Condensed Consolidating Financial Information - Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	$ 7	$ (75)
Cash Flows from Investing Activities:
Capital expenditures	(169)	(138)
Decrease in restricted cash and securities, net	3	1
Proceeds from the sale of property, plant and equipment and other assets	0	5
Net Cash Used in Investing Activities	(166)	(132)
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	(186)	(847)
Proceeds from stock options exercised	0	1
Increase (decrease) due from affiliates, net	0	0
Net Cash Provided by (Used in) Financing Activities	(186)	34
Effect of Exchange Rates on Cash and Cash Equivalents	(24)	3
Net Change in Cash and Cash Equivalents	(369)	(170)
Cash and Cash Equivalents at Beginning of Period	979	918
Cash and Cash Equivalents at End of Period	610	748
Level 3 Communications, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	(30)	(36)
Cash Flows from Investing Activities:
Capital expenditures	0	0
Decrease in restricted cash and securities, net	0	0
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash 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	(172)	0
Proceeds from stock options exercised		1
Increase (decrease) due from affiliates, net	1	34
Net Cash Provided by (Used in) Financing Activities	(171)	35
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	(201)	(1)
Cash and Cash Equivalents at Beginning of Period	253	2
Cash and Cash Equivalents at End of Period	52	1
Level 3 Financing, Inc.
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	(169)	(184)
Cash Flows from Investing Activities:
Capital expenditures	0	0
Decrease in restricted cash and securities, net	0	0
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash 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	(2)	(825)
Proceeds from stock options exercised		0
Increase (decrease) due from affiliates, net	171	129
Net Cash Provided by (Used in) Financing Activities	169	184
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	(15)	(74)
Cash Flows from Investing Activities:
Capital expenditures	(74)	(61)
Decrease in restricted cash and securities, net	0	1
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash Used in Investing Activities	(74)	(60)
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 affiliates, net	35	(63)
Net Cash Provided by (Used in) Financing Activities	31	(63)
Effect of Exchange Rates on Cash and Cash Equivalents	0	0
Net Change in Cash and Cash Equivalents	(58)	(197)
Cash and Cash Equivalents at Beginning of Period	386	618
Cash and Cash Equivalents at End of Period	328	421
Other Non-Guarantor Subsidiaries
Condensed Consolidating Financial Information
Net Cash Provided by (Used in) Operating Activities	221	219
Cash Flows from Investing Activities:
Capital expenditures	(95)	(77)
Decrease in restricted cash and securities, net	3	0
Proceeds from the sale of property, plant and equipment and other assets		5
Net Cash Used in Investing Activities	(92)	(72)
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	(8)	(22)
Proceeds from stock options exercised		0
Increase (decrease) due from affiliates, net	(207)	(100)
Net Cash Provided by (Used in) Financing Activities	(215)	(122)
Effect of Exchange Rates on Cash and Cash Equivalents	(24)	3
Net Change in Cash and Cash Equivalents	(110)	28
Cash and Cash Equivalents at Beginning of Period	335	292
Cash and Cash Equivalents at End of Period	225	320
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
Proceeds from the sale of property, plant and equipment and other assets		0
Net Cash 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 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