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Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended			3 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2015	Dec. 31, 2011	Dec. 31, 2010	Mar. 04, 2011	Jan. 29, 2015
Subsequent Events
Cash and cash equivalents	$ 580				$ 631				$ 580	$ 631	$ 979		$ 918	$ 918
Other, net	(20)us-gaap_OtherNonoperatingIncomeExpense	(11)us-gaap_OtherNonoperatingIncomeExpense	(44)us-gaap_OtherNonoperatingIncomeExpense	6us-gaap_OtherNonoperatingIncomeExpense	9us-gaap_OtherNonoperatingIncomeExpense	23us-gaap_OtherNonoperatingIncomeExpense	14us-gaap_OtherNonoperatingIncomeExpense	(50)us-gaap_OtherNonoperatingIncomeExpense	(69)us-gaap_OtherNonoperatingIncomeExpense	(4)us-gaap_OtherNonoperatingIncomeExpense	(58)us-gaap_OtherNonoperatingIncomeExpense
Loss on modification and extinguishment of debt, net	(53)	0	0	0	(67)	(17)	0	0	(53)	(84)	(160)
Convertible Senior Notes due 2013 (15.0%)
Subsequent Events
Debt instrument, stated interest rate (as a percent)	15.00%								15.00%				15.00%
Senior Notes due 2019 (9.375%)
Subsequent Events
Debt instrument, stated interest rate (as a percent)	9.375%								9.375%				9.375%
Level 3 Financing [Member] \| Senior Notes due 2019 (9.375%)
Subsequent Events
Debt Instrument, Face Amount															500.0
Debt instrument, stated interest rate (as a percent)	9.375%								9.375%
Level 3 Financing [Member] \| Subsequent Event [Member] \| Senior Notes 5point 625Percent Due 2023 [Member]
Subsequent Events
Debt Instrument, Face Amount																500.0
Debt instrument, stated interest rate (as a percent)																5.625%
Level 3 Financing [Member] \| Subsequent Event [Member] \| Senior Notes due 2019 (9.375%)
Subsequent Events
Debt Instrument, Face Amount																500.0
Debt instrument, stated interest rate (as a percent)																9.375%
Loss on modification and extinguishment of debt, net												40
Level 3 Communications, Inc.
Subsequent Events
Cash and cash equivalents	$ 7				$ 8				$ 7	$ 8	$ 253			$ 2