Derivatives - Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
After-tax Derivative Activity recorded in AOCI
Unrealized losses (gains) on derivatives	$ 1	$ 2	$ (13)	$ 2
Reclassification to income of realized loss on derivatives			$ 7

Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax 1

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration