Debt and Credit Agreements (Credit Facilities and Letters of Credit) (Details) (Letter of Credit, USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]
Line of credit facility	$ 292
Standby letters of credit	163
Restricted deposits	22	49
Standby letters of credit expiring in 2013	59
Standby Letters of Credit Expiring within Four Years	17
Standby letters of credit expiring in 2017	9
Standby Letters of Credit Expiring within Seven Years	27
Standby Letters of Credit Expiring within Eight Years	18
Standby letters of credit expiring in 2021	13
Standby letters of credit expiring in 2022	20
Walnut Creek
Line of Credit Facility [Line Items]
Standby letters of credit	22
Other EME Subsidiaries
Line of Credit Facility [Line Items]
Line of credit facility	101
Edison Mission Wind [Member]
Line of Credit Facility [Line Items]
Line of credit facility	75
Mountain Wind Power I Project
Line of Credit Facility [Line Items]
Line of credit facility	10
Mountain Wind Power II Project
Line of Credit Facility [Line Items]
Line of credit facility	$ 16