Condensed Consolidating Financial Information - Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidating Financial Information
Revenue	$ 1,565	$ 1,586	$ 3,142	$ 3,172
Costs and Expenses:
Cost of Revenue	616	648	1,245	1,305
Depreciation and Amortization	199	191	393	378
Selling, General and Administrative	610	614	1,209	1,240
Total Costs and Expenses	1,425	1,453	2,847	2,923
Operating Income (Loss)	140	133	295	249
Other Income (Expense):
Interest income	0	1	0	2
Interest expense	(167)	(181)	(336)	(370)
Interest income (expense) affiliates, net	0	0	0	0
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Other, net	14	(7)	(36)	(59)
Total Other Expense	(153)	(187)	(372)	(427)
Income (Loss) Before Income Taxes	(13)	(54)	(77)	(178)
Income Tax Expense	(11)	(8)	(25)	(22)
Net Income (Loss)	(24)	(62)	(102)	(200)
Other Comprehensive Loss, Net of Income Taxes	(11)	(56)	(63)	(14)
Comprehensive Income (Loss)	(35)	(118)	(165)	(214)
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	0	0	1	1
Total Costs and Expenses	0	0	1	1
Operating Income (Loss)	0	0	(1)	(1)
Other Income (Expense):
Interest income		0		0
Interest expense	(37)	(38)	(76)	(80)
Interest income (expense) affiliates, net	272	245	545	490
Equity in net earnings (losses) of subsidiaries	(259)	(269)	(570)	(570)
Other, net	0	0	0	(39)
Total Other Expense	(24)	(62)	(101)	(199)
Income (Loss) Before Income Taxes	(24)	(62)	(102)	(200)
Income Tax Expense	0	0	0	0
Net Income (Loss)	(24)	(62)	(102)	(200)
Other Comprehensive Loss, Net of Income Taxes	(11)	(56)	(63)	(14)
Comprehensive Income (Loss)	(35)	(118)	(165)	(214)
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	0	0	0	0
Total Costs and Expenses	0	0	0	0
Operating Income (Loss)	0	0	0	0
Other Income (Expense):
Interest income		0		0
Interest expense	(125)	(134)	(251)	(273)
Interest income (expense) affiliates, net	425	403	855	802
Equity in net earnings (losses) of subsidiaries	(559)	(538)	(1,173)	(1,077)
Other, net	0	0	(1)	(22)
Total Other Expense	(259)	(269)	(570)	(570)
Income (Loss) Before Income Taxes	(259)	(269)	(570)	(570)
Income Tax Expense	0	0	0	0
Net Income (Loss)	(259)	(269)	(570)	(570)
Other Comprehensive Loss, Net of Income Taxes	(11)	(56)	(63)	(14)
Comprehensive Income (Loss)	(270)	(325)	(633)	(584)
Level 3 Communications, LLC
Condensed Consolidating Financial Information
Revenue	694	659	1,379	1,285
Costs and Expenses:
Cost of Revenue	256	244	517	480
Depreciation and Amortization	71	66	142	133
Selling, General and Administrative	412	396	793	797
Total Costs and Expenses	739	706	1,452	1,410
Operating Income (Loss)	(45)	(47)	(73)	(125)
Other Income (Expense):
Interest income		0		1
Interest expense	0	(1)	(1)	(1)
Interest income (expense) affiliates, net	(669)	(558)	(1,338)	(1,117)
Equity in net earnings (losses) of subsidiaries	130	25	276	61
Other, net	1	2	2	3
Total Other Expense	(538)	(532)	(1,061)	(1,053)
Income (Loss) Before Income Taxes	(583)	(579)	(1,134)	(1,178)
Income Tax Expense	0	(1)	(1)	(2)
Net Income (Loss)	(583)	(580)	(1,135)	(1,180)
Other Comprehensive Loss, Net of Income Taxes	0	0	0	0
Comprehensive Income (Loss)	(583)	(580)	(1,135)	(1,180)
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Revenue	928	991	1,884	2,014
Costs and Expenses:
Cost of Revenue	417	465	849	946
Depreciation and Amortization	128	125	251	245
Selling, General and Administrative	198	221	415	448
Total Costs and Expenses	743	811	1,515	1,639
Operating Income (Loss)	185	180	369	375
Other Income (Expense):
Interest income		1		1
Interest expense	(5)	(8)	(8)	(16)
Interest income (expense) affiliates, net	(28)	(90)	(62)	(175)
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Other, net	13	(9)	(37)	(1)
Total Other Expense	(20)	(106)	(107)	(191)
Income (Loss) Before Income Taxes	165	74	262	184
Income Tax Expense	(11)	(7)	(24)	(20)
Net Income (Loss)	154	67	238	164
Other Comprehensive Loss, Net of Income Taxes	(11)	(65)	(63)	(30)
Comprehensive Income (Loss)	143	2	175	134
Eliminations
Condensed Consolidating Financial Information
Revenue	(57)	(64)	(121)	(127)
Costs and Expenses:
Cost of Revenue	(57)	(61)	(121)	(121)
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative	0	(3)	0	(6)
Total Costs and Expenses	(57)	(64)	(121)	(127)
Operating Income (Loss)	0	0	0	0
Other Income (Expense):
Interest income		0		0
Interest expense	0	0	0	0
Interest income (expense) affiliates, net	0	0	0	0
Equity in net earnings (losses) of subsidiaries	688	782	1,467	1,586
Other, net	0	0	0	0
Total Other Expense	688	782	1,467	1,586
Income (Loss) Before Income Taxes	688	782	1,467	1,586
Income Tax Expense	0	0	0	0
Net Income (Loss)	688	782	1,467	1,586
Other Comprehensive Loss, Net of Income Taxes	22	121	126	44
Comprehensive Income (Loss)	$ 710	$ 903	$ 1,593	$ 1,630