Investments Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Estimated fair value asset	$ 2	$ 0
Estimated fair value liability	5	3
Not Designated as Hedging Instrument [Member] | Currency forwards [Member]
Derivative [Line Items]
Derivative, Notional Amount	18	9
Estimated fair value asset	2	0
Estimated fair value liability	0	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	184
Estimated fair value asset	0	0
Estimated fair value liability	$ 5	$ 3