Business Acquisitions and Dispositions Business Acquisitions and Dispositions - EME 1 (Details 5) $ in Millions		3 Months Ended
	Apr. 02, 2014 USD ($) MW shares	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014	Apr. 30, 2014 MW
Business Acquisition [Line Items]
Goodwill				$ 662	$ 999
EME [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt						$ 1,249
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		$ 1,422				1,422
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Cash		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current and Non-Current Assets						724
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Assets		72
Business Acquisition, Purchase Price Allocation, Other Assets, Adjusted		796
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment						2,438
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment		(3)
Business Acquisition, Purchase Price Allocation, Property, Plant and Equipment, Adjusted		2,435
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles						172
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles		0
Business Acquisition, Purchase Price Allocation, Intangible Assets, Other than Goodwill, Adjusted		172
Goodwill						334
Goodwill, Purchase Accounting Adjustments		(56)
Goodwill, Adjusted		278
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets						773
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Noncurrent Assets		0
Business Acquisition, Purchase Price Allocation, Noncurrent Assets, Adjusted		773
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets						5,863
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Total Assets		13
Business Acquisition, Purchase Price Allocation, Assets Acquired, Adjusted		5,876
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current and Non-Current Liabilities						629
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Current and Noncurrent Liabilities		13
Business Acquisition, Purchase Price Allocation, Current and Non-current Liabilities, Adjusted		642
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Out-of-market Contracts and Leases						159
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Out of Market Contracts and Leases		0
Business Acquisition, Purchase Price Allocation, Out of Market Contracts and Leases, Adjusted		159
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Noncurrent Liabilities Longterm Debt		0
Business Acquisition, Purchase Price Allocation, Noncurrent Liabilities, Long-term Debt, Adjusted		1,249
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities						2,037
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities		13
Business Acquisition, Purchase Price Allocation, Liabilities Assumed, Adjusted		2,050
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value						352
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Noncontrolling Interest		0
Business Acquisition, Purchase Price Allocation, Noncontrolling Interest, Adjusted		352
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net						$ 3,474
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Net Assets Acquired		0
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net Adjusted		$ 3,474
Edison Mission Energy [Member]
Business Acquisition [Line Items]
Power Generation Capacity, Megawatts | MW	8,000
Business Combination, Consideration Transferred	$ 3,500
Business Combination, Estimated Consideration Transferred, Estimated Liabilities Incurred	700
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	$ 1,200
Mission Del Sol [Member]
Business Acquisition [Line Items]
Percentage of Ownership							100.00%
Sunrise Facility [Member]
Business Acquisition [Line Items]
Power Generation Capacity, Megawatts | MW								586
Common Stock [Member] | Edison Mission Energy [Member]
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	12,671,977
Through 2034 [Member]
Business Acquisition [Line Items]
Repayments of Long-term Capital Lease Obligations			$ 405
EME [Member]
Business Acquisition [Line Items]
Goodwill				$ 276
Cogeneration facilities [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage								50.00%
Mission Del Sol [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage								50.00%