Consolidated Statements of Changes in Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			$ 13,866	$ 14,187	$ 14,187
Net income			1,087	1,204
Net income	$ 544	$ 501	1,084	1,202
Other comprehensive income			6
Other comprehensive income	2	0	1	5
Cumulative effect of accounting changes			5
Contributions from tax equity investor			24
Dividends declared on common stock			(591)	(530)
Dividends to noncontrolling interests			(91)	(94)
Stock-based compensation			(17)	(165)
Noncash stock-based compensation			15	15
Deconsolidation of SoCore Energy			(15)
Issuance of preference stock				463
Redemption of preference stock				(475)
Balance, at the end of the period	$ 14,289	$ 14,610	$ 14,289	$ 14,610	13,866
Dividends declared per common share (in dollars per share)	$ 0.6050	$ 0.5425	$ 1.815	$ 1.6275
Common Stock Including Additional Paid in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			$ 2,526	$ 2,505	2,505
Net income			0	0
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			0
Dividends declared on common stock			0	0
Dividends to noncontrolling interests			0	0
Stock-based compensation			0	0
Noncash stock-based compensation			15	15
Deconsolidation of SoCore Energy			0
Issuance of preference stock				0
Redemption of preference stock				0
Balance, at the end of the period	$ 2,541	$ 2,520	2,541	2,520	2,526
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			(43)	(53)	(53)
Net income			0	0
Other comprehensive income			6
Other comprehensive income				5
Cumulative effect of accounting changes			(5)
Dividends declared on common stock			0	0
Dividends to noncontrolling interests			0	0
Stock-based compensation			0	0
Noncash stock-based compensation			0	0
Deconsolidation of SoCore Energy			0
Issuance of preference stock				0
Redemption of preference stock				0
Balance, at the end of the period	(42)	(48)	(42)	(48)	(43)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			9,188	9,544	9,544
Net income			1,007	1,110
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			10
Dividends declared on common stock			(591)	(530)
Dividends to noncontrolling interests			0	0
Stock-based compensation			(17)	(165)
Noncash stock-based compensation			0	0
Deconsolidation of SoCore Energy			0
Issuance of preference stock				0
Redemption of preference stock				(15)
Balance, at the end of the period	9,597	9,944	9,597	9,944	9,188
Subtotal
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			11,671	11,996	11,996
Net income			1,007	1,110
Other comprehensive income			6
Other comprehensive income				5
Cumulative effect of accounting changes			5
Dividends declared on common stock			(591)	(530)
Dividends to noncontrolling interests			0	0
Stock-based compensation			(17)	(165)
Noncash stock-based compensation			15	15
Deconsolidation of SoCore Energy			0
Issuance of preference stock				0
Redemption of preference stock				(15)
Balance, at the end of the period	12,096	12,416	12,096	12,416	11,671
Noncontrolling Interests, Other
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			2
Net income			(11)
Other comprehensive income			0
Cumulative effect of accounting changes			0
Contributions from tax equity investor			24
Dividends declared on common stock			0
Dividends to noncontrolling interests			0
Stock-based compensation			0
Noncash stock-based compensation			0
Deconsolidation of SoCore Energy			(15)
Balance, at the end of the period	0		0		2
Noncontrolling Interests, Preferred and Preference Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			2,193	2,191	2,191
Net income			91	94
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			0
Dividends declared on common stock			0	0
Dividends to noncontrolling interests			(91)	(94)
Stock-based compensation			0	0
Noncash stock-based compensation			0	0
Deconsolidation of SoCore Energy			0
Issuance of preference stock				463
Redemption of preference stock				(460)
Balance, at the end of the period	2,193	2,194	2,193	2,194	2,193
Southern California Edison
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			14,672	14,483	14,483
Net income	567	497	1,210	1,215
Other comprehensive income			4
Other comprehensive income	1	0	(1)	2
Cumulative effect of accounting changes			0
Dividends declared on common stock			(576)	(573)
Dividends declared on preferred and preference stock			(91)	(94)
Stock-based compensation			(9)	(36)
Noncash stock-based compensation			7	8
Issuance of preference stock				463
Redemption of preference stock				(475)
Balance, at the end of the period	15,217	14,993	15,217	14,993	14,672
Southern California Edison | Common stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			2,168	2,168	2,168
Net income			0	0
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			0
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation			0	0
Noncash stock-based compensation			0	0
Issuance of preference stock				0
Redemption of preference stock				0
Balance, at the end of the period	2,168	2,168	2,168	2,168	2,168
Southern California Edison | Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			671	657	657
Net income			0	0
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			0
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation			0	0
Noncash stock-based compensation			7	8
Issuance of preference stock				(12)
Redemption of preference stock				15
Balance, at the end of the period	678	668	678	668	671
Southern California Edison | Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			(19)	(20)	(20)
Net income			0	0
Other comprehensive income			4
Other comprehensive income				2
Cumulative effect of accounting changes			(5)
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation			0	0
Noncash stock-based compensation			0	0
Issuance of preference stock				0
Redemption of preference stock				0
Balance, at the end of the period	(20)	(18)	(20)	(18)	(19)
Southern California Edison | Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			9,607	9,433	9,433
Net income			1,210	1,215
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			5
Dividends declared on common stock			(576)	(573)
Dividends declared on preferred and preference stock			(91)	(94)
Stock-based compensation			(9)	(36)
Noncash stock-based compensation			0	0
Issuance of preference stock				0
Redemption of preference stock				(15)
Balance, at the end of the period	10,146	9,930	10,146	9,930	9,607
Southern California Edison | Preferred and Preference Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period			2,245	2,245	2,245
Net income			0	0
Other comprehensive income			0
Other comprehensive income				0
Cumulative effect of accounting changes			0
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation			0	0
Noncash stock-based compensation			0	0
Issuance of preference stock				475
Redemption of preference stock				(475)
Balance, at the end of the period	$ 2,245	$ 2,245	$ 2,245	$ 2,245	$ 2,245