Condensed Consolidating Financial Information - Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities of Continuing Operations	$ 578	$ 388	$ 339
Cash Flows from Investing Activities:
Capital expenditures	(743)	(494)	(435)
(Increase) Decrease in restricted cash and securities, net	20	(54)	3
Proceeds from the sale of property, plant and equipment and other assets	11	4	4
Investment in Global Crossing, net of cash acquired	0	146	0
Payments for other investing activities	(13)	0	0
Net Cash Used in Investing Activities in Investing Activities of Continuing Operations	(725)	(398)	(428)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	4,504.0	1,878.0	808.0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(4,302)	(1,617)	(930)
Proceeds from Stock Options Exercised	5	0	0
Increase (decrease) due from affiliates, net	0	0	0
Net Cash Provided by (Used in) Financing Activities of Continuing Operations	207	261	(122)
Net Cash Provided by (Used in) Discontinued Operations	0	51	(1)
Effect of Exchange Rates on Cash and Cash Equivalents	1	0	(8)
Net Change in Cash and Cash Equivalents	61	302	(220)
Cash and Cash Equivalents at Beginning of Year	918	616	836
Cash and Cash Equivalents at End of Year	979	918	616
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities of Continuing Operations	(165)	(176)	(156)
Cash Flows from Investing Activities:
Capital expenditures	0	0	0
(Increase) Decrease in restricted cash and securities, net	6	0	0
Proceeds from the sale of property, plant and equipment and other assets	0	0	0
Investment in Global Crossing, net of cash acquired		0
Payments for other investing activities	0
Net Cash Used in Investing Activities in Investing Activities of Continuing Operations	6	0	0
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	293.0	292.0	195.0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	(521)	(328)
Proceeds from Stock Options Exercised	5
Increase (decrease) due from affiliates, net	112	234	226
Net Cash Provided by (Used in) Financing Activities of Continuing Operations	410	5	93
Net Cash Provided by (Used in) Discontinued Operations		0	0
Effect of Exchange Rates on Cash and Cash Equivalents	0	0	0
Net Change in Cash and Cash Equivalents	251	(171)	(63)
Cash and Cash Equivalents at Beginning of Year	2	173	236
Cash and Cash Equivalents at End of Year	253	2	173
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities of Continuing Operations	(520)	(428)	(362)
Cash Flows from Investing Activities:
Capital expenditures	0	0	0
(Increase) Decrease in restricted cash and securities, net	0	0	0
Proceeds from the sale of property, plant and equipment and other assets	0	0	0
Investment in Global Crossing, net of cash acquired		0
Payments for other investing activities	0
Net Cash Used in Investing Activities in Investing Activities of Continuing Operations	0	0	0
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	4,211.0	1,586.0	613.0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(4,161)	(755)	(599)
Proceeds from Stock Options Exercised	0
Increase (decrease) due from affiliates, net	469	(404)	347
Net Cash Provided by (Used in) Financing Activities of Continuing Operations	519	427	361
Net Cash Provided by (Used in) Discontinued Operations		0	0
Effect of Exchange Rates on Cash and Cash Equivalents	0	0	0
Net Change in Cash and Cash Equivalents	(1)	(1)	(1)
Cash and Cash Equivalents at Beginning of Year	6	7	8
Cash and Cash Equivalents at End of Year	5	6	7
Level 3 Communications, LLC
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities of Continuing Operations	140	293	76
Cash Flows from Investing Activities:
Capital expenditures	(276)	(197)	(161)
(Increase) Decrease in restricted cash and securities, net	2	3	3
Proceeds from the sale of property, plant and equipment and other assets	0	1	2
Investment in Global Crossing, net of cash acquired		0
Payments for other investing activities	0
Net Cash Used in Investing Activities in Investing Activities of Continuing Operations	(274)	(193)	(156)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	0	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	0	(1)
Proceeds from Stock Options Exercised	0
Increase (decrease) due from affiliates, net	(98)	168	0
Net Cash Provided by (Used in) Financing Activities of Continuing Operations	(98)	168	(1)
Net Cash Provided by (Used in) Discontinued Operations		0	0
Effect of Exchange Rates on Cash and Cash Equivalents	0	0	0
Net Change in Cash and Cash Equivalents	(232)	268	(81)
Cash and Cash Equivalents at Beginning of Year	618	350	431
Cash and Cash Equivalents at End of Year	386	618	350
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities of Continuing Operations	1,123	699	781
Cash Flows from Investing Activities:
Capital expenditures	(467)	(297)	(274)
(Increase) Decrease in restricted cash and securities, net	12	(57)	0
Proceeds from the sale of property, plant and equipment and other assets	11	3	2
Investment in Global Crossing, net of cash acquired		146
Payments for other investing activities	(13)
Net Cash Used in Investing Activities in Investing Activities of Continuing Operations	(457)	(205)	(272)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	0	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(141)	(341)	(2)
Proceeds from Stock Options Exercised	0
Increase (decrease) due from affiliates, net	(483)	2	(573)
Net Cash Provided by (Used in) Financing Activities of Continuing Operations	(624)	(339)	(575)
Net Cash Provided by (Used in) Discontinued Operations		51	(1)
Effect of Exchange Rates on Cash and Cash Equivalents	1	0	(8)
Net Change in Cash and Cash Equivalents	43	206	(75)
Cash and Cash Equivalents at Beginning of Year	292	86	161
Cash and Cash Equivalents at End of Year	335	292	86
Eliminations
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities of Continuing Operations	0	0	0
Cash Flows from Investing Activities:
Capital expenditures	0	0	0
(Increase) Decrease in restricted cash and securities, net	0	0	0
Proceeds from the sale of property, plant and equipment and other assets	0	0	0
Investment in Global Crossing, net of cash acquired		0
Payments for other investing activities	0
Net Cash Used in Investing Activities in Investing Activities of Continuing Operations	0	0	0
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	0	0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	0	0
Proceeds from Stock Options Exercised	0
Increase (decrease) due from affiliates, net	0	0	0
Net Cash Provided by (Used in) Financing Activities of Continuing Operations	0	0	0
Net Cash Provided by (Used in) Discontinued Operations		0	0
Effect of Exchange Rates on Cash and Cash Equivalents	0	0	0
Net Change in Cash and Cash Equivalents	0	0	0
Cash and Cash Equivalents at Beginning of Year	0	0	0
Cash and Cash Equivalents at End of Year	$ 0	$ 0	$ 0