Condensed Consolidating Financial Information - Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	$ 223	$ 108
Cash Flows from Investing Activities:
Capital expenditures	(377)	(318)
Decrease in restricted cash and securities, net	8	4
Other	(14)	0
Proceeds from the sale of property, plant and equipment and other assets	0	5
Net Cash Provided by (Used in) Investing Activities	(383)	(309)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs	0	880
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(199)	(863)
Proceeds from stock options exercised	0	1
Increase (decrease) due from-to affiliates, net	0	0
Net Cash Provided by (Used in) Financing Activities	(199)	18
Effect of Exchange Rates on Cash and Cash Equivalents	(24)	(2)
Net Change in Cash and Cash Equivalents	(383)	(185)
Cash and Cash Equivalents at Beginning of Period	979	918
Cash and Cash Equivalents at End of Period	596	733
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	(86)	(144)
Cash Flows from Investing Activities:
Capital expenditures	0	0
Decrease in restricted cash and securities, net	5	3
Other	0
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash Provided by (Used in) Investing Activities	5	3
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs		0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(172)	0
Proceeds from stock options exercised		1
Increase (decrease) due from-to affiliates, net	9	140
Net Cash Provided by (Used in) Financing Activities	(163)	141
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	(244)	0
Cash and Cash Equivalents at Beginning of Period	253	2
Cash and Cash Equivalents at End of Period	9	2
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	(269)	(245)
Cash Flows from Investing Activities:
Capital expenditures	0	0
Decrease in restricted cash and securities, net	0	0
Other	0
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash Provided by (Used in) Investing Activities	0	0
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs		880
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(3)	(825)
Proceeds from stock options exercised		0
Increase (decrease) due from-to affiliates, net	272	190
Net Cash Provided by (Used in) Financing Activities	269	245
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	5	6
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	74	(66)
Cash Flows from Investing Activities:
Capital expenditures	(159)	(123)
Decrease in restricted cash and securities, net	0	0
Other	0
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash Provided by (Used in) Investing Activities	(159)	(123)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs		0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(4)	0
Proceeds from stock options exercised		0
Increase (decrease) due from-to affiliates, net	60	(13)
Net Cash Provided by (Used in) Financing Activities	56	(13)
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	(29)	(202)
Cash and Cash Equivalents at Beginning of Period	386	618
Cash and Cash Equivalents at End of Period	357	416
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	504	563
Cash Flows from Investing Activities:
Capital expenditures	(218)	(195)
Decrease in restricted cash and securities, net	3	1
Other	(14)
Proceeds from the sale of property, plant and equipment and other assets		5
Net Cash Provided by (Used in) Investing Activities	(229)	(189)
Cash Flows from Financing Activities:
Long-term debt borrowings, net of issuance costs		0
Payments on and repurchases of long-term debt, including current portions and refinancing costs	(20)	(38)
Proceeds from stock options exercised		0
Increase (decrease) due from-to affiliates, net	(341)	(317)
Net Cash Provided by (Used in) Financing Activities	(361)	(355)
Effect of Exchange Rates on Cash and Cash Equivalents	(24)	(2)
Net Change in Cash and Cash Equivalents	(110)	17
Cash and Cash Equivalents at Beginning of Period	335	292
Cash and Cash Equivalents at End of Period	225	309
Eliminations
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	0	0
Cash Flows from Investing Activities:
Capital expenditures	0	0
Decrease in restricted cash and securities, net	0	0
Other	0
Proceeds from the sale of property, plant and equipment and other assets		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
Payments on and repurchases of long-term debt, including current portions and refinancing costs	0	0
Proceeds from stock options exercised		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