Condensed Consolidating Financial Information - Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current Assets:
Cash and cash equivalents	$ 631	$ 979	$ 918	$ 616
Restricted cash and securities	7	8
Receivables, less allowances for doubtful accounts	673	714
Due from affiliates	0	0
Other	143	141
Total Current Assets	1,454	1,842
Property, Plant and Equipment, net	8,240	8,199
Restricted Cash and Securities	23	35
Goodwill and Other Intangibles Assets, net	2,782	2,833
Investment in Subsidiaries	0	0
Other Assets, net	375	398
Total Assets	12,874	13,307
Current Liabilities:
Accounts payable	625	779
Current portion of long-term debt	31	216
Accrued payroll and employee benefits	209	211
Accrued interest	160	209
Current portion of deferred revenue	253	251
Due to affiliates	0	0
Other	168	136
Total Current Liabilities	1,446	1,802
Long-Term Debt, less current portion	8,331	8,516
Deferred Revenue, less current portion	906	887
Other Liabilities	780	931
Commitments and Contingencies	0	0
Stockholders' Equity (Deficit)	1,411	1,171	1,193	(157)
Total Liabilities and Stockholders’ Equity	12,874	13,307
Level 3 Communications, Inc.
Current Assets:
Cash and cash equivalents	8	253	2	173
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from affiliates	15,507	14,446
Other	2	3
Total Current Assets	15,517	14,702
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	3	12
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	10,039	(11,756)
Other Assets, net	10	16
Total Assets	25,569	2,974
Current Liabilities:
Accounts payable	0	1
Current portion of long-term debt	0	172
Accrued payroll and employee benefits	0	0
Accrued interest	30	45
Current portion of deferred revenue	0	0
Due to affiliates	0	0
Other	0	1
Total Current Liabilities	30	219
Long-Term Debt, less current portion	1,370	1,570
Deferred Revenue, less current portion	0	0
Other Liabilities	15	14
Stockholders' Equity (Deficit)	24,154	1,171
Total Liabilities and Stockholders’ Equity	25,569	2,974
Level 3 Financing, Inc.
Current Assets:
Cash and cash equivalents	6	5	6	7
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from affiliates	16,886	15,709
Other	15	16
Total Current Assets	16,907	15,730
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	0	0
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	27,014	(20,470)
Other Assets, net	113	119
Total Assets	44,034	(4,621)
Current Liabilities:
Accounts payable	2	2
Current portion of long-term debt	0	6
Accrued payroll and employee benefits	0	0
Accrued interest	129	163
Current portion of deferred revenue	0	0
Due to affiliates	0	0
Other	13	1
Total Current Liabilities	144	172
Long-Term Debt, less current portion	6,905	6,886
Deferred Revenue, less current portion	0	0
Other Liabilities	27	81
Stockholders' Equity (Deficit)	36,958	(11,760)
Total Liabilities and Stockholders’ Equity	44,034	(4,621)
Level 3 Communications, LLC
Current Assets:
Cash and cash equivalents	347	386	618	350
Restricted cash and securities	1	1
Receivables, less allowances for doubtful accounts	79	93
Due from affiliates	0	0
Other	47	49
Total Current Assets	474	529
Property, Plant and Equipment, net	3,028	2,926
Restricted Cash and Securities	18	17
Goodwill and Other Intangibles Assets, net	395	429
Investment in Subsidiaries	3,735	3,242
Other Assets, net	11	11
Total Assets	7,661	7,154
Current Liabilities:
Accounts payable	42	53
Current portion of long-term debt	3	6
Accrued payroll and employee benefits	171	161
Accrued interest	0	0
Current portion of deferred revenue	131	109
Due to affiliates	32,165	30,162
Other	74	29
Total Current Liabilities	32,586	30,520
Long-Term Debt, less current portion	17	20
Deferred Revenue, less current portion	603	602
Other Liabilities	135	75
Stockholders' Equity (Deficit)	(25,680)	(24,063)
Total Liabilities and Stockholders’ Equity	7,661	7,154
Other Non-Guarantor Subsidiaries
Current Assets:
Cash and cash equivalents	270	335	292	86
Restricted cash and securities	6	7
Receivables, less allowances for doubtful accounts	594	621
Due from affiliates	0	7
Other	79	73
Total Current Assets	949	1,043
Property, Plant and Equipment, net	5,212	5,273
Restricted Cash and Securities	2	6
Goodwill and Other Intangibles Assets, net	2,387	2,404
Investment in Subsidiaries	0	0
Other Assets, net	241	252
Total Assets	8,791	8,978
Current Liabilities:
Accounts payable	581	723
Current portion of long-term debt	28	32
Accrued payroll and employee benefits	38	50
Accrued interest	1	1
Current portion of deferred revenue	122	142
Due to affiliates	228	0
Other	81	105
Total Current Liabilities	1,079	1,053
Long-Term Debt, less current portion	39	40
Deferred Revenue, less current portion	303	285
Other Liabilities	603	761
Stockholders' Equity (Deficit)	6,767	6,839
Total Liabilities and Stockholders’ Equity	8,791	8,978
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 affiliates	(32,393)	(30,162)
Other	0	0
Total Current Assets	(32,393)	(30,162)
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	0	0
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	(40,788)	28,984
Other Assets, net	0	0
Total Assets	(73,181)	(1,178)
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
Due to affiliates	(32,393)	(30,162)
Other	0	0
Total Current Liabilities	(32,393)	(30,162)
Long-Term Debt, less current portion	0	0
Deferred Revenue, less current portion	0	0
Other Liabilities	0	0
Stockholders' Equity (Deficit)	(40,788)	28,984
Total Liabilities and Stockholders’ Equity	$ (73,181)	$ (1,178)