Condensed Consolidating Financial Information - Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Current Assets:
Cash and cash equivalents	$ 918	$ 616	$ 836	$ 768
Restricted cash and securities	10	2
Receivables, less allowances for doubtful accounts	648	259
Due from (to) affiliates	0	0
Other	131	83
Current assets of discontinued operations	0	12
Total Current Assets	1,707	972
Property, Plant and Equipment, net	8,136	5,285
Restricted Cash and Securities	51	49
Goodwill and Other Intangibles Assets, net	2,899	1,798
Investment in Subsidiaries	0	0
Other Assets, net	395	161
NonCurrent assets of discontinued operations	0	90
Total Assets	13,188	8,355
Current Liabilities:
Accounts payable	747	326
Current portion of long-term debt	65	180
Accrued payroll and employee benefits	209	84
Accrued interest	216	146
Current portion of deferred revenue	264	151
Other	157	53
Current liabilities of discontinued operations	0	16
Total Current Liabilities	1,658	956
Long-Term Debt, less current portion	8,385	6,268
Deferred Revenue, less current portion	885	736
Other Liabilities	1,067	440
NonCurrent Liabilities of Discontinued Operations	0	112
Commitments and Contingencies	0	0
Stockholders' Equity (Deficit)	1,193	(157)	491	1,021
Total Liabilities and Stockholders' Equity (Deficit)	13,188	8,355
Level 3 Communications, Inc.
Current Assets:
Cash and cash equivalents	2	173	236	67
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from (to) affiliates	13,472	11,927
Other	3	4
Current assets of discontinued operations		0
Total Current Assets	13,477	12,104
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	18	18
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	(10,718)	(10,437)
Other Assets, net	13	9
NonCurrent assets of discontinued operations		0
Total Assets	2,790	1,694
Current Liabilities:
Accounts payable	0	1
Current portion of long-term debt	0	176
Accrued payroll and employee benefits	0	0
Accrued interest	50	47
Current portion of deferred revenue	0	0
Other	0	0
Current liabilities of discontinued operations		0
Total Current Liabilities	50	224
Long-Term Debt, less current portion	1,533	1,612
Deferred Revenue, less current portion	0	0
Other Liabilities	14	15
NonCurrent Liabilities of Discontinued Operations		0
Stockholders' Equity (Deficit)	1,193	(157)
Total Liabilities and Stockholders' Equity (Deficit)	2,790	1,694
Level 3 Financing, Inc.
Current Assets:
Cash and cash equivalents	6	7	8	10
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from (to) affiliates	14,584	11,424
Other	16	10
Current assets of discontinued operations		0
Total Current Assets	14,606	11,441
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	0	0
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	(18,467)	(17,176)
Other Assets, net	109	65
NonCurrent assets of discontinued operations		0
Total Assets	(3,752)	(5,670)
Current Liabilities:
Accounts payable	0	0
Current portion of long-term debt	0	0
Accrued payroll and employee benefits	0	0
Accrued interest	165	99
Current portion of deferred revenue	0	0
Other	1	1
Current liabilities of discontinued operations		0
Total Current Liabilities	166	100
Long-Term Debt, less current portion	6,688	4,564
Deferred Revenue, less current portion	0	0
Other Liabilities	116	107
NonCurrent Liabilities of Discontinued Operations		0
Stockholders' Equity (Deficit)	(10,722)	(10,441)
Total Liabilities and Stockholders' Equity (Deficit)	(3,752)	(5,670)
Level 3 Communications, LLC
Current Assets:
Cash and cash equivalents	618	350	431	555
Restricted cash and securities	1	1
Receivables, less allowances for doubtful accounts	59	46
Due from (to) affiliates	(28,092)	(26,113)
Other	48	41
Current assets of discontinued operations		0
Total Current Assets	(27,366)	(25,675)
Property, Plant and Equipment, net	2,823	2,937
Restricted Cash and Securities	19	21
Goodwill and Other Intangibles Assets, net	481	543
Investment in Subsidiaries	3,412	3,575
Other Assets, net	6	6
NonCurrent assets of discontinued operations		0
Total Assets	(20,625)	(18,593)
Current Liabilities:
Accounts payable	37	57
Current portion of long-term debt	2	2
Accrued payroll and employee benefits	116	78
Accrued interest	0	0
Current portion of deferred revenue	107	115
Other	52	45
Current liabilities of discontinued operations		0
Total Current Liabilities	314	297
Long-Term Debt, less current portion	22	24
Deferred Revenue, less current portion	612	673
Other Liabilities	146	154
NonCurrent Liabilities of Discontinued Operations		0
Stockholders' Equity (Deficit)	(21,719)	(19,741)
Total Liabilities and Stockholders' Equity (Deficit)	(20,625)	(18,593)
Other Non-Guarantor Subsidiaries
Current Assets:
Cash and cash equivalents	292	86	161	136
Restricted cash and securities	9	1
Receivables, less allowances for doubtful accounts	589	213
Due from (to) affiliates	36	2,762
Other	64	28
Current assets of discontinued operations		12
Total Current Assets	990	3,102
Property, Plant and Equipment, net	5,313	2,348
Restricted Cash and Securities	14	10
Goodwill and Other Intangibles Assets, net	2,418	1,255
Investment in Subsidiaries	0	0
Other Assets, net	267	81
NonCurrent assets of discontinued operations		90
Total Assets	9,002	6,886
Current Liabilities:
Accounts payable	710	268
Current portion of long-term debt	63	2
Accrued payroll and employee benefits	93	6
Accrued interest	1	0
Current portion of deferred revenue	157	36
Other	104	7
Current liabilities of discontinued operations		16
Total Current Liabilities	1,128	335
Long-Term Debt, less current portion	142	68
Deferred Revenue, less current portion	273	63
Other Liabilities	791	164
NonCurrent Liabilities of Discontinued Operations		112
Stockholders' Equity (Deficit)	6,668	6,144
Total Liabilities and Stockholders' Equity (Deficit)	9,002	6,886
Eliminations
Current Assets:
Cash and cash equivalents	0	0	0	0
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from (to) affiliates	0	0
Other	0	0
Current assets of discontinued operations		0
Total Current Assets	0	0
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	0	0
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	25,773	24,038
Other Assets, net	0	0
NonCurrent assets of discontinued operations		0
Total Assets	25,773	24,038
Current Liabilities:
Accounts payable	0	0
Current portion of long-term debt	0	0
Accrued payroll and employee benefits	0	0
Accrued interest	0	0
Current portion of deferred revenue	0	0
Other	0	0
Current liabilities of discontinued operations		0
Total Current Liabilities	0	0
Long-Term Debt, less current portion	0	0
Deferred Revenue, less current portion	0	0
Other Liabilities	0	0
NonCurrent Liabilities of Discontinued Operations		0
Stockholders' Equity (Deficit)	25,773	24,038
Total Liabilities and Stockholders' Equity (Deficit)	$ 25,773	$ 24,038