Risk Management (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivative [Line Items]
Notional amount of foreign currency derivatives	$ 523,000,000	$ 524,000,000
Maximum term of derivative instruments that hedge forecasted transactions	7 months
Weighted average duration of derivative instruments that hedge forecasted transactions	3 months
Fair value of derivative liabilities	7,000,000	8,000,000
Aggregate credit risk with all counterparties	3,000,000
Interest Rate Contracts
Derivative [Line Items]
Principal amount outstanding	1,900,000,000
Interest Rate Contracts | Other Liabilities
Derivative [Line Items]
Weighted average fixed rate payment on the Interest Agreement	4.92%
Not Designated As Hedging Instruments
Derivative [Line Items]
Fair value of derivative liabilities	7,000,000	6,000,000
Not Designated As Hedging Instruments | Interest Rate Contracts | Other Liabilities
Derivative [Line Items]
Fair value of derivative liabilities	$ 4,000,000	$ 3,000,000