Debt (Non-recourse Debt Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Construction line of credit facility remaining borrowing capacity	$ 2,300,000,000
Other line of credit remaining borrowing capacity	2,400,000,000
Restricted cash and debt service reserves	245,000,000	492,000,000
Restricted net assets	2,700,000,000
Increase (Decrease) in Interest Expense, Debt	(48,000,000)	(34,000,000)
Non-Recourse Debt | Mong Duong Subsidiary | Construction Loans
Debt Instrument [Line Items]
Debt face amount	364,000,000
Non-Recourse Debt | Angamos
Debt Instrument [Line Items]
Debt face amount	800,000,000
Repayments of long-term debt	780,000,000
Non-Recourse Debt | Gener Subsidiary
Debt Instrument [Line Items]
Debt face amount	700,000,000
Repayments of long-term debt	905,000,000
Non-Recourse Debt | US Generation Holdings
Debt Instrument [Line Items]
Debt face amount	299,000,000
Non-Recourse Debt | Electropaulo
Debt Instrument [Line Items]
Debt face amount	253,000,000
Repayments of long-term debt	110,000,000
Non-Recourse Debt | DPL Subsidiary
Debt Instrument [Line Items]
Debt face amount	200,000,000
Repayments of long-term debt	364,000,000
Non-Recourse Debt | Tiete Subsidiary
Debt Instrument [Line Items]
Debt face amount	318,000,000
Repayments of long-term debt	132,000,000
Non-Recourse Debt | Cochrane Subsidiary | Construction Loans
Debt Instrument [Line Items]
Debt face amount	305,000,000
Non-Recourse Debt | Sul Subsidiary
Debt Instrument [Line Items]
Debt face amount	185,000,000
Non-Recourse Debt | Southland
Debt Instrument [Line Items]
Repayments of long-term debt	188,000,000
Non-Recourse Debt | Chivor
Debt Instrument [Line Items]
Repayments of long-term debt	165,000,000
Non-Recourse Debt | UK Wind
Debt Instrument [Line Items]
Repayments of long-term debt	114,000,000
Non-Recourse Debt | Warrior Run | Construction Loans
Debt Instrument [Line Items]
Debt face amount	$ 109,000,000