend rates:
Long-term payable	$ 114	$ 124
Pension Plans | SCE
Change in projected benefit obligation
Projected benefit obligation at beginning of year	3,791	3,878
Service cost	129	132
Interest cost	144	150
Actuarial gain	(74)	(140)
Benefits paid	(288)	(229)
Projected benefit obligation at end of year	3,702	3,791	3,878
Change in plan assets
Fair value of plan assets at beginning of year	3,172	3,080
Actual return on plan assets	442	239
Employer contributions	64	82
Benefits paid	(288)	(229)
Fair value of plan assets at end of year	3,390	3,172	3,080
Funded status at end of year	(312)	(619)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	0	0
Current liabilities	(4)	(4)
Long-term liabilities	(308)	(615)
Total liabilities	(312)	(619)
Amounts recognized in accumulated other comprehensive loss consist of:
Prior service cost	0	0
Net loss	(21)	(24)
Total amounts recognized in accumulated other comprehensive loss	(21)	(24)
Amounts recognized as a regulatory (liability) asset	271	574
Total not yet recognized as (income) expense	292	598
Accumulated benefit obligation at end of year	3,585	3,683
Pension plans with an accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	3,702	3,791
Accumulated benefit obligation	3,585	3,683
Fair value of plan assets	$ 3,390	$ 3,172
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.46%	3.94%
Rate of compensation increase	4.10%	4.00%
Assumed health care cost trend rates:
Net loss reclassified from other comprehensive loss	$ 19	$ 20
Postretirement Benefits Other Than Pensions
Change in projected benefit obligation
Projected benefit obligation at beginning of year	2,276	2,350
Service cost	31	35	46
Interest cost	86	97	102
Special termination benefits	1	2
Plan Amendments	0	(6)
Actuarial gain	24	(110)
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Projected benefit obligation at end of year	2,337	2,276	2,350
Change in plan assets
Fair value of plan assets at beginning of year	2,102	2,036
Actual return on plan assets	297	137
Employer contributions	12	21
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Fair value of plan assets at end of year	2,330	2,102	2,036
Funded status at end of year	(7)	(174)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	6	0
Current liabilities	(13)	(14)
Long-term liabilities	0	(160)
Total liabilities	(7)	(174)
Amounts recognized in accumulated other comprehensive loss consist of:
Total amounts recognized in accumulated other comprehensive loss	(4)	(4)
Amounts recognized as a regulatory (liability) asset	(26)	136
Total not yet recognized as (income) expense	$ (22)	$ 140
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.70%	4.29%
Assumed health care cost trend rates:
Rate assumed for following year	6.75%	7.00%
Ultimate rate	5.00%	5.00%
Postretirement Benefits Other Than Pensions | SCE
Change in projected benefit obligation
Projected benefit obligation at beginning of year	$ 2,266	$ 2,341
Service cost	31	34	46
Interest cost	85	97	102
Special termination benefits	1	2
Plan Amendments	0	(6)
Actuarial gain	23	(110)
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Projected benefit obligation at end of year	2,325	2,266	2,341
Change in plan assets
Fair value of plan assets at beginning of year	2,102	2,036
Actual return on plan assets	297	137
Employer contributions	12	21
Plan participants' contributions	24	19
Benefits paid	(105)	(111)
Fair value of plan assets at end of year	2,330	2,102	$ 2,036
Funded status at end of year	5	(164)
Amounts recognized in the consolidated balance sheets consist of:
Long-term assets	17	0
Current liabilities	(12)	(13)
Long-term liabilities	0	(151)
Total liabilities	5	(164)
Amounts recognized in accumulated other comprehensive loss consist of:
Total amounts recognized in accumulated other comprehensive loss	0	0
Amounts recognized as a regulatory (liability) asset	(26)	136
Total not yet recognized as (income) expense	$ (26)	$ 136
Weighted-average assumptions used to determine obligations at end of year:
Discount rate	3.70%	4.29%
Assumed health care cost trend rates:
Rate assumed for following year	6.75%	7.00%
Ultimate rate	5.00%	5.00%

Compensation and Benefit Plan88

Compensation and Benefit Plans (Expense Components) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Other Postretirement Benefits
Service cost	$ 169
Pension Plans
Pension and Other Postretirement Benefits
Service cost	137	$ 139
Interest cost	164	171
Settlement loss	(6.4)
Settlement loss, net of tax	(3.8)
Other	(10)	(10)	$ (14)
Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Service cost	31	35	46
Interest cost	86	97	102
Expected return on plan assets	(110)	(112)	(116)
Settlement costs	1	2	1
Amortization of prior service cost	(3)	(2)	(12)
Amortization of net loss	0	0	3
Expense under accounting standards	5	20	24
SCE
Pension and Other Postretirement Benefits
Service cost	164
SCE | Pension Plans
Pension and Other Postretirement Benefits
Service cost	129	132
Interest cost	144	150
Other	(6)	(6)	(8)
SCE | Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Service cost	31	34	46
Interest cost	85	97	102
Expected return on plan assets	(110)	(112)	(116)
Settlement costs	1	2	1
Amortization of prior service cost	(2)	(2)	(12)
Amortization of net loss	0	0	2
Expense under accounting standards	5	19	23
Continuing Operations | Pension Plans
Pension and Other Postretirement Benefits
Service cost	138	139	142
Interest cost	164	172	170
Expected return on plan assets	(212)	(220)	(233)
Settlement costs	6	0	0
Amortization of prior service cost	3	4	5
Amortization of net loss	21	27	40
Expense under accounting standards	120	122	124
Regulatory adjustment (deferred)	(28)	(21)	(6)
Total expense recognized	92	101	118
Continuing Operations | SCE | Pension Plans
Pension and Other Postretirement Benefits
Service cost	133	136	139
Interest cost	149	156	155
Expected return on plan assets	(199)	(205)	(217)
Settlement costs	0	0	0
Amortization of prior service cost	3	4	5
Amortization of net loss	17	23	35
Expense under accounting standards	103	114	117
Regulatory adjustment (deferred)	(28)	(21)	(6)
Total expense recognized	$ 75	$ 93	$ 111

Compensation and Benefit Plan89

Compensation and Benefit Plans (Changes in Plan Assets and Benefits Obligations Recognized in OCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Unrecognized prior service cost (credit) to be amortized	$ (1)
Pension Plans
Pension and Other Postretirement Benefits
Net loss (gain)	0	$ 6	$ 7
Settlement charges	6	0	0
Amortization of net loss	(10)	(10)	(15)
Total recognized in other comprehensive loss	(16)	(4)	(8)
Total recognized in expense and other comprehensive loss	76	97	110
Unrecognized net loss to be amortized	8
Unrecognized prior service cost (credit) to be amortized	3
Amount of net loss expected to be reclassified from other comprehensive loss	8
SCE | Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Unrecognized prior service cost (credit) to be amortized	(1)
SCE | Pension Plans
Pension and Other Postretirement Benefits
Net loss (gain)	3	4	(9)
Settlement charges	0	0	0
Amortization of net loss	(6)	(6)	(9)
Total recognized in other comprehensive loss	(3)	(2)	(18)
Total recognized in expense and other comprehensive loss	72	$ 91	$ 93
Unrecognized net loss to be amortized	6
Unrecognized prior service cost (credit) to be amortized	3
Amount of net loss expected to be reclassified from other comprehensive loss	$ 6

Compensation and Benefit Plan90

Compensation and Benefit Plans (Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Postretirement Benefits Other Than Pensions
Assumed health care cost trend rates:
Ultimate rate	5.00%	5.00%
Pension Plans
Pension and Other Postretirement Benefits
Discount rate	3.94%	4.18%	3.85%
Rate of compensation increase	4.00%	4.00%	4.00%
Expected long-term return on plan assets	6.50%	7.00%	7.00%
Continuing Operations | Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Discount rate	4.29%	4.55%	4.16%
Expected long-term return on plan assets	5.30%	5.60%	5.50%
Assumed health care cost trend rates:
Current year	7.00%	7.50%	7.75%
Ultimate rate	5.00%	5.00%	5.00%

Compensation and Benefit Plan91

Compensation and Benefit Plans (Expected Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2017USD ($)
Pension Plans
Years ended December 31,
2,018	$ 338
2,019	343
2,020	327
2,021	324
2,022	309
2023 – 2027	1,453
Postretirement Benefits Other Than Pensions
Years ended December 31,
2,018	93
2,019	96
2,020	100
2,021	103
2,022	107
2023 – 2027	582
SCE | Pension Plans
Years ended December 31,
2,018	304
2,019	303
2,020	293
2,021	287
2,022	281
2023 – 2027	1,299
SCE | Postretirement Benefits Other Than Pensions
Years ended December 31,
2,018	93
2,019	96
2,020	100
2,021	103
2,022	106
2023 – 2027	$ 580

Compensation and Benefit Plan92

Compensation and Benefit Plans (Pension Plan Assets - Fair Value Levels) (Details) - Pension Plans - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Other Postretirement Benefits
Fair value of plan assets	$ 3,714	$ 3,548
Fair value NAV	1,363	1,284
Receivables and payables, net	(98)	(160)
Net plan assets available for benefits	3,616	3,388	$ 3,298
Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	1,051	1,103
Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	1,300	1,161
Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
U.S. government and agency securities
Pension and Other Postretirement Benefits
Fair value of plan assets	691	526
Fair value NAV	0	0
U.S. government and agency securities | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	184	217
U.S. government and agency securities | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	507	309
U.S. government and agency securities | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Corporate stocks
Pension and Other Postretirement Benefits
Fair value of plan assets	729	735
Fair value NAV	$ 0	$ 0
Corporate stocks | Russell Indexes
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage	54.00%	62.00%
Corporate stocks | MSCI
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage	46.00%	38.00%
Corporate stocks | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	$ 718	$ 720
Corporate stocks | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	11	15
Corporate stocks | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Corporate bonds
Pension and Other Postretirement Benefits
Fair value of plan assets	676	725
Fair value NAV	0	0
Corporate bonds | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Corporate bonds | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	676	725
Corporate bonds | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Common/collective funds
Pension and Other Postretirement Benefits
Fair value of plan assets	705	692
Fair value NAV	$ 705	$ 692
Common/collective funds | Standard and Poor's 500
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage	41.00%	45.00%
Common/collective funds | Russell 1000 index
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage	15.00%	15.00%
Common/collective funds | MSCI All Country World Index exUS
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage	15.00%	15.00%
Common/collective funds | Non-index U.S. equity fund
Pension and Other Postretirement Benefits
Performance percentage benchmark, percentage	25.00%	23.00%
Common/collective funds | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	$ 0	$ 0
Common/collective funds | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Common/collective funds | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Partnerships/joint ventures
Pension and Other Postretirement Benefits
Fair value of plan assets	396	333
Fair value NAV	$ 396	$ 333
Partnerships/joint ventures | Private equity and venture capital funds including branded consumer products, clean and information technology and healthcare
Pension and Other Postretirement Benefits
Actual plan asset allocations, percentage	55.00%	55.00%
Partnerships/joint ventures | Publicly traded fixed income securities
Pension and Other Postretirement Benefits
Actual plan asset allocations, percentage	23.00%	22.00%
Partnerships/joint ventures | Broad range of financial assets in all global markets
Pension and Other Postretirement Benefits
Actual plan asset allocations, percentage	20.00%	18.00%
Partnerships/joint ventures | Asset backed securities including distressed mortgages
Pension and Other Postretirement Benefits
Actual plan asset allocations, percentage	2.00%	4.00%
Partnerships/joint ventures | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	$ 0	$ 0
Partnerships/joint ventures | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Partnerships/joint ventures | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Other investment entities
Pension and Other Postretirement Benefits
Fair value of plan assets	262	253
Fair value NAV	262	253
Other investment entities | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Other investment entities | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Other investment entities | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Registered investment companies
Pension and Other Postretirement Benefits
Fair value of plan assets	140	130
Fair value NAV	0	6
Registered investment companies | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	140	124
Registered investment companies | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Registered investment companies | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Interest-bearing cash
Pension and Other Postretirement Benefits
Fair value of plan assets	9	42
Fair value NAV	0	0
Interest-bearing cash | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	9	42
Interest-bearing cash | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Interest-bearing cash | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Other
Pension and Other Postretirement Benefits
Fair value of plan assets	106	112
Fair value NAV	0	0
Other | Level 1
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Other | Level 2
Pension and Other Postretirement Benefits
Fair value of plan assets	106	112
Other | Level 3
Pension and Other Postretirement Benefits
Fair value of plan assets	0	0
Collateralized mortgage obligations and other asset backed securities
Pension and Other Postretirement Benefits
Fair value of plan assets	65	76
Mortgage obligations and other asset backed securities, below investment grade	18	27
SCE
Pension and Other Postretirement Benefits
Net plan assets available for benefits	$ 3,390	$ 3,172	$ 3,080

Compensation and Benefit Plan93

Compensation and Benefit Plans (Other Postretirement Plan Assets - Fair Value Levels) (Details) - Postretirement Benefits Other Than Pensions - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net plan assets available for benefits	$ 2,330	$ 2,102	$ 2,036
Corporate stocks | Russell Indexes
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Performance percentage benchmark, percentage	64.00%	47.00%
Corporate stocks | MSCI All Country World Index
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Performance percentage benchmark, percentage	36.00%	53.00%
Common/collective funds | MSCI-EAFE
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual plan asset allocations, percentage	75.00%	39.00%
Common/collective funds | Non-index U.S. equity fund
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual plan asset allocations, percentage	17.00%	18.00%
Partnerships | Private equity and venture capital funds including branded consumer products, clean and information technology and healthcare
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual plan asset allocations, percentage	56.00%	59.00%
Partnerships | Broad range of financial assets in all global markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual plan asset allocations, percentage	33.00%	31.00%
Partnerships | Asset backed securities including distressed mortgages
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual plan asset allocations, percentage	9.00%	9.00%
Other | Municipal securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	$ 60	$ 76
Collateralized mortgage obligations and other asset backed securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Receivables and payables, net	36	47
SCE
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	2,349	2,133
Fair value NAV	651	542
Receivables and payables, net	(19)	(31)
Net plan assets available for benefits	2,330	2,102	$ 2,036
SCE | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	736	552
SCE | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	962	1,039
SCE | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | U.S. government and agency securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	431	281
Fair value NAV	0	0
SCE | U.S. government and agency securities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	398	222
SCE | U.S. government and agency securities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	33	59
SCE | U.S. government and agency securities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Corporate stocks
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	254	230
Fair value NAV	0	0
SCE | Corporate stocks | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	254	230
SCE | Corporate stocks | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Corporate stocks | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Corporate notes and bonds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	845	877
Fair value NAV	0	0
SCE | Corporate notes and bonds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Corporate notes and bonds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	845	877
SCE | Corporate notes and bonds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Common/collective funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	569	462
Fair value NAV	569	462
SCE | Common/collective funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Common/collective funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Common/collective funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Partnerships
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	82	79
Fair value NAV	82	79
SCE | Partnerships | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Partnerships | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Partnerships | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Registered investment companies
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	37	49
Fair value NAV	0	1
SCE | Registered investment companies | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	37	48
SCE | Registered investment companies | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Registered investment companies | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Interest bearing cash
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	42	48
Fair value NAV	0	0
SCE | Interest bearing cash | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	42	48
SCE | Interest bearing cash | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Interest bearing cash | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0	0
SCE | Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	89	107
Fair value NAV	0	0
SCE | Other | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	5	4
SCE | Other | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	84	103
SCE | Other | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	$ 0	$ 0

Compensation and Benefit Plan94

Compensation and Benefit Plans (Effect of Change in One Percent) (Details) - Postretirement Benefits Other Than Pensions $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect on ABO of one-percentage-point increase in assumed health care cost trend rate	$ 247
Effect on ABO of one-percentage-point decrease in assumed health care cost trend rate	(203)
Effect on annual aggregate service and interest costs of one-percentage-point increase in assumed health care cost trend rate	9
Effect on annual aggregate service and interest costs of one-percentage-point decrease in assumed health care cost trend rate	(8)
SCE
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect on ABO of one-percentage-point increase in assumed health care cost trend rate	246
Effect on ABO of one-percentage-point decrease in assumed health care cost trend rate	(202)
Effect on annual aggregate service and interest costs of one-percentage-point increase in assumed health care cost trend rate	9
Effect on annual aggregate service and interest costs of one-percentage-point decrease in assumed health care cost trend rate	$ (8)

Compensation and Benefit Plan95

Compensation and Benefit Plans (Expense and Tax Benefits of Stock Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 23	$ 34	$ 29
Income tax benefits related to stock compensation expense	72	41	12
Excess tax benefits	0	0	15
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	14	14	14
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2	13	7
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	6	6	7
Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1	1	1
SCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	13	16	16
Income tax benefits related to stock compensation expense	15	20	7
Excess tax benefits	0	0	23
SCE | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	8	7	8
SCE | Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2	6	4
SCE | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3	3	4
SCE | Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0	$ 0	$ 0

Compensation and Benefit Plan96

Compensation and Benefit Plans (Black-Scholes Option Pricing Model Assumptions) (Details) - Stock options	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected terms (in years)	5 years 8 months 12 days	5 years 10 months 24 days	5 years 10 months 24 days
Risk-free interest rate, minimum	2.10%	1.20%	1.60%
Risk-free interest rate, maximum	2.30%	2.20%	2.10%
Weighted-average expected dividend yield	2.70%	2.90%	2.60%
Expected volatility, minimum	17.80%	17.20%	16.40%
Expected volatility, maximum	20.90%	17.50%	17.00%
Weighted-average volatility	17.90%	17.40%	16.50%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	2.70%	2.50%	2.60%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	3.80%	3.00%	3.20%

Compensation and Benefit Plan97

Compensation and Benefit Plans (Stock Option Activity) (Details) - Stock options $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Stock options
Beginning balance (number of options) | shares	11,544,501
Grants (number of options) | shares	1,359,599
Expired (number of options) | shares	0
Forfeited (number of options) | shares	(163,449)
Exercised (number of options) | shares	(4,918,086)
Ending balance (number of options) | shares	7,822,565
Vested and expected to vest (number of options) | shares	7,740,798
Exercisable (number of options) | shares	4,241,658
Exercise Price
Beginning balance, weighted average exercise price (dollars per share) | $ / shares	$ 50.26
Granted, weighted average exercise price (dollars per share) | $ / shares	79.23
Expired, weighted average exercise price (dollars per share) | $ / shares	0
Forfeited, weighted average exercise price (dollars per share) | $ / shares	69.76
Exercised, weighted average exercise price (dollars per share) | $ / shares	43.77
Ending balance, weighted average exercise price (dollars per share) | $ / shares	58.98
Vested and expected to vest, weighted average exercise price (dollars per share) | $ / shares	58.81
Exercisable, weighted average exercise price (dollars per share) | $ / shares	$ 50.48
Remaining Contractual Term (Years)
Outstanding at December 31, 2016 (term)	6 years 4 months 13 days
Vested and expected to vest at December 31, 2016 (term)	6 years 4 months 6 days
Exercisable at December 31, 2016 (term)	5 years 1 month 2 days
Aggregate Intrinsic Value (in millions)
Vested and expected to vest at December 31, 2017 | $	$ 62
Exercisable at December 31, 2017 | $	$ 58
SCE
Stock options
Beginning balance (number of options) | shares	4,727,416
Grants (number of options) | shares	699,538
Expired (number of options) | shares	0
Forfeited (number of options) | shares	(77,165)
Exercised (number of options) | shares	(987,161)
Transfers, net (number of options) | shares	83,074
Ending balance (number of options) | shares	4,445,702
Vested and expected to vest (number of options) | shares	4,402,254
Exercisable (number of options) | shares	2,555,160
Exercise Price
Beginning balance, weighted average exercise price (dollars per share) | $ / shares	$ 51.81
Granted, weighted average exercise price (dollars per share) | $ / shares	79.12
Expired, weighted average exercise price (dollars per share) | $ / shares	0
Forfeited, weighted average exercise price (dollars per share) | $ / shares	66.27
Exercised, weighted average exercise price (dollars per share) | $ / shares	48.63
Transfers, net, weighted average exercise price (dollars per share) | $ / shares	46.47
Ending balance, weighted average exercise price (dollars per share) | $ / shares	56.46
Vested and expected to vest, weighted average exercise price (dollars per share) | $ / shares	56.28
Exercisable, weighted average exercise price (dollars per share) | $ / shares	$ 46.94
Remaining Contractual Term (Years)
Outstanding at December 31, 2016 (term)	5 years 11 months 27 days
Vested and expected to vest at December 31, 2016 (term)	5 years 11 months 16 days
Exercisable at December 31, 2016 (term)	4 years 6 months 7 days
Aggregate Intrinsic Value (in millions)
Vested and expected to vest at December 31, 2017 | $	$ 45
Exercisable at December 31, 2017 | $	$ 43

Compensation and Benefit Plan98

Compensation and Benefit Plans (Unrecognized Compensation Costs) (Details) - Stock options $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Pension and Other Postretirement Benefits
Unrecognized compensation cost, net of expected forfeitures	$ 13
Weighted-average period (in years)	2 years 4 months 24 days
SCE
Pension and Other Postretirement Benefits
Unrecognized compensation cost, net of expected forfeitures	$ 7
Weighted-average period (in years)	2 years 3 months 18 days

Compensation and Benefit Plan99

Compensation and Benefit Plans (Supplemental Data on Stock Options) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash from participants to exercise stock options	$ 215	$ 135	$ 128
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value per option granted (dollars per share)	$ 10.65	$ 7.38	$ 7.54
Fair value of options vested	$ 11	$ 11	$ 20
Cash used to purchase shares to settle options	293	220	170
Cash from participants to exercise stock options	167	136	113
Value of options exercised	126	84	57
Tax benefits from options exercised	51	34	23
SCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash from participants to exercise stock options	$ 48	$ 76	$ 68
SCE | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value per option granted (dollars per share)	$ 10.63	$ 7.50	$ 7.53
Fair value of options vested	$ 5	$ 5	$ 11
Cash used to purchase shares to settle options	77	118	69
Cash from participants to exercise stock options	48	77	45
Value of options exercised	29	41	24
Tax benefits from options exercised	$ 12	$ 17	$ 10

Compensation and Benefit Pla100

Compensation and Benefit Plans (Nonvested Performance Share Activity) (Details) - Performance shares	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Shares
Beginning balance (number of shares)	207,497
Granted (number of shares)	81,874
Forfeited (number of shares)	(53,002)
Vested (number of shares)	(57,247)
Ending balance (number of shares)	179,122
Weighted-Average Grant Date Fair Value
Beginning balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 84.30
Ending balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 63.85
SCE
Shares
Beginning balance (number of shares)	96,667
Granted (number of shares)	42,569
Forfeited (number of shares)	(25,061)
Vested (number of shares)	(26,427)
Affiliate transfers, net (number of shares)	974
Ending balance (number of shares)	88,722
Weighted-Average Grant Date Fair Value
Beginning balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 84.25
Ending balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 64.01

Compensation and Benefit Pla101

Compensation and Benefit Plans (Restricted Stock Unit Activity) (Details) - Restricted stock units	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Restricted Stock Units
Beginning balance (number of shares) | shares	345,395
Granted (number of shares) | shares	91,528
Forfeited (number of shares) | shares	(7,311)
Vested (number of shares) | shares	(126,561)
Affiliate transfers, net (number of shares) | shares	0
Ending balance (number of shares) | shares	303,051
Weighted-Average Grant Date Fair Value
Beginning balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 61.05
Granted, weighted average grant date fair value (dollars per share) | $ / shares	79.23
Forfeited, weighted average grant date fair value (dollars per share) | $ / shares	71.16
Vested, weighted average grant date fair value (dollars per share) | $ / shares	51.08
Affiliate transfers, net, weighted average grant date fair value (dollars per share) | $ / shares	0
Ending balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 69.52
SCE
Restricted Stock Units
Beginning balance (number of shares) | shares	160,788
Granted (number of shares) | shares	47,100
Forfeited (number of shares) | shares	(3,903)
Vested (number of shares) | shares	(64,266)
Affiliate transfers, net (number of shares) | shares	1,699
Ending balance (number of shares) | shares	141,418
Weighted-Average Grant Date Fair Value
Beginning balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 60.80
Granted, weighted average grant date fair value (dollars per share) | $ / shares	79.12
Forfeited, weighted average grant date fair value (dollars per share) | $ / shares	67.65
Vested, weighted average grant date fair value (dollars per share) | $ / shares	53.64
Affiliate transfers, net, weighted average grant date fair value (dollars per share) | $ / shares	60.35
Ending balance, weighted average grant date fair value (dollars per share) | $ / shares	$ 69.96

Investments (Amortized Cost and

Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 4,440	$ 4,242
SCE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	4,440	4,242
SCE | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	2,803	2,784
Fair Value	4,499	4,369
Total Fair Value	4,440	4,242
SCE | Fair Value, Measurements, Recurring | Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	236	319
Fair Value	1,596	1,547
SCE | Fair Value, Measurements, Recurring | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	643	659
Fair Value	768	766
SCE | Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	1,235	1,131
Fair Value	1,319	1,191
SCE | Fair Value, Measurements, Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	579	600
Fair Value	643	659
SCE | Fair Value, Measurements, Recurring | Short-term investments and receivables/payables
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost	110	75
Fair Value	114	79
Repurchase agreements payable	$ 29	$ 114

Investments (Nuclear Decommissi

Investments (Nuclear Decommissioning Trusts) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Unrealized holding gains, net of losses	$ 1,600	$ 1,500
Other-than-temporary impairments	143	170
Deferred income taxes related to unrealized gains	404
Nuclear decommissioning trusts	4,000
Gross realized gains	244	92	$ 326
Gross realized losses	$ (23)	$ (19)	$ (26)

Investments (Acquisitions) (Det

Investments (Acquisitions) (Details) $ in Millions	Dec. 31, 2015USD ($)business	Jun. 30, 2016USD ($)	Dec. 31, 2017USD ($)MWhbusiness
Edison Energy Group
Investment Holdings [Line Items]
After tax charge related to the buy-out of an earn-out provision		$ 13
Edison Energy Group | Series of Individually Immaterial Business Acquisitions
Investment Holdings [Line Items]
Businesses acquired | business	3
Aggregate purchase price	$ 100
Intangible Assets, Net (Including Goodwill)	$ 90
Subsidiary Of SoCore Energy [Member] | Minnesota solar garden development project
Investment Holdings [Line Items]
Aggregate purchase price			$ 19.4
Power generating capacity of acquired projects (in megawatts) | MWh			42
Subsidiary Of SoCore Energy [Member] | Series of Individually Immaterial Business Acquisitions
Investment Holdings [Line Items]
Businesses acquired | business			6
SoCore Energy | Minnesota solar garden development project
Investment Holdings [Line Items]
Reimbursed project-specific interconnection costs			$ 2.6

Regulatory Assets and Liabil105

Regulatory Assets and Liabilities (Textual) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 19, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets	$ 4,914		$ 7,455
SCE
Regulatory Assets [Line Items]
Regulatory assets	$ 4,914		$ 7,455
Regulatory assets, energy derivatives, low range of contract expiration (in years)	3 years
Regulatory assets, energy derivatives, high range of contract expiration (in years)	6 years
Regulatory assets related to deferred income taxes, recovery period, low range (in years)	1 year
Regulatory assets related to deferred income taxes, recovery period, high range (in years)	60 years
Low end of the range of remaining original amortization (in years)	10 years
High end of the range of remaining original amortization (in years)	35 years
Unamortized investments, net of accumulated amortization | SCE
Regulatory Assets [Line Items]
Return rate earned on assets included in rate base (as a percent)	7.90%		7.90%
Regulatory assets	$ 123		$ 80
Unamortized investments, net of accumulated amortization | SCE | Legacy Meters
Regulatory Assets [Line Items]
Return rate earned on assets included in rate base (as a percent)	6.46%		6.46%
San Onofre | SCE
Regulatory Assets [Line Items]
Regulatory assets	$ 72	$ 775	$ 857

Regulatory Assets and Liabil106

Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 19, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Current regulatory assets	$ 703		$ 350
Long-term regulatory assets	4,914		7,455
SCE
Regulatory Assets [Line Items]
Current regulatory assets	703		350
Long-term regulatory assets	4,914		7,455
Total regulatory assets	5,617		7,805
SCE | Regulatory balancing accounts
Regulatory Assets [Line Items]
Current regulatory assets	484		135
Long-term regulatory assets	143		66
SCE | Power contracts and energy derivatives
Regulatory Assets [Line Items]
Current regulatory assets	203		150
Long-term regulatory assets	799		947
SCE | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Current regulatory assets	5		49
Long-term regulatory assets	123		80
SCE | Other
Regulatory Assets [Line Items]
Current regulatory assets	11		16
Long-term regulatory assets	51		7
SCE | Deferred income taxes, net of liabilities
Regulatory Assets [Line Items]
Long-term regulatory assets	3,143		4,478
SCE | Pensions and other postretirement benefits
Regulatory Assets [Line Items]
Long-term regulatory assets	271		710
SCE | San Onofre
Regulatory Assets [Line Items]
Long-term regulatory assets	72	$ 775	857
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Long-term regulatory assets	168		184
SCE | Environmental remediation
Regulatory Assets [Line Items]
Long-term regulatory assets	$ 144		$ 126

Regulatory Assets and Liabil107

Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 1,121	$ 756
Regulatory assets	703	350
Long-term regulatory liabilities	8,614	5,726
SCE
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,121	756
Regulatory assets	703	350
Long-term regulatory liabilities	8,614	5,726
Total regulatory liabilities	9,735	6,482
SCE | Regulatory balancing accounts
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	1,316	1,180
SCE | Energy derivatives
Regulatory Liabilities [Line Items]
Current regulatory liabilities	74	0
SCE | Other
Regulatory Liabilities [Line Items]
Current regulatory liabilities	38	20
Long-term regulatory liabilities	64	60
SCE | Costs of removal
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,741	2,847
SCE | Re-measurement of deferred taxes
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,892	0
SCE | Recoveries in excess of ARO liabilities
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	1,575	1,639
SCE | Other postretirement benefits
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	26	0
Regulatory balancing accounts | SCE
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,009	736
Regulatory assets	$ 484	$ 135

Regulatory Assets and Liabil108

Regulatory Assets and Liabilities (Regulatory Balancing Accounts) (Details) - SCE - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	$ 464	$ (20)
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(197)	(6)
Refunds of excess revenue | Significant components
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(1,698)	(1,715)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(1,145)	(992)
Refunds of excess revenue | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(200)	(426)
Refunds of excess revenue | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(259)	(142)
Refunds of excess revenue | Department of Energy litigation memorandum account
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(156)	(122)
Refunds of excess revenue | Greenhouse gas auction revenue
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(22)	31
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	(205)	(69)
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Net Regulatory Assets Pertaining to Balancing Accounts	$ 22	$ 31

Commitments and Contingencie109

Commitments and Contingencies (Undiscounted Future Minimum Expected Payments for Power Purchase Agreements) (Details) - SCE - Power Purchase Agreements $ in Millions	Dec. 31, 2017USD ($)
Unrecorded Unconditional Purchase Obligation [Line Items]
2,018	$ 2,513
2,019	2,513
2,020	2,614
2,021	2,582
2,022	2,562
Thereafter	27,093
Total future commitments	$ 39,877

Commitments and Contingencie110

Commitments and Contingencies (Power Purchase Agreements Narrative) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecorded Unconditional Purchase Obligation [Line Items]
Costs incurred for power purchase agreements	$ 3,600	$ 3,300	$ 3,200
Signed contracts, not meeting critical contract provisions
Unrecorded Unconditional Purchase Obligation [Line Items]
2,018	29
2,019	109
2,020	231
2,021	312
2,022	301
Thereafter	3,800
Operating Leases Purchase Power Contracts
Unrecorded Unconditional Purchase Obligation [Line Items]
Net operating leases expense	2,300	1,900	1,700
Contingent operating lease expense	1,800	1,400	1,100
Contingent capital lease expense	$ 99	$ 109	$ 1

Commitments and Contingencie111

Commitments and Contingencies (Power Purchase Agreement - Operating and Capital Leases) (Details) - SCE $ in Millions	Dec. 31, 2017USD ($)
Operating Leases
Operating Leases
2,018	$ 335
2,019	262
2,020	234
2,021	198
2,022	174
Thereafter	1,222
Total future commitments	2,425
Capital Leases
Capital Leases
2,018	2
2,019	2
2,020	2
2,021	3
2,022	3
Thereafter	21
Total future commitments	33
Amount representing executory costs	(15)
Amount representing interest	(8)
Net commitments	$ 10

Commitments and Contingencie112

Commitments and Contingencies (Other Lease Commitments) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leased Assets [Line Items]
Operating leases expense	$ 59	$ 68	$ 80
Total
Operating Leased Assets [Line Items]
2,018	48
2,019	37
2,020	27
2,021	20
2,022	15
Thereafter	99
Total future commitments	$ 246

Commitments and Contingencie113

Commitments and Contingencies (Other Commitments) (Details) - SCE - Other contractual obligations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecorded Unconditional Purchase Obligation [Line Items]
2,018	$ 127
2,019	72
2,020	69
2,021	45
2,022	46
Thereafter	345
Total	704
Costs incurred	$ 75	$ 141	$ 182

Commitments and Contingencie114

Commitments and Contingencies (Contingencies) (Details) a in Thousands, $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2017USD ($)acasesstructurefatality	Dec. 31, 2017USD ($)acasesstructurefatality	Jan. 31, 2018structurefatality
December 2017 Wildfires
Loss Contingencies [Line Items]
Acres burned | a	280	280
Structures destroyed | structure	1,063	1,063
Structures damaged | structure	280	280
Fatalities | fatality	2	2
Capital expenditures related to restoration of service	$ 35
Loss Contingency, Number of Plaintiffs | cases		4
Lawsuits | cases	6	6
Montecito Mudslides | Subsequent event
Loss Contingencies [Line Items]
Structures destroyed | structure			135
Structures damaged | structure			324
Fatalities | fatality			21
Additional fatalities presumed | fatality			2
SCE
Loss Contingencies [Line Items]
Wildfire insurance coverage	$ 1,000	$ 1,000
Self insurance retention per wildfire occurrence	10	10
Other general liability insurance coverage	450	450
Threshold for wildfire claims	300	300
The Utilities
Loss Contingencies [Line Items]
Funding commitment for GHG Reduction Program	$ 25	25
Funding obligation reduction		12.5
San Onofre | SCE
Loss Contingencies [Line Items]
Proceeds received		72
Arbitration with Mitsubishi Heavy Industries | San Onofre | SCE
Loss Contingencies [Line Items]
Proceeds received		$ 47

Commitments and Contingencie115

Commitments and Contingencies (San Onofre CPUC Proceedings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 19, 2017
Regulatory Assets [Line Items]
Regulatory assets	$ 4,914	$ 7,455
Impairment and other charges	738	21	$ 5
SCE
Regulatory Assets [Line Items]
Regulatory assets	4,914	7,455
Impairment and other charges	716	0	$ 0
SCE | Utility Shareholder Agreement
Regulatory Assets [Line Items]
Impairment and other charges	143
SCE | San Onofre
Regulatory Assets [Line Items]
Regulatory assets	72	$ 857		$ 775
The Utilities
Regulatory Assets [Line Items]
Funding commitment for GHG Reduction Program	25
Funding obligation reduction	$ 12.5
SDG&E | San Onofre
Regulatory Assets [Line Items]
Regulatory assets				$ 151

Commitments and Contingencie116

Commitments and Contingencies (Schedule of Settlement Agreement) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Total pre-tax charge	$ 738	$ 21	$ 5
SCE
Loss Contingencies [Line Items]
Total pre-tax charge	716	$ 0	$ 0
Total after-tax charge	448
SCE | Utility Shareholder Agreement
Loss Contingencies [Line Items]
Total pre-tax charge	143
SCE | DOE litigation regulatory liability
Loss Contingencies [Line Items]
Total pre-tax charge	(72)
SCE | Arbitration with Mitsubishi Heavy Industries
Loss Contingencies [Line Items]
Total pre-tax charge	(47)
SCE | GHG Reduction Program
Loss Contingencies [Line Items]
Total pre-tax charge	(10)
SCE | San Onofre base regulatory asset
Loss Contingencies [Line Items]
Total pre-tax charge	696
SCE | Other
Loss Contingencies [Line Items]
Total pre-tax charge	$ 6

Commitments and Contingencie117

Commitments and Contingencies (Environmental Remediation) (Details) - SCE $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)site	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Identified material sites (number) | site	20
Minimum estimated liability	$ 1
Recorded estimated minimum liability	$ 150
Immaterial sites (number) | site	16
Environmental remediation regulatory assets	$ 144
Expected recovery from incentive mechanism	$ 49
Expected recovery from incentive mechanism (percent)	90.00%
Recovery through customer rates	$ 95
Recovery through customer rates (percent)	100.00%
Cost may exceed recorded liability, material sites	$ 129
Cost may exceed recorded liability, immaterial sites	$ 8
Clean up (period)	30 years
Expected remediation costs for each of the next four years, low end of range	$ 5
Expected remediation costs for each of the next four years, high end of range	21
Environmental remediation expense	9	$ 4	$ 5
San Onofre
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	93
Material sites
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	146
Immaterial sites | Minimum
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 4

Commitments and Contingencie118

Commitments and Contingencies (Nuclear Insurance) (Details) - Insurance Claims	12 Months Ended
	Dec. 31, 2017USD ($)
Loss Contingencies [Line Items]
Federal loss limit, bodily injury and property damage from nuclear incident	$ 13,400,000,000
SCE and other owners of San Onofre and Palo Verde | San Onofre and Palo Verde
Loss Contingencies [Line Items]
Maximum private primary insurance	450,000,000
ANI Facility Form coverage aggregate limit	450,000,000
Minimum federal requirement of nuclear property insurance	1,060,000,000
SCE
Loss Contingencies [Line Items]
Maximum assessment per each nuclear incident	255,000,000
Maximum yearly assessment per nuclear incident	38,000,000
Limit on assessment of retrospective premium adjustments, per year, approximate	$ 52,000,000

Commitments and Contingencie119

Commitments and Contingencies (Spent Nuclear Fuel) (Details) - USD ($) $ in Millions	1 Months Ended
	Apr. 30, 2016	Jun. 30, 2010	Oct. 30, 2017	Feb. 28, 2017	Sep. 30, 2016
Loss Contingencies [Line Items]
Claim to recover damages incurred					$ 56
SCE and other owners of San Onofre and Palo Verde
Loss Contingencies [Line Items]
Damages sought		$ 142
Litigation settlement	$ 162
Claim to recover damages incurred				$ 43
SCE
Loss Contingencies [Line Items]
Damages sought		$ 112
Litigation settlement	$ 124
Claim to recover damages incurred			$ 59	$ 34

Preferred and Preference Sto120

Preferred and Preference Stock of Utility (Textual) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Preferred and Preference Stock
Preferred and Preference Stock of Utility
Dividends payable	$ 12	$ 12	$ 14
SCE | Cumulative preferred stock $100 par value
Preferred and Preference Stock of Utility
Preferred stock, par value (in dollars per share)	$ 100
Preferred stock, shares authorized	12,000,000
SCE | Cumulative preferred stock $25 par value
Preferred and Preference Stock of Utility
Preferred stock, par value (in dollars per share)	$ 25
Preferred stock, shares authorized	24,000,000
SCE | No par value
Preferred and Preference Stock of Utility
Preferred stock, shares authorized	50,000,000
SCE | Preferred and Preference Stock
Preferred and Preference Stock of Utility
Preferred stock, shares issued	0	0	0
Preferred stock, shares redeemed	0	0	0
Dividends payable	$ 12	$ 12	$ 14
SCE | 5.00% Series L (cumulative)
Preferred and Preference Stock of Utility
Issuance of preference stock, during the period, value	$ 475

Preferred and Preference Sto121

Preferred and Preference Stock of Utility (Schedule of Preferred and Preference Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Preferred and Preference Stock of Utility
Edison International's preferred and preference stock of utility	$ 2,193	$ 2,191
SCE
Preferred and Preference Stock of Utility
Edison International's preferred and preference stock of utility	$ 2,245	2,245
SCE | 4.08% Series
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	4.08%
Shares Outstanding	650,000
Redemption Price (in dollars per share)	$ 25.5
Preferred stock before issuance costs	$ 16	16
Preferred stock, par value (in dollars per share)	$ 25
SCE | 4.24% Series
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	4.24%
Shares Outstanding	1,200,000
Redemption Price (in dollars per share)	$ 25.8
Preferred stock before issuance costs	$ 30	30
Preferred stock, par value (in dollars per share)	$ 25
SCE | 4.32% Series
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	4.32%
Shares Outstanding	1,653,429
Redemption Price (in dollars per share)	$ 28.75
Preferred stock before issuance costs	$ 41	41
Preferred stock, par value (in dollars per share)	$ 25
SCE | 4.78% Series
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	4.78%
Shares Outstanding	1,296,769
Redemption Price (in dollars per share)	$ 25.8
Preferred stock before issuance costs	$ 33	33
Preferred stock, par value (in dollars per share)	$ 25
SCE | Preference stock
Preferred and Preference Stock of Utility
Preferred stock before issuance costs	$ 2,245	2,245
Less issuance costs	(52)	(54)
Edison International's preferred and preference stock of utility	$ 2,193	2,191
SCE | 6.25% Series E (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	6.25%
Shares Outstanding	350,000
Redemption Price (in dollars per share)	$ 1,000
Preferred stock before issuance costs	$ 350	350
SCE | 5.625% Series F (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	5.625%
Shares Outstanding	190,004
Redemption Price (in dollars per share)	$ 2,500
Preferred stock before issuance costs	$ 0	475
SCE | 5.10% Series G (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	5.10%
Shares Outstanding	160,004
Redemption Price (in dollars per share)	$ 2,500
Preferred stock before issuance costs	$ 400	400
SCE | 5.75% Series H (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	5.75%
Shares Outstanding	110,004
Redemption Price (in dollars per share)	$ 2,500
Preferred stock before issuance costs	$ 275	275
SCE | 5.375% Series J (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	5.375%
Shares Outstanding	130,004
Redemption Price (in dollars per share)	$ 2,500
Preferred stock before issuance costs	$ 325	325
SCE | 5.45% Series K (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	5.45%
Shares Outstanding	120,004
Redemption Price (in dollars per share)	$ 2,500
Preferred stock before issuance costs	$ 300	300
SCE | 5.00% Series L (cumulative)
Preferred and Preference Stock of Utility
Preferred Stock, dividend rate, (as a percent)	5.00%
Shares Outstanding	190,004
Redemption Price (in dollars per share)	$ 2,500
Preferred stock before issuance costs	$ 475	$ 0

Accumulated Other Comprehens122

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and PBOP – net gain (loss):
Other	$ 0	$ 1	$ 0
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(53)	(56)
Pension and PBOP – net gain (loss):
Ending balance	(43)	(53)	(56)
Accumulated Defined Benefit Plans Adjustment
Pension and PBOP – net gain (loss):
Other comprehensive income (loss) before reclassifications	3	(4)
Reclassified from accumulated other comprehensive loss	7	6
Other	0	1
Change	10	3
SCE
Pension and PBOP – net gain (loss):
Other	0	1	0
SCE | Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(20)	(22)
Pension and PBOP – net gain (loss):
Ending balance	(19)	(20)	$ (22)
SCE | Accumulated Defined Benefit Plans Adjustment
Pension and PBOP – net gain (loss):
Other comprehensive income (loss) before reclassifications	(2)	(2)
Reclassified from accumulated other comprehensive loss	3	3
Other	0	1
Change	$ 1	$ 2

Interest and Other Income an123

Interest and Other Income and Other Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SCE interest and other income:
Total Edison International interest and other income	$ 146	$ 123	$ 174
SCE other expenses:
Total Edison International other expenses	(51)	(44)	(59)
Edison International Parent and Other
SCE interest and other income:
Other income of Edison International Parent and Other	1	0	51
SCE other expenses:
Other expenses of Edison International Parent and Other	(3)	0	0
SCE
SCE interest and other income:
Equity allowance for funds used during construction	87	74	87
Increase in cash surrender value of life insurance policies and life insurance benefits	42	39	26
Interest income	7	3	4
Other	9	7	6
Total SCE interest and other income	145	123	123
Total Edison International interest and other income	145	123	123
SCE other expenses:
Civic, political and related activities and donations	(34)	(32)	(35)
Other	(14)	(12)	(24)
Total SCE other expenses	(48)	(44)	(59)
Total Edison International other expenses	$ (48)	$ (44)	$ (59)

Supplemental Cash Flows Info124

Supplemental Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash payments for interest and taxes:
Interest, net of amounts capitalized	$ 548	$ 504	$ 512
Tax payments, net of refunds	1	18	1
Details of debt exchange:
Pollution-control bonds redeemed (2.875%)	0	0	(203)
Pollution-control bonds issued (1.875%)	$ 0	$ 0	$ 203
2.875% Pollution-Control Bonds
Details of debt exchange:
Interest rate on converted debt	2.875%	2.875%	2.875%
1.875% Pollution-Control Bonds Due in 2029
Details of debt exchange:
Interest rate on converted debt	1.875%	1.875%	1.875%
Common Stock
Non-cash financing and investing activities:
Dividends declared but not paid	$ 197	$ 177	$ 156
Preference stock
Non-cash financing and investing activities:
Dividends declared but not paid	12	12	14
SCE
Cash payments for interest and taxes:
Interest, net of amounts capitalized	509	475	478
Tax payments, net of refunds	2	78	144
Details of debt exchange:
Pollution-control bonds redeemed (2.875%)	0	0	(203)
Pollution-control bonds issued (1.875%)	0	0	203
Accrued capital expenditures	$ 652	$ 540	543
Reduction in lease obligation			$ 147
SCE | 2.875% Pollution-Control Bonds
Details of debt exchange:
Interest rate on converted debt	2.875%	2.875%	2.875%
SCE | 1.875% Pollution-Control Bonds Due in 2029
Details of debt exchange:
Interest rate on converted debt	1.875%	1.875%	1.875%
SCE | Common Stock
Non-cash financing and investing activities:
Dividends declared but not paid	$ 212	$ 0	$ 0
SCE | Preference stock
Non-cash financing and investing activities:
Dividends declared but not paid	$ 12	$ 12	$ 14

Quarterly Financial Data (Un125

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Data [Line Items]
Total operating revenue	$ 3,220	$ 3,672	$ 2,965	$ 2,463	$ 2,884	$ 3,767	$ 2,777	$ 2,440	$ 12,320	$ 11,869	$ 11,524
Operating income (loss)	(16)	561	469	479	566	695	381	448	1,493	2,092	2,008
Net income (loss)									668	1,425	1,117
Income (loss) from continuing operations	(534)	501	309	392	347	451	310	305	668	1,413	1,082
Income (loss) from discontinued operations, net	0	0	0	0	13	0	(2)	1	0	12	35
Net income attributable to common shareholders	$ (545)	$ 470	$ 278	$ 362	$ 329	$ 421	$ 280	$ 281	$ 565	$ 1,311	$ 1,020
Basic earnings per share – continuing operations:
Continuing operations (in dollars per share)	$ (1.67)	$ 1.44	$ 0.85	$ 1.11	$ 0.97	$ 1.29	$ 0.87	$ 0.86	$ 1.73	$ 3.99	$ 3.02
Discontinued operations (in dollars per share)	0	0	0	0	0.04	0	(0.01)	0	0	0.03	0.11
Total (in dollars per share)	(1.67)	1.44	0.85	1.11	1.01	1.29	0.86	0.86	1.73	4.02	3.13
Diluted earnings per share – continuing operations:
Continuing operations (in dollars per share)	(1.66)	1.43	0.85	1.10	0.96	1.27	0.86	0.85	1.72	3.94	2.99
Diluted earnings (loss) per share – discontinued operations (in dollars per share)	0	0	0	0	0.04	0	(0.01)	0	0	0.03	0.11
Total (in dollars per share)	(1.66)	1.43	0.85	1.10	1	1.27	0.85	0.85	1.72	3.97	3.10
Dividends declared per common share (in dollars per share)	0.6050	0.5425	0.5425	0.5425	0.5425	0.4800	0.4800	0.4800	2.2325	1.9825	$ 1.7325
Common stock prices:
High (in dollars per share)	83.38	81.58	82.82	81.33	73.81	78.72	77.71	72.34	83.38	78.72
Low (in dollars per share)	62.67	76.38	77.21	70.57	67.44	71.31	67.71	57.97	62.67	57.97
Close (in dollars per share)	$ 63.24	$ 77.17	$ 78.19	$ 79.61	$ 71.99	$ 72.25	$ 77.67	$ 71.89	$ 63.24	$ 71.99
Impairment and other charges									$ 738	$ 21	$ 5
Edison International Parent and Other
Common stock prices:
Write-down for re-measurement of deferred taxes as a result of the Tax Cuts and Jobs Act	$ 433
SCE
Quarterly Financial Data [Line Items]
Total operating revenue	3,193	$ 3,652	$ 2,953	$ 2,456	$ 2,874	$ 3,752	$ 2,768	$ 2,435	12,254	11,830	11,485
Operating income (loss)	(4)	578	517	507	594	721	429	472	1,598	2,217	2,080
Net income (loss)	(79)	497	338	380	359	466	349	325	1,136	1,499	1,111
Net income attributable to common shareholders	(109)	465	307	349	328	435	318	295	1,012	1,376	998
Common stock prices:
Common dividends declared	212	$ 191	$ 191	$ 191	$ 191	$ 170	$ 170	$ 170	785	701
Impairment and other charges									$ 716	$ 0	$ 0
SCE | Revised San Onofre settlement agreement
Common stock prices:
Impairment and other charges	716
Impairment and other charges, net of tax	$ 448

Schedule I - Condensed Finan126

Schedule I - Condensed Financial Information of Parent (Details)	1 Months Ended		3 Months Ended								12 Months Ended
	Jan. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)	Aug. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Assets:
Cash and cash equivalents	$ 1,091,000,000	$ 1,091,000,000	$ 1,091,000,000			$ 96,000,000	$ 96,000,000			$ 161,000,000	$ 96,000,000	$ 161,000,000	$ 132,000,000	$ 1,091,000,000		$ 96,000,000	$ 161,000,000	$ 132,000,000
Other current assets														202,000,000		177,000,000
Total current assets														3,729,000,000		2,123,000,000
Other long-term assets														374,000,000		416,000,000
Total assets														52,580,000,000		51,319,000,000
Liabilities and equity:
Short-term debt														2,393,000,000		1,307,000,000
Current portion of long-term debt														481,000,000		981,000,000
Other current liabilities														1,265,000,000		991,000,000
Total current liabilities														7,068,000,000		5,912,000,000
Long-term debt														11,642,000,000		10,175,000,000
Total equity														13,866,000,000		14,187,000,000	13,388,000,000	12,982,000,000
Total liabilities and equity														52,580,000,000		$ 51,319,000,000
Condensed Statements of Income:
Interest income from affiliates			3,220,000,000	$ 3,672,000,000	$ 2,965,000,000	2,463,000,000	2,884,000,000	$ 3,767,000,000	$ 2,777,000,000	2,440,000,000	12,320,000,000	11,869,000,000	11,524,000,000
Operating expenses and interest expense											10,827,000,000	9,777,000,000	9,516,000,000
Operating income			(16,000,000)	561,000,000	469,000,000	479,000,000	566,000,000	695,000,000	381,000,000	448,000,000	1,493,000,000	2,092,000,000	2,008,000,000
Income tax expense (benefit)											281,000,000	177,000,000	486,000,000
Income from continuing operations			(534,000,000)	501,000,000	309,000,000	392,000,000	347,000,000	451,000,000	310,000,000	305,000,000	668,000,000	1,413,000,000	1,082,000,000
Income from discontinued operations, net of tax			0	0	0	0	13,000,000	0	(2,000,000)	1,000,000	0	12,000,000	35,000,000
Condensed Statements of Comprehensive Income
Other comprehensive income, net of tax											10,000,000	3,000,000	2,000,000
Comprehensive income											575,000,000	1,314,000,000	1,022,000,000
Condensed Statements of Cash Flows:
Net cash provided by operating activities											3,587,000,000	3,256,000,000	4,509,000,000
Cash flows from financing activities:
Long-term debt issued											2,233,000,000	397,000,000	1,420,000,000
Repayments of Long-term Debt											(1,285,000,000)	(220,000,000)	(762,000,000)
Short-term debt financing, net											1,084,000,000	611,000,000	(572,000,000)
Payments for stock-based compensation											(393,000,000)	(237,000,000)	(197,000,000)
Receipts from stock option exercises											215,000,000	135,000,000	128,000,000
Dividends paid											(707,000,000)	(626,000,000)	(544,000,000)
Net cash provided by (used in) financing activities											1,007,000,000	95,000,000	(588,000,000)
Net cash used in investing activities											(3,599,000,000)	(3,416,000,000)	(3,892,000,000)
Net increase (decrease) in cash and cash equivalents											995,000,000	(65,000,000)	29,000,000
Cash and cash equivalents, beginning of year	1,091,000,000					96,000,000				161,000,000	96,000,000	161,000,000	132,000,000
Cash and cash equivalents, end of year		1,091,000,000	1,091,000,000				96,000,000				1,091,000,000	96,000,000	161,000,000
Senior Notes Due 2017
Debt and Credit Agreements
Interest rate on debt (as a percent)																3.75%
Multi-year credit facilities
Debt and Credit Agreements
Commitment														1,250,000,000
Outstanding borrowings														(1,139,000,000)		$ (538,000,000)
Amount available														111,000,000
Weighted average interest rate (as a percent)																0.97%
Senior notes | 2.125% Senior notes due 2020
Debt and Credit Agreements
Debt, face amount						$ 400,000,000
Interest rate on debt (as a percent)						2.125%
Senior notes | 2.40% Senior notes due 2022
Debt and Credit Agreements
Debt, face amount															$ 400,000,000
Interest rate on debt (as a percent)															2.40%
Senior notes | 2.95% Senior notes due 2023
Debt and Credit Agreements
Debt, face amount														$ 400,000,000
Interest rate on debt (as a percent)														2.95%
Edison International Parent and Other
Assets:
Cash and cash equivalents	524,000,000	524,000,000	524,000,000			$ 6,000,000	6,000,000			7,000,000	6,000,000	7,000,000	8,000,000	$ 524,000,000		$ 6,000,000	7,000,000	8,000,000
Other current assets														340,000,000		261,000,000
Total current assets														864,000,000		267,000,000
Investments in subsidiaries														13,659,000,000		13,459,000,000
Deferred income taxes														500,000,000		646,000,000
Other long-term assets														91,000,000		108,000,000
Total assets														15,114,000,000		14,480,000,000
Liabilities and equity:
Short-term debt														1,139,000,000		539,000,000
Current portion of long-term debt														0		400,000,000
Other current liabilities														467,000,000		484,000,000
Total current liabilities														1,606,000,000		1,423,000,000
Long-term debt														1,193,000,000		397,000,000
Other long-term liabilities														644,000,000		664,000,000
Total equity														11,671,000,000		11,996,000,000
Total liabilities and equity														15,114,000,000		14,480,000,000
Condensed Statements of Income:
Interest income from affiliates											0	6,000,000	3,000,000
Operating expenses and interest expense											92,000,000	86,000,000	78,000,000
Operating income											(92,000,000)	(80,000,000)	(75,000,000)
Equity in earnings of subsidiaries											739,000,000	1,337,000,000	1,025,000,000
Income before income taxes											647,000,000	1,257,000,000	950,000,000
Income tax expense (benefit)											82,000,000	(42,000,000)	(35,000,000)
Income from continuing operations											565,000,000	1,299,000,000	985,000,000
Income from discontinued operations, net of tax											0	12,000,000	35,000,000
Net income											565,000,000	1,311,000,000	1,020,000,000
Condensed Statements of Comprehensive Income
Net income											565,000,000	1,311,000,000	1,020,000,000
Other comprehensive income, net of tax											10,000,000	3,000,000	2,000,000
Comprehensive income											575,000,000	1,314,000,000	1,022,000,000
Condensed Statements of Cash Flows:
Net cash provided by operating activities											462,000,000	493,000,000	641,000,000
Cash flows from financing activities:
Long-term debt issued											798,000,000	400,000,000	0
Long-term debt issuance costs											(5,000,000)	(3,000,000)	0
Repayments of Long-term Debt											(400,000,000)	0	0
Payable due to affiliates											8,000,000	34,000,000	54,000,000
Short-term debt financing, net											600,000,000	(108,000,000)	26,000,000
Payments for stock-based compensation											(260,000,000)	(95,000,000)	(114,000,000)
Receipts from stock option exercises											144,000,000	51,000,000	72,000,000
Dividends paid											(707,000,000)	(626,000,000)	(544,000,000)
Net cash provided by (used in) financing activities											178,000,000	(347,000,000)	(506,000,000)
Capital contributions to affiliate											(122,000,000)	(147,000,000)	(30,000,000)
Loans to affiliate											0	0	(106,000,000)
Net cash used in investing activities											(122,000,000)	(147,000,000)	(136,000,000)
Net increase (decrease) in cash and cash equivalents											518,000,000	(1,000,000)	(1,000,000)
Cash and cash equivalents, beginning of year	524,000,000					6,000,000				7,000,000	6,000,000	7,000,000	8,000,000
Cash and cash equivalents, end of year		524,000,000	524,000,000				6,000,000				524,000,000	6,000,000	7,000,000
Basis of Presentation
Cash dividends received from consolidated subsidiaries											573,000,000	701,000,000	758,000,000
Related Party Transactions
Current receivables due from affiliates														256,000,000		262,000,000
Current payables due to affiliates														235,000,000		221,000,000
Long-term receivables due from affiliate														81,000,000		103,000,000
Long-term payables due to affiliates														$ 200,000,000		$ 243,000,000
Edison International Parent and Other | Senior Notes Due 2017
Debt and Credit Agreements
Interest rate on debt (as a percent)																3.75%
Senior notes																$ 400,000,000
Edison International Parent and Other | Credit Facility July 2020
Debt and Credit Agreements
Commitment					1,250,000,000
Edison International Parent and Other | Revolving credit facility maturing in July 2018
Debt and Credit Agreements
Covenant requirement, consolidated debt to total capitalization, ratio														0.65
Consolidated debt to total capitalization, ratio														0.51
Edison International Parent and Other | SCE
Related Party Transactions
Expenses from services provided by SCE											3,000,000	3,000,000	3,000,000
Interest expense from loans due to affiliates											5,000,000	3,000,000	6,000,000
Edison International Parent and Other
Liabilities and equity:
Current portion of long-term debt														$ 2,000,000		402,000,000
Long-term debt														1,214,000,000		421,000,000
SCE
Assets:
Cash and cash equivalents	515,000,000	515,000,000	515,000,000			39,000,000	39,000,000			26,000,000	39,000,000	26,000,000	38,000,000	515,000,000		39,000,000	26,000,000	38,000,000
Other current assets														160,000,000		148,000,000
Total current assets														3,087,000,000		2,031,000,000
Other long-term assets														237,000,000		232,000,000
Total assets														51,515,000,000		50,891,000,000
Liabilities and equity:
Short-term debt														1,238,000,000		769,000,000
Current portion of long-term debt														479,000,000		579,000,000
Other current liabilities														1,224,000,000		729,000,000
Total current liabilities														5,887,000,000		4,707,000,000
Long-term debt														10,428,000,000		9,754,000,000
Total equity														14,672,000,000		14,483,000,000	13,672,000,000	$ 13,282,000,000
Total liabilities and equity														51,515,000,000		50,891,000,000
Condensed Statements of Income:
Interest income from affiliates			3,193,000,000	3,652,000,000	2,953,000,000	2,456,000,000	2,874,000,000	3,752,000,000	2,768,000,000	2,435,000,000	12,254,000,000	11,830,000,000	11,485,000,000
Operating expenses and interest expense											10,656,000,000	9,613,000,000	9,405,000,000
Operating income			(4,000,000)	$ 578,000,000	$ 517,000,000	507,000,000	594,000,000	$ 721,000,000	$ 429,000,000	472,000,000	1,598,000,000	2,217,000,000	2,080,000,000
Income tax expense (benefit)											(30,000,000)	256,000,000	507,000,000
Condensed Statements of Comprehensive Income
Other comprehensive income, net of tax											1,000,000	2,000,000	6,000,000
Condensed Statements of Cash Flows:
Net cash provided by operating activities											3,725,000,000	3,523,000,000	4,624,000,000
Cash flows from financing activities:
Long-term debt issued											1,445,000,000	0	1,413,000,000
Repayments of Long-term Debt											(882,000,000)	(217,000,000)	(761,000,000)
Short-term debt financing, net											469,000,000	719,000,000	(619,000,000)
Payments for stock-based compensation											(86,000,000)	(127,000,000)	(78,000,000)
Receipts from stock option exercises											48,000,000	76,000,000	68,000,000
Dividends paid											(697,000,000)	(824,000,000)	(874,000,000)
Net cash provided by (used in) financing activities											243,000,000	(219,000,000)	(812,000,000)
Net cash used in investing activities											(3,492,000,000)	(3,291,000,000)	(3,824,000,000)
Net increase (decrease) in cash and cash equivalents											476,000,000	13,000,000	(12,000,000)
Cash and cash equivalents, beginning of year	515,000,000					$ 39,000,000				$ 26,000,000	39,000,000	26,000,000	38,000,000
Cash and cash equivalents, end of year		515,000,000	$ 515,000,000				$ 39,000,000				$ 515,000,000	$ 39,000,000	$ 26,000,000
Basis of Presentation
Minimum percentage of weighted-average common equity component authorization, set by CPUC (as a percent)											48.00%
Weighted-average common equity component authorization, set by CPUC remaining over number of months (in months)											13 months
After-tax charge excused from capital structure											$ 448,000,000
Period for calculation of weighted average common equity component (months)											13 months
Weighted-average common equity component of total capitalization (as a percent)											50.00%
Capacity to pay additional dividends											$ 511,000,000
Restriction on net assets														$ 14,200,000,000
Debt and Credit Agreements
Weighted average interest rate (as a percent)														2.56%
SCE | Pro forma
Basis of Presentation
Weighted-average common equity component authorization, set by CPUC remaining over number of months (in months)											13 months
Period for calculation of weighted average common equity component (months)											13 months
Weighted-average common equity component of total capitalization (as a percent)											50.10%
SCE | Multi-year credit facilities
Debt and Credit Agreements
Commitment														$ 2,750,000,000
Outstanding borrowings														(1,238,000,000)
Amount available														$ 1,413,000,000
Weighted average interest rate (as a percent)														2.46%
Line of credit
Debt and Credit Agreements
Borrowings from credit facility		500,000,000
Line of credit | SCE
Debt and Credit Agreements
Borrowings from credit facility		$ 500,000,000
Subsequent event | Edison International Parent and Other | Term Loan Agreement
Debt and Credit Agreements
Debt, face amount	$ 500,000,000
Basis points	60.00%
Subsequent event | Line of credit
Debt and Credit Agreements
Repayment on borrowings	$ 500,000,000
Subsequent event | Line of credit | SCE
Debt and Credit Agreements
Repayment on borrowings	$ 500,000,000
Related-party note receivable converted into capital contribution
Related Party Transactions
Conversion of note											$ 184,000,000
Commercial paper | Multi-year credit facilities
Debt and Credit Agreements
Outstanding borrowings														$ (639,000,000)
Weighted average interest rate (as a percent)														1.70%
Commercial paper | SCE | Multi-year credit facilities
Debt and Credit Agreements
Outstanding borrowings																$ (769,000,000)
Weighted average interest rate (as a percent)														1.75%		0.90%
Common Stock
Basis of Presentation
Dividends declared but not paid														$ 197,000,000		$ 177,000,000	156,000,000
Common Stock | SCE
Basis of Presentation
Dividends declared but not paid														$ 212,000,000		$ 0	$ 0

Schedule II - Valuation and 127

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	$ 61.8	$ 61.7	$ 72.2
Charged to Costs and Expenses	26.4	33.6	41.9
Charged to Other Accounts	0	0	0
Deductions	34.3	33.5	52.4
Balance at End of Period	53.9	61.8	61.7
Customers
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	41.2	46.2	48.9
Charged to Costs and Expenses	12.9	17.7	23.9
Charged to Other Accounts	0	0	0
Deductions	17.5	22.7	26.6
Balance at End of Period	36.6	41.2	46.2
All others
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	20.6	15.5	23.3
Charged to Costs and Expenses	13.5	15.9	18
Charged to Other Accounts	0	0	0
Deductions	16.8	10.8	25.8
Balance at End of Period	17.3	20.6	15.5
Tax valuation allowance
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	24	32	29
Charged to Costs and Expenses	0	0	3
Charged to Other Accounts	4	0	0
Deductions	0	8	0
Balance at End of Period	28	24	32
Valuation Allowances and Reserves, Write-offs		8
Southern California Edison Company
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	61.1	61.7	67.6
Charged to Costs and Expenses	26.4	32.9	41.9
Charged to Other Accounts	0	0	0
Deductions	34.2	33.5	47.8
Balance at End of Period	53.3	61.1	61.7
Southern California Edison Company | Customers
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	40.5	46.2	48.9
Charged to Costs and Expenses	12.9	17	23.9
Charged to Other Accounts	0	0	0
Deductions	17.4	22.7	26.6
Balance at End of Period	36	40.5	46.2
Southern California Edison Company | All others
Movement in Valuation and Qualifying Accounts
Balance at Beginning of Period	20.6	15.5	18.7
Charged to Costs and Expenses	13.5	15.9	18
Charged to Other Accounts	0	0	0
Deductions	16.8	10.8	21.2
Balance at End of Period	$ 17.3	$ 20.6	$ 15.5