Derivatives (Gains And Losses On Derivative Instruments) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Unrealized gain (loss) - regulatory assets and liabilities	[1]	$ (45)	$ (6)	$ (69)	$ 79
Realized gain (loss) - cost of electricity	[2]	1	(22)	4	(48)
Realized loss - cost of natural gas	[2]	(3)	(4)	(8)	(7)
Net commodity risk		$ (47)	$ (32)	$ (73)	$ 24

[1] Unrealized gains and losses on commodity risk-related derivative instruments are recorded to regulatory liabilities or assets, respectively, rather than being recorded to the Condensed Consolidated Statements of Income. These amounts exclude the impact of cash collateral postings.

[2] These amounts are fully passed through to customers in rates. Accordingly, net income was not impacted by realized amounts on these instruments.