Condensed Consolidating Financial Information - Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 729	$ 631	$ 507	$ 979
Restricted cash and securities	1,020	7
Receivables, less allowances for doubtful accounts	678	673
Due from affiliates	0	0
Other	173	143
Total Current Assets	2,600	1,454
Property, Plant and Equipment, net	8,268	8,240
Restricted Cash and Securities	21	23
Goodwill and Other Intangibles Assets, net	2,724	2,782
Investment in Subsidiaries	0	0
Other Assets, net	370	375
Total Assets	13,983	12,874
Liabilities and Stockholders' Equity:
Accounts payable	607	625
Current portion of long-term debt	502	31
Accrued payroll and employee benefits	165	209
Accrued interest	184	160
Current portion of deferred revenue	244	253
Due to affiliates	0	0
Other	151	168
Total Current Liabilities	1,853	1,446
Long-Term Debt, less current portion	8,856	8,331
Deferred Revenue, less current portion	877	906
Other Liabilities	749	780
Commitments and Contingencies	0	0
Stockholders' Equity (Deficit)	1,648	1,411
Total Liabilities and Stockholders’ Equity (Deficit)	13,983	12,874
Level 3 Communications, Inc.
Current Assets:
Cash and cash equivalents	7	8	9	253
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from affiliates	16,348	15,507
Other	3	2
Total Current Assets	16,358	15,517
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	3	3
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	10,127	10,039
Other Assets, net	8	10
Total Assets	26,496	25,569
Liabilities and Stockholders' Equity:
Accounts payable	2	0
Current portion of long-term debt	475	0
Accrued payroll and employee benefits	0	0
Accrued interest	46	30
Current portion of deferred revenue	0	0
Due to affiliates	0	0
Other	0	0
Total Current Liabilities	523	30
Long-Term Debt, less current portion	898	1,370
Deferred Revenue, less current portion	0	0
Other Liabilities	15	15
Commitments and Contingencies
Stockholders' Equity (Deficit)	25,060	24,154
Total Liabilities and Stockholders’ Equity (Deficit)	26,496	25,569
Level 3 Financing, Inc.
Current Assets:
Cash and cash equivalents	5	6	6	5
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from affiliates	17,921	16,886
Other	16	15
Total Current Assets	17,942	16,907
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	0	0
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	8,794	27,014
Other Assets, net	100	113
Total Assets	26,836	44,034
Liabilities and Stockholders' Equity:
Accounts payable	0	2
Current portion of long-term debt	0	0
Accrued payroll and employee benefits	0	0
Accrued interest	131	129
Current portion of deferred revenue	0	0
Due to affiliates	0	0
Other	1	13
Total Current Liabilities	132	144
Long-Term Debt, less current portion	6,907	6,905
Deferred Revenue, less current portion	0	0
Other Liabilities	29	27
Commitments and Contingencies
Stockholders' Equity (Deficit)	19,768	36,958
Total Liabilities and Stockholders’ Equity (Deficit)	26,836	44,034
Level 3 Communications, LLC
Current Assets:
Cash and cash equivalents	524	347	289	386
Restricted cash and securities	1	1
Receivables, less allowances for doubtful accounts	48	79
Due from affiliates	0	0
Other	63	47
Total Current Assets	636	474
Property, Plant and Equipment, net	3,112	3,028
Restricted Cash and Securities	16	18
Goodwill and Other Intangibles Assets, net	376	395
Investment in Subsidiaries	3,731	3,735
Other Assets, net	10	11
Total Assets	7,881	7,661
Liabilities and Stockholders' Equity:
Accounts payable	236	42
Current portion of long-term debt	2	3
Accrued payroll and employee benefits	128	171
Accrued interest	0	0
Current portion of deferred revenue	124	131
Due to affiliates	33,869	32,165
Other	67	74
Total Current Liabilities	34,426	32,586
Long-Term Debt, less current portion	17	17
Deferred Revenue, less current portion	570	603
Other Liabilities	119	135
Commitments and Contingencies
Stockholders' Equity (Deficit)	(27,251)	(25,680)
Total Liabilities and Stockholders’ Equity (Deficit)	7,881	7,661
Other Non-Guarantor Subsidiaries
Current Assets:
Cash and cash equivalents	193	270	203	335
Restricted cash and securities	1,019	6
Receivables, less allowances for doubtful accounts	630	594
Due from affiliates	0	0
Other	91	79
Total Current Assets	1,933	949
Property, Plant and Equipment, net	5,156	5,212
Restricted Cash and Securities	2	2
Goodwill and Other Intangibles Assets, net	2,348	2,387
Investment in Subsidiaries	0	0
Other Assets, net	252	241
Total Assets	9,691	8,791
Liabilities and Stockholders' Equity:
Accounts payable	369	581
Current portion of long-term debt	25	28
Accrued payroll and employee benefits	37	38
Accrued interest	7	1
Current portion of deferred revenue	120	122
Due to affiliates	400	228
Other	83	81
Total Current Liabilities	1,041	1,079
Long-Term Debt, less current portion	1,034	39
Deferred Revenue, less current portion	307	303
Other Liabilities	586	603
Commitments and Contingencies
Stockholders' Equity (Deficit)	6,723	6,767
Total Liabilities and Stockholders’ Equity (Deficit)	9,691	8,791
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	(34,269)	(32,393)
Other	0	0
Total Current Assets	(34,269)	(32,393)
Property, Plant and Equipment, net	0	0
Restricted Cash and Securities	0	0
Goodwill and Other Intangibles Assets, net	0	0
Investment in Subsidiaries	(22,652)	(40,788)
Other Assets, net	0	0
Total Assets	(56,921)	(73,181)
Liabilities and Stockholders' Equity:
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	(34,269)	(32,393)
Other	0	0
Total Current Liabilities	(34,269)	(32,393)
Long-Term Debt, less current portion	0	0
Deferred Revenue, less current portion	0	0
Other Liabilities	0	0
Commitments and Contingencies	0
Stockholders' Equity (Deficit)	(22,652)	(40,788)
Total Liabilities and Stockholders’ Equity (Deficit)	$ (56,921)	$ (73,181)