Accounting for Derivative Instruments and Hedging Activities Derivative instruments effect on the Company's condensed consolidated balance sheets (Details) (Interest Rate Swap [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Other long-term liabilities [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of interest rate derivatives not designated as hedges	$ 29	$ 0
Other long-term liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of interest rate derivatives designated as hedges	0	67
Accrued interest [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of interest rate derivatives not designated as hedges	10	0
Accrued interest [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of interest rate derivatives designated as hedges	0	8
Accumulated other comprehensive loss [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of interest rate derivatives not designated as hedges	(56)	0
Accumulated other comprehensive loss [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of interest rate derivatives designated as hedges	$ 0	$ (75)