Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended					1 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Interest Rate Swap	Dec. 31, 2012 Interest Rate Swap	Mar. 31, 2007 Parent Company [Member]	Dec. 31, 2013 Parent Company [Member]	Mar. 31, 2007 Parent Company [Member] Interest Rate Swap, Agreement One	Mar. 31, 2007 Parent Company [Member] Interest Rate Swap, Agreement Two	Dec. 31, 2013 Interest Expense	Dec. 31, 2012 Interest Expense	Dec. 31, 2013 Other Current Liabilities [Member]	Dec. 31, 2012 Other Noncurrent Liabilities
Derivative
Interest rate swaps, number of instruments						2	2
Interest rate swaps, notional amount						$ 1,000	$ 1,000	$ 500	$ 500
Basis of interest payment						three month LIBOR	three month LIBOR	three month LIBOR	three month LIBOR
Fixed interest rate paid under agreement (as a percent)								4.93%	4.92%
Loss on Cash Flow Hedge Ineffectiveness					(60)
Interest rate swap agreements - Other noncurrent liabilities												12	56
Cash flow hedging contracts, gains (losses) recognized in Other Comprehensive Income (Loss)	0	90	18
Cash flow hedging contracts, amount of gains (losses) reclassified from AOCI to Interest Expense										0	26
Gain (Loss) on interest rate swap agreements not designated as hedging instruments	$ (2)	$ (64)	$ 0	$ (2)	$ (4)