Commitments (Long-Term Purchase Commitments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Electricity Purchase Contracts
Long-Term Purchase Commitment [Line Items]
Purchases Under Long Term Contracts	$ 2,665	$ 2,819	$ 2,463
Future Commitments 2014	2,793
Future Commitments 2015	2,792
Future Commitments 2016	2,808
Future Commitments 2017	2,403
Future Commitments 2018	2,538
Future Commitments Thereafter	27,831
Future Commitments Total	41,165
Fuel Purchase Contracts
Long-Term Purchase Commitment [Line Items]
Purchases Under Long Term Contracts	1,590	1,832	1,577
Future Commitments 2014	1,274
Future Commitments 2015	718
Future Commitments 2016	437
Future Commitments 2017	432
Future Commitments 2018	434
Future Commitments Thereafter	3,451
Future Commitments Total	6,746
Other Purchase Contracts
Long-Term Purchase Commitment [Line Items]
Purchases Under Long Term Contracts	1,743	1,637	1,515
Future Commitments 2014	1,526
Future Commitments 2015	1,326
Future Commitments 2016	975
Future Commitments 2017	674
Future Commitments 2018	576
Future Commitments Thereafter	5,419
Future Commitments Total	$ 10,496