Condensed Consolidating Financial Information - Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 637	$ 631	$ 596	$ 979
Restricted cash and securities	6	7
Receivables, less allowances for doubtful accounts	722	673
Due from affiliates	0	0
Other	174	143
Total Current Assets	1,539	1,454
Property, Plant and Equipment, net	8,355	8,240
Restricted Cash and Securities	23	23
Goodwill and Other Intangibles Assets, net	2,747	2,782
Investment in Subsidiaries	0	0
Other Assets, net	364	375
Total Assets	13,028	12,874
Liabilities and Stockholders' Equity:
Accounts payable	613	625
Current portion of long-term debt	503	31
Accrued payroll and employee benefits	145	209
Accrued interest	166	160
Current portion of deferred revenue	258	253
Due to affiliates	0	0
Other	139	168
Total Current Liabilities	1,824	1,446
Long-Term Debt, less current portion	7,855	8,331
Deferred Revenue, less current portion	885	906
Other Liabilities	785	780
Commitments and Contingencies	0	0
Stockholders' Equity (Deficit)	1,679	1,411
Total Liabilities and Stockholders’ Equity (Deficit)	13,028	12,874
Level 3 Communications, Inc.
Current Assets:
Cash and cash equivalents	8	8	9	253
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from affiliates	16,060	15,507
Other	4	2
Total Current Assets	16,072	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	10,099	10,039
Other Assets, net	8	10
Total Assets	26,182	25,569
Liabilities and Stockholders' Equity:
Accounts payable	0	0
Current portion of long-term debt	474	0
Accrued payroll and employee benefits	0	0
Accrued interest	30	30
Current portion of deferred revenue	0	0
Due to affiliates	0	0
Other	0	0
Total Current Liabilities	504	30
Long-Term Debt, less current portion	898	1,370
Deferred Revenue, less current portion	0	0
Other Liabilities	15	15
Commitments and Contingencies	0
Stockholders' Equity (Deficit)	24,765	24,154
Total Liabilities and Stockholders’ Equity (Deficit)	26,182	25,569
Level 3 Financing, Inc.
Current Assets:
Cash and cash equivalents	6	6	5	5
Restricted cash and securities	0	0
Receivables, less allowances for doubtful accounts	0	0
Due from affiliates	17,582	16,886
Other	16	15
Total Current Assets	17,604	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	8,959	27,014
Other Assets, net	105	113
Total Assets	26,668	44,034
Liabilities and Stockholders' Equity:
Accounts payable	1	2
Current portion of long-term debt	0	0
Accrued payroll and employee benefits	0	0
Accrued interest	136	129
Current portion of deferred revenue	0	0
Due to affiliates	0	0
Other	2	13
Total Current Liabilities	139	144
Long-Term Debt, less current portion	6,906	6,905
Deferred Revenue, less current portion	0	0
Other Liabilities	29	27
Commitments and Contingencies	0
Stockholders' Equity (Deficit)	19,594	36,958
Total Liabilities and Stockholders’ Equity (Deficit)	26,668	44,034
Level 3 Communications, LLC
Current Assets:
Cash and cash equivalents	414	347	357	386
Restricted cash and securities	1	1
Receivables, less allowances for doubtful accounts	85	79
Due from affiliates	(32,979)	0
Other	68	47
Total Current Assets	(32,411)	474
Property, Plant and Equipment, net	3,084	3,028
Restricted Cash and Securities	18	18
Goodwill and Other Intangibles Assets, net	380	395
Investment in Subsidiaries	3,734	3,735
Other Assets, net	9	11
Total Assets	(25,186)	7,661
Liabilities and Stockholders' Equity:
Accounts payable	284	42
Current portion of long-term debt	2	3
Accrued payroll and employee benefits	104	171
Accrued interest	0	0
Current portion of deferred revenue	120	131
Due to affiliates	0	32,165
Other	71	74
Total Current Liabilities	581	32,586
Long-Term Debt, less current portion	16	17
Deferred Revenue, less current portion	573	603
Other Liabilities	125	135
Commitments and Contingencies	0
Stockholders' Equity (Deficit)	(26,481)	(25,680)
Total Liabilities and Stockholders’ Equity (Deficit)	(25,186)	7,661
Other Non-Guarantor Subsidiaries
Current Assets:
Cash and cash equivalents	209	270	225	335
Restricted cash and securities	5	6
Receivables, less allowances for doubtful accounts	637	594
Due from affiliates	(663)	0
Other	86	79
Total Current Assets	274	949
Property, Plant and Equipment, net	5,271	5,212
Restricted Cash and Securities	2	2
Goodwill and Other Intangibles Assets, net	2,367	2,387
Investment in Subsidiaries	0	0
Other Assets, net	242	241
Total Assets	8,156	8,791
Liabilities and Stockholders' Equity:
Accounts payable	328	581
Current portion of long-term debt	27	28
Accrued payroll and employee benefits	41	38
Accrued interest	0	1
Current portion of deferred revenue	138	122
Due to affiliates	0	228
Other	66	81
Total Current Liabilities	600	1,079
Long-Term Debt, less current portion	35	39
Deferred Revenue, less current portion	312	303
Other Liabilities	616	603
Commitments and Contingencies	0
Stockholders' Equity (Deficit)	6,593	6,767
Total Liabilities and Stockholders’ Equity (Deficit)	8,156	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	0	(32,393)
Other	0	0
Total Current Assets	0	(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	(22,792)	(40,788)
Other Assets, net	0	0
Total Assets	(22,792)	(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	0	(32,393)
Other	0	0
Total Current Liabilities	0	(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)	(22,792)	(40,788)
Total Liabilities and Stockholders’ Equity (Deficit)	$ (22,792)	$ (73,181)