Acquisitions (Details) (USD $)	3 Months Ended
	Jun. 30, 2011	Apr. 20, 2011 mw customers
Business Acquisition [Line Items]
Amount paid	$ 3,500,000,000
Senior Unsecured Note 7375 Due 2021 And Senior Secured Term Loan LIBOR Plus 325 [Member] | DPL Acquisition [Member]
Business Acquisition [Line Items]
Recourse Debt Total	2,050,000,000
DPL Acquisition [Member]
Business Acquisition [Line Items]
Total enterprise value of DPL acquisition		4,700,000,000
Amount paid		3,500,000,000
Net debt portion of enterprise value of DPL acquisition		1,200,000,000
Customers Served		500,000
Generation Capacity Mega Watts		3,800
Business Acquisition Bridge Loan Committed	1,250,000,000	3,300,000,000
Business Acquisition Bridge Loan Committed Reduction	2,050,000,000
Business Acquisition Penalty Receivable From Acquiree For Early Rejection Of Merger Offer		$ 106,000,000