Condensed Consolidating Financial Information - Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	$ 765	$ 327
Cash Flows from Investing Activities:
Capital expenditures	(608)	(571)
(Increase) decrease in restricted cash and securities, net	(10)	13
Proceeds from Sale of Property, Plant, and Equipment and other assets	3	16
Other	2	14
Net Cash Provided by (Used in) Investing Activities	(617)	(556)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	(1)	590
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(8)	(810)
Increase (decrease) due from-to affiliates, net	0	0
Net Cash Provided by (Used in) Financing Activities	(9)	(220)
Effect of Exchange Rates on Cash and Cash Equivalents	(41)	(23)
Net Change in Cash and Cash Equivalents	98	(472)
Cash and Cash Equivalents at Beginning of Period	631	979
Cash and Cash Equivalents at End of Period	729	507
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	(91)	(105)
Cash Flows from Investing Activities:
Capital expenditures	0	0
(Increase) decrease in restricted cash and securities, net	0	9
Proceeds from Sale of Property, Plant, and Equipment and other assets	0	0
Other	0	0
Net Cash Provided by (Used in) Investing Activities	0	9
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	(172)
Increase (decrease) due from-to affiliates, net	90	24
Net Cash Provided by (Used in) Financing Activities	90	(148)
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	(1)	(244)
Cash and Cash Equivalents at Beginning of Period	8	253
Cash and Cash Equivalents at End of Period	7	9
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	(336)	(441)
Cash Flows from Investing Activities:
Capital expenditures	0	0
(Increase) decrease in restricted cash and securities, net	0	0
Proceeds from Sale of Property, Plant, and Equipment and other assets	0	0
Other	0	0
Net Cash Provided by (Used in) Investing Activities	0	0
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	590
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	(607)
Increase (decrease) due from-to affiliates, net	335	459
Net Cash Provided by (Used in) Financing Activities	335	442
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	(1)	1
Cash and Cash Equivalents at Beginning of Period	6	5
Cash and Cash Equivalents at End of Period	5	6
Level 3 Communications, LLC
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	443	298
Cash Flows from Investing Activities:
Capital expenditures	(261)	(235)
(Increase) decrease in restricted cash and securities, net	1	0
Proceeds from Sale of Property, Plant, and Equipment and other assets	0	0
Other	0	0
Net Cash Provided by (Used in) Investing Activities	(260)	(235)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	(4)
Increase (decrease) due from-to affiliates, net	(6)	(156)
Net Cash Provided by (Used in) Financing Activities	(6)	(160)
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	177	(97)
Cash and Cash Equivalents at Beginning of Period	347	386
Cash and Cash Equivalents at End of Period	524	289
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	749	575
Cash Flows from Investing Activities:
Capital expenditures	(347)	(336)
(Increase) decrease in restricted cash and securities, net	(11)	4
Proceeds from Sale of Property, Plant, and Equipment and other assets	3	16
Other	2	14
Net Cash Provided by (Used in) Investing Activities	(357)	(330)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	(1)	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(8)	(27)
Increase (decrease) due from-to affiliates, net	(419)	(327)
Net Cash Provided by (Used in) Financing Activities	(428)	(354)
Effect of Exchange Rates on Cash and Cash Equivalents	(41)	(23)
Net Change in Cash and Cash Equivalents	(77)	(132)
Cash and Cash Equivalents at Beginning of Period	270	335
Cash and Cash Equivalents at End of Period	193	203
Eliminations
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	0	0
Cash Flows from Investing Activities:
Capital expenditures	0	0
(Increase) decrease in restricted cash and securities, net	0	0
Proceeds from Sale of Property, Plant, and Equipment and other assets	0	0
Other	0	0
Net Cash Provided by (Used in) Investing Activities	0	0
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	0
Increase (decrease) due from-to affiliates, net	0	0
Net Cash Provided by (Used in) Financing Activities	0	0
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	0	0
Cash and Cash Equivalents at Beginning of Period	0	0
Cash and Cash Equivalents at End of Period	$ 0	$ 0