Derivative Financial Instruments (Summary of aggregate contractual or notional amounts and gross estimated fair values related to derivative financial instruments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Estimated fair value asset	$ 0
Estimated fair value (liability)	(3)
Not Designated as Hedging Instrument [Member] | Currency forwards [Member]
Derivative [Line Items]
Derivative, Notional Amount	9
Estimated fair value asset	0
Estimated fair value (liability)	0
Not Designated as Hedging Instrument [Member] | Equity warrants [Member]
Derivative [Line Items]
Derivative, Notional Amount	5	5
Estimated fair value asset	0	0
Estimated fair value (liability)	0	0
Not Designated as Hedging Instrument [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Derivative, Notional Amount	184
Estimated fair value asset	0
Estimated fair value (liability)	$ (3)