Income Taxes (Deferred Tax Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosures:
Cash Contribution From Parent	$ 12	[1]
Deferred tax assets
Derivative instruments	15		49
Net operating loss carryforwards	1,202		841
Accrued charges and liabilities	232		234
Total deferred tax assets, gross	1,786		1,384
Valuation allowance	(752)		(444)
Net deferred tax assets	1,034		940
Production tax and other credit carryforwards	332		254
Other	5		6
Deferred tax liabilities
Property, plant and equipment - basis differences	1,069		989
Deferred investment tax credit	4		4
State taxes	19		28
Total	1,092		1,021
Deferred tax assets and (liabilities), net	(58)		(81)
Classification of net accumulated deferred income taxes
Deferred taxes and tax credits	58		81
Change in valuation allowance on deferred tax asset	308
Non-cash distribution to parent	(185)		(222)
Other long-term assets	103		128
Payables to affiliates	16		34
Other Liabilities, Noncurrent	377		528
Non-cash Contribution From Parent	25	[1],[2]	0	0
Federal
Classification of net accumulated deferred income taxes
Tax credit carryforwards	332
Federal | Expiring in 2031 and 2032
Classification of net accumulated deferred income taxes
Net operating loss carryforwards	3,226
Federal | Expiring Between 2029 and 2032
Classification of net accumulated deferred income taxes
Tax credit carryforwards	317
State | Expiring Between 2022 and 2032
Classification of net accumulated deferred income taxes
Net operating loss carryforwards	2,106
Midwest Generation LLC [Member]
Deferred tax assets
State taxes	3		0
Deferred income	2		2
Derivative instruments	6		24
Impairment of loan to affiliate - tax	539		539
Property, plant and equipment - basis differences	107		0
Net operating loss carryforwards	88		0
Accrued charges and liabilities	22		16
Total deferred tax assets, gross	767		581
Valuation allowance	(767)		(533)
Net deferred tax assets	0		48
Deferred tax liabilities
Property, plant and equipment - basis differences	0		45
State taxes	0		3
Total	0		48
Deferred tax assets and (liabilities), net	0		0
Classification of net accumulated deferred income taxes
Change in valuation allowance on deferred tax asset	234
Valuation Allowance, Amount	167
Other long-term assets	10		28
Payables to affiliates	6		3
Other Liabilities, Noncurrent	113		192
Midwest Generation LLC [Member] | Federal | Expiring in 2031 and 2032
Classification of net accumulated deferred income taxes
Net operating loss carryforwards	517
Midwest Generation LLC [Member] | State | Expiring Between 2025 and 2032
Classification of net accumulated deferred income taxes
Net operating loss carryforwards	341
Accumulated other comprehensive loss
Deferred tax assets
Valuation allowance			(6)
Accumulated other comprehensive loss | Midwest Generation LLC [Member]
Deferred tax assets
Valuation allowance			(12)
Hypothetical Tax Return | Midwest Generation LLC [Member]
Classification of net accumulated deferred income taxes
Non-cash distribution to parent			(106)
Provision (Benefit) for Income Taxes
Classification of net accumulated deferred income taxes
Change in valuation allowance on deferred tax asset			438
Provision (Benefit) for Income Taxes | Midwest Generation LLC [Member]
Classification of net accumulated deferred income taxes
Change in valuation allowance on deferred tax asset			521
Edison International
Classification of net accumulated deferred income taxes
Tax benefits generated but not yet utilized by EIX under tax allocation agreement	1,435
Edison International | Capistrano Wind Holdings
Classification of net accumulated deferred income taxes
Tax benefits generated under tax allocation agreement	126
Edison International | Capistrano Wind, LLC
Classification of net accumulated deferred income taxes
Tax benefits generated and utilized by EIX under tax allocation agreement	27
Income Tax-Allocation Agreements [Member]
Classification of net accumulated deferred income taxes
Other long-term assets	31		18
Payables to affiliates	15		(33)
Other Liabilities, Noncurrent	$ 6		$ (21)

[1] During 2012, EME recorded a non-cash distribution to EIX related to the tax-allocation agreements. During 2013, EME received contributions from EIX related to the tax-allocation agreements. See Note 7—Income Taxes—EME—Deferred Tax Assets and Liabilities.

[2] During 2013, EME received a non-cash contribution from EIX related to the tax-allocation agreements. During 2012, EME recorded a non-cash distribution to EIX related to the tax-allocation agreements. See Note 7—Income Taxes—EME—Deferred Tax Assets and Liabilities.