Derivative Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Interest Rate Swap	Sep. 30, 2012 Interest Rate Swap	Mar. 31, 2007 Level 3 Financing Inc. derivatives	Dec. 31, 2012 Level 3 Financing Inc. derivatives	Mar. 31, 2007 Level 3 Financing Inc. Interest Rate Swap, Agreement One	Mar. 31, 2007 Level 3 Financing Inc. Interest Rate Swap, Agreement Two	Dec. 31, 2012 Interest Expense	Dec. 31, 2011 Interest Expense	Dec. 31, 2012 Other Noncurrent Liabilities	Dec. 31, 2011 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%
Cash flow hedging contracts - Other noncurrent liabilities												0	90
Interest rate swap agreements - Other noncurrent liabilities												56	0
Cash flow hedging contracts, gains (losses) recognized in Other Comprehensive Income (Loss)	90	18	(16)
Cash flow hedging contracts, amount of gains (losses) reclassified from AOCI to Interest Expense										26	46
Embedded equity conversion rights located in Other Income (Expense) - Other, net	0	0	10
Gain (Loss) on interest rate swap agreements not designated as hedging instruments	$ (64)	$ 0	$ 0	$ (4)	$ (60)