Derivatives (Additional Cash Collateral The Utility Would Be Required To Post If Its Credit Risk-Related Contingency Features Were Triggered) (Details) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Derivatives in a liability position with credit risk-related contingencies that are not fully collateralized		$ (9)	$ (2)
Collateral posting in the normal course of business related to these derivatives		7	0
Net position of derivative contracts/additional collateral posting requirements	[1]	$ (2)	$ (2)

[1] This calculation excludes the impact of closed but unpaid positions, as their settlement is not impacted by any of the Utility’s credit risk-related contingencies.