Risk Management (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Notional amount of foreign currency derivatives	$ 628	$ 837
Fair value of derivative liabilities		5
Credit Concentration Risk
Derivative [Line Items]
Notional amount of foreign currency derivatives	1
Interest rate contracts | Other Liabilities
Derivative [Line Items]
Weighted average fixed rate payment on the Interest Agreement	4.02%
Not Designated As Hedging Instruments
Derivative [Line Items]
Fair value of derivative liabilities	7	4
Not Designated As Hedging Instruments | Interest rate contracts | Other Liabilities
Derivative [Line Items]
Fair value of derivative liabilities	$ 2	$ 3