Condensed Consolidating Financial Information - Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Condensed Consolidating Financial Information
Revenue	$ 1,629	$ 1,569	$ 4,863	$ 4,711
Costs and Expenses:
Cost of Revenue	607	608	1,834	1,853
Network Related Expenses	307	314	901	916
Depreciation and Amortization	187	203	558	596
Selling, General and Administrative Expenses	266	292	788	899
Total Costs and Expenses	1,367	1,417	4,081	4,264
Operating Income (Loss)	262	152	782	447
Interest Income, Other	1	0	1	0
Other Income (Expense):
Interest expense	(159)	(165)	(459)	(501)
Interest income (expense) affiliates, net	0	0	0	0
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Other, net	(11)	6	(49)	(30)
Total Other Expense	(169)	(159)	(507)	(531)
Income (Loss) before Income Taxes	93	(7)	275	(84)
Income Tax Expense	(8)	(14)	(27)	(39)
Net Income (Loss)	85	(21)	248	(123)
Other Comprehensive Income (Loss), Net of Income Taxes	(137)	42	(118)	(21)
Comprehensive Income (Loss)	(52)	21	130	(144)
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Revenue	0	0	0	0
Costs and Expenses:
Cost of Revenue	0		0	0
Network Related Expenses	0	0	0	0
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative Expenses	6	1	7	2
Total Costs and Expenses	6	1	7	2
Operating Income (Loss)	(6)	(1)	(7)	(2)
Interest Income, Other	0		0
Other Income (Expense):
Interest expense	(34)	(38)	(102)	(114)
Interest income (expense) affiliates, net	314	274	905	819
Equity in net earnings (losses) of subsidiaries	(189)	(255)	(548)	(825)
Other, net	0	0	0	0
Total Other Expense	91	(19)	255	(120)
Income (Loss) before Income Taxes	85	(20)	248	(122)
Income Tax Expense	0	(1)	0	(1)
Net Income (Loss)	85	(21)	248	(123)
Other Comprehensive Income (Loss), Net of Income Taxes	(137)	42	(118)	(21)
Comprehensive Income (Loss)	(52)	21	130	(144)
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Revenue	0	0	0	0
Costs and Expenses:
Cost of Revenue	0		0	0
Network Related Expenses	0	0	0	0
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative Expenses	0	1	1	1
Total Costs and Expenses	0	1	1	1
Operating Income (Loss)	0	(1)	(1)	(1)
Interest Income, Other	0		0
Other Income (Expense):
Interest expense	(112)	(123)	(337)	(374)
Interest income (expense) affiliates, net	452	429	1,370	1,284
Equity in net earnings (losses) of subsidiaries	(528)	(542)	(1,577)	(1,715)
Other, net	0	(18)	0	(19)
Total Other Expense	(188)	(254)	(544)	(824)
Income (Loss) before Income Taxes	(188)	(255)	(545)	(825)
Income Tax Expense	(1)	0	(3)	0
Net Income (Loss)	(189)	(255)	(548)	(825)
Other Comprehensive Income (Loss), Net of Income Taxes	0	42	0	(21)
Comprehensive Income (Loss)	(189)	(213)	(548)	(846)
Level 3 Communications, LLC
Condensed Consolidating Financial Information
Revenue	781	711	2,278	2,090
Costs and Expenses:
Cost of Revenue	291	264	869	781
Network Related Expenses	195	194	567	572
Depreciation and Amortization	70	73	209	215
Selling, General and Administrative Expenses	181	191	505	606
Total Costs and Expenses	737	722	2,150	2,174
Operating Income (Loss)	44	(11)	128	(84)
Interest Income, Other	0		0
Other Income (Expense):
Interest expense	(1)	(1)	(1)	(2)
Interest income (expense) affiliates, net	(730)	(670)	(2,169)	(2,008)
Equity in net earnings (losses) of subsidiaries	162	122	502	398
Other, net	2	1	6	3
Total Other Expense	(567)	(548)	(1,662)	(1,609)
Income (Loss) before Income Taxes	(523)	(559)	(1,534)	(1,693)
Income Tax Expense	0	(1)	(1)	(2)
Net Income (Loss)	(523)	(560)	(1,535)	(1,695)
Other Comprehensive Income (Loss), Net of Income Taxes	0	0	0	0
Comprehensive Income (Loss)	(523)	(560)	(1,535)	(1,695)
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Revenue	901	919	2,750	2,803
Costs and Expenses:
Cost of Revenue	369	405	1,130	1,254
Network Related Expenses	112	120	334	344
Depreciation and Amortization	117	130	349	381
Selling, General and Administrative Expenses	79	99	275	290
Total Costs and Expenses	677	754	2,088	2,269
Operating Income (Loss)	224	165	662	534
Interest Income, Other	1		1
Other Income (Expense):
Interest expense	(12)	(3)	(19)	(11)
Interest income (expense) affiliates, net	(36)	(33)	(106)	(95)
Equity in net earnings (losses) of subsidiaries	0	0	0	0
Other, net	(13)	23	(55)	(14)
Total Other Expense	(60)	(13)	(179)	(120)
Income (Loss) before Income Taxes	164	152	483	414
Income Tax Expense	(7)	(12)	(23)	(36)
Net Income (Loss)	157	140	460	378
Other Comprehensive Income (Loss), Net of Income Taxes	(137)	42	(118)	(21)
Comprehensive Income (Loss)	20	182	342	357
Eliminations
Condensed Consolidating Financial Information
Revenue	(53)	(61)	(165)	(182)
Costs and Expenses:
Cost of Revenue	(53)	(61)	(165)	(182)
Network Related Expenses	0	0	0	0
Depreciation and Amortization	0	0	0	0
Selling, General and Administrative Expenses	0	0	0	0
Total Costs and Expenses	(53)	(61)	(165)	(182)
Operating Income (Loss)	0	0	0	0
Interest Income, Other	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	555	675	1,623	2,142
Other, net	0	0	0	0
Total Other Expense	555	675	1,623	2,142
Income (Loss) before Income Taxes	555	675	1,623	2,142
Income Tax Expense	0	0	0	0
Net Income (Loss)	555	675	1,623	2,142
Other Comprehensive Income (Loss), Net of Income Taxes	137	(84)	118	42
Comprehensive Income (Loss)	$ 692	$ 591	$ 1,741	$ 2,184