Condensed Consolidating Financial Information - Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Condensed Consolidating Financial Information
Revenue	$ 1,625	$ 1,565	$ 3,234	$ 3,142
Costs and Expenses:
Cost of Revenue	613	616	1,227	1,245
Depreciation and Amortization	187	199	371	393
Selling, General and Administrative	569	610	1,116	1,209
Total Costs and Expenses	1,369	1,425	2,714	2,847
Operating Income (Loss)	256	140	520	295
Other Income (Expense):
Interest expense	(149)	(167)	(300)	(336)
Interest income (expense) affiliates, net	0	0	0	0
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Other, net	(44)	14	(38)	(36)
Total Other Expense	(193)	(153)	(338)	(372)
Income (Loss) before Income Taxes	63	(13)	182	(77)
Income Tax Expense	(12)	(11)	(19)	(25)
Net Income (Loss)	51	(24)	163	(102)
Other Comprehensive Income (Loss), Net of Income Taxes	13	(11)	19	(63)
Comprehensive Income (Loss)	64	(35)	182	(165)
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Revenue	0	0	0	0
Costs and Expenses:
Cost of Revenue	0	0	0	0
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative	1	0	1	1
Total Costs and Expenses	1	0	1	1
Operating Income (Loss)	(1)	0	(1)	(1)
Other Income (Expense):
Interest expense	(34)	(37)	(68)	(76)
Interest income (expense) affiliates, net	303	272	591	545
Equity in net earnings (losses) of subsidiaries	(217)	(259)	(359)	(570)
Other, net	0	0	0	0
Total Other Expense	52	(24)	164	(101)
Income (Loss) before Income Taxes	51	(24)	163	(102)
Income Tax Expense	0	0	0	0
Net Income (Loss)	51	(24)	163	(102)
Other Comprehensive Income (Loss), Net of Income Taxes	13	(11)	19	(63)
Comprehensive Income (Loss)	64	(35)	182	(165)
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Revenue	0	0	0	0
Costs and Expenses:
Cost of Revenue	0	0	0	0
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative	1	0	1	0
Total Costs and Expenses	1	0	1	0
Operating Income (Loss)	(1)	0	(1)	0
Other Income (Expense):
Interest expense	(113)	(125)	(225)	(251)
Interest income (expense) affiliates, net	459	425	918	855
Equity in net earnings (losses) of subsidiaries	(561)	(559)	(1,049)	(1,173)
Other, net	0	0	0	(1)
Total Other Expense	(215)	(259)	(356)	(570)
Income (Loss) before Income Taxes	(216)	(259)	(357)	(570)
Income Tax Expense	(1)	0	(2)	0
Net Income (Loss)	(217)	(259)	(359)	(570)
Other Comprehensive Income (Loss), Net of Income Taxes	0	(11)	0	(63)
Comprehensive Income (Loss)	(217)	(270)	(359)	(633)
Level 3 Communications, LLC
Condensed Consolidating Financial Information
Revenue	760	694	1,497	1,379
Costs and Expenses:
Cost of Revenue	288	256	578	517
Depreciation and Amortization	69	71	139	142
Selling, General and Administrative	371	412	696	793
Total Costs and Expenses	728	739	1,413	1,452
Operating Income (Loss)	32	(45)	84	(73)
Other Income (Expense):
Interest expense	1	0	0	(1)
Interest income (expense) affiliates, net	(727)	(669)	(1,439)	(1,338)
Equity in net earnings (losses) of subsidiaries	162	130	340	276
Other, net	1	1	4	2
Total Other Expense	(563)	(538)	(1,095)	(1,061)
Income (Loss) before Income Taxes	(531)	(583)	(1,011)	(1,134)
Income Tax Expense	0	0	(1)	(1)
Net Income (Loss)	(531)	(583)	(1,012)	(1,135)
Other Comprehensive Income (Loss), Net of Income Taxes	0	0	0	0
Comprehensive Income (Loss)	(531)	(583)	(1,012)	(1,135)
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Revenue	918	928	1,849	1,884
Costs and Expenses:
Cost of Revenue	378	417	761	849
Depreciation and Amortization	118	128	232	251
Selling, General and Administrative	196	198	418	415
Total Costs and Expenses	692	743	1,411	1,515
Operating Income (Loss)	226	185	438	369
Other Income (Expense):
Interest expense	(3)	(5)	(7)	(8)
Interest income (expense) affiliates, net	(35)	(28)	(70)	(62)
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Other, net	(45)	13	(42)	(37)
Total Other Expense	(83)	(20)	(119)	(107)
Income (Loss) before Income Taxes	143	165	319	262
Income Tax Expense	(11)	(11)	(16)	(24)
Net Income (Loss)	132	154	303	238
Other Comprehensive Income (Loss), Net of Income Taxes	13	(11)	19	(63)
Comprehensive Income (Loss)	145	143	322	175
Eliminations
Condensed Consolidating Financial Information
Revenue	(53)	(57)	(112)	(121)
Costs and Expenses:
Cost of Revenue	(53)	(57)	(112)	(121)
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative	0	0	0	0
Total Costs and Expenses	(53)	(57)	(112)	(121)
Operating Income (Loss)	0	0	0	0
Other Income (Expense):
Interest expense	0	0	0	0
Interest income (expense) affiliates, net	0	0	0	0
Equity in net earnings (losses) of subsidiaries	616	688	1,068	1,467
Other, net	0	0	0	0
Total Other Expense	616	688	1,068	1,467
Income (Loss) before Income Taxes	616	688	1,068	1,467
Income Tax Expense	0	0	0	0
Net Income (Loss)	616	688	1,068	1,467
Other Comprehensive Income (Loss), Net of Income Taxes	(13)	22	(19)	126
Comprehensive Income (Loss)	$ 603	$ 710	$ 1,049	$ 1,593