Long-Term Debt - Textuals (Details)	1 Months Ended	3 Months Ended								11 Months Ended	12 Months Ended						24 Months Ended	65 Months Ended
	Mar. 31, 2007 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2012	Dec. 31, 2015 USD ($) days	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Oct. 04, 2013	Aug. 01, 2013	Dec. 31, 2011	Oct. 04, 2013	Jul. 31, 2012 USD ($)	Nov. 13, 2015 USD ($)	May. 08, 2015 USD ($)	Apr. 28, 2015 USD ($)	Jan. 29, 2015 USD ($)	Dec. 01, 2014 USD ($)	Oct. 31, 2014 USD ($)	Aug. 12, 2014 USD ($)	Jan. 01, 2014 USD ($)	Jan. 13, 2012 USD ($)	Jun. 09, 2011 USD ($)	Mar. 04, 2011 USD ($)
Long-term debt
Debt Conversion, Converted Instrument, Amount											$ 333,000,000	$ 142,000,000	$ 200,000,000
Debt Issuance Cost											50,000,000	49,000,000	27,000,000
Debt Instrument, Unamortized Debt Issuance Costs		$ 128,000,000				$ 145,000,000					128,000,000	145,000,000
Debt Instrument, Net Proceeds											4,832,000,000	589,000,000	1,502,000,000
Accrued interest conversion into equity											10,000,000	2,000,000	3,000,000
Loss on extinguishment of debt		(55,000,000)	$ 0	$ (163,000,000)	$ 0	(53,000,000)	$ 0	$ 0	$ 0		$ (218,000,000)	(53,000,000)	(84,000,000)
Debt instrument, redemption period notice minimum (number of days) | days											30
Debt instrument, redemption period notice maximum (number of days) | days											60
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
2013		15,000,000									$ 15,000,000
2014		7,000,000									7,000,000
2015		307,000,000									307,000,000
2016		822,000,000									822,000,000
2017		2,579,000,000									2,579,000,000
Thereafter		7,295,000,000									7,295,000,000
Total Debt Obligations		11,025,000,000									11,025,000,000
Long-term Debt, Gross		$ 11,025,000,000				11,366,000,000					11,025,000,000	11,366,000,000
Level 3 Communications, Inc.
Long-term debt
Debt Instrument, Net Proceeds											$ 0	590,000,000	0
Level 3 Financing [Member]
Long-term debt
Debt Instrument, Description of Variable Rate Basis	three month LIBOR										three month LIBOR
Derivative, Notional Amount	$ 1,000,000,000
Guarantor Subsidiaries [Member]
Long-term debt
Debt Instrument, Net Proceeds											$ 4,832,000,000	0	$ 1,502,000,000
2.0 Billion Tranche B-II 2022 Term Loan [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		3.50%									3.50%
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 2,000,000,000				$ 0					$ 2,000,000,000	$ 0
2.0 Billion Tranche B-II 2022 Term Loan [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																				$ 2,000,000,000
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Upfront basis point			25
TrancheB2022TermLoanTotal [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		2,000,000,000									2,000,000,000
TrancheB2022TermLoanTotal [Member] | Guarantor Subsidiaries [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		2,000,000,000									2,000,000,000
Tranche B 2022 Term Loans [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)						4.50%						4.50%
Loss on extinguishment of debt				27,000,000
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		0				$ 2,000,000,000					0	$ 2,000,000,000
Tranche B 2022 Term Loans [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																								$ 2,000,000,000
Loss on extinguishment of debt											27,000,000
Tranche B 2022 Term Loans [Member] | Guarantor Subsidiaries [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Tranche B Term Loan 2022 upfront payment percentage																								0.75%
SeniorNotes6Point125PercentDue2021 [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 640,000,000				640,000,000					$ 640,000,000	640,000,000
SeniorNotes6Point125PercentDue2021 [Member] | Level 3 Financing [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		6.125%									6.125%
Senior Notes 7 Percent Due 2020 [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 775,000,000				775,000,000					$ 775,000,000	775,000,000
Senior Notes 7 Percent Due 2020 [Member] | Level 3 Financing [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		7.00%									7.00%
TrancheB2020TermLoanTotal [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 1,796,000,000				1,796,000,000					$ 1,796,000,000	1,796,000,000
TrancheB2020TermLoanTotal [Member] | Guarantor Subsidiaries [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross																										$ 1,796,000,000
Tranche B III 2019 and Tranche B 2020 Term Loans [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		4.00%									4.00%
Tranche A Term Loan
Long-term debt
Debt Instrument, Description of Variable Rate Basis																LIBOR
Debt instrument, Interest spread on debt (as percent)																		2.25%
Tranche B II Term Loan
Long-term debt
Debt Instrument, Description of Variable Rate Basis																LIBOR
Debt instrument, basis floor (as percent)																1.50%
Debt instrument, Interest spread on debt (as percent)																	4.25%
Tranche B III Term Loan
Long-term debt
Debt Instrument, Description of Variable Rate Basis																LIBOR
Debt instrument, basis floor (as percent)																1.50%
Debt instrument, Interest spread on debt (as percent)										4.25%
Tranche B 2016 Term Loan
Long-term debt
Debt Instrument, Description of Variable Rate Basis											LIBOR
Debt instrument, basis floor (as percent)		1.50%									1.50%
Debt instrument, Interest spread on debt (as percent)															3.25%
Tranche B 2019 Term Loan
Long-term debt
Debt Instrument, Description of Variable Rate Basis											LIBOR
Debt instrument, basis floor (as percent)		1.50%									1.50%
Debt instrument, Interest spread on debt (as percent)															3.75%
TrancheBIII2019TermLoan [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 815,000,000				$ 815,000,000					$ 815,000,000	$ 815,000,000
TrancheBIII2019TermLoan [Member] | Guarantor Subsidiaries [Member]
Long-term debt
Debt Instrument, Face Amount																										$ 815,000,000
Tranche B-II 2019 Term Loan
Long-term debt
Debt Instrument, Description of Variable Rate Basis											LIBOR
Debt instrument, basis floor (as percent)		1.50%									1.50%
Debt instrument, Interest spread on debt (as percent)														3.25%
Floating Rate Senior Notes due 2018 [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		4.101%				3.826%					4.101%	3.826%
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 300,000,000				$ 300,000,000					$ 300,000,000	$ 300,000,000
Floating Rate Senior Notes due 2015
Long-term debt
Debt instrument, stated interest rate (as a percent)		3.846%									3.846%					3.826%
Senior Notes 11 Point 875 Percent Due 2019 [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		11.875%									11.875%
Senior Notes 11 Point 875 Percent Due 2019 [Member] | Level 3 Communications, Inc.
Long-term debt
Debt instrument, stated interest rate (as a percent)		11.875%									11.875%
Debt Instrument, Redemption Price, Percentage						106.859%
Loss on extinguishment of debt						$ (53,000,000)
Senior Notes due 2019 (9.375%)
Long-term debt
Debt instrument, stated interest rate (as a percent)		9.375%									9.375%
Loss on extinguishment of debt				(36,000,000)							$ (36,000,000)
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 0				500,000,000					$ 0	500,000,000
Senior Notes due 2019 (9.375%) | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																													$ 500,000,000
Debt instrument, stated interest rate (as a percent)		9.375%									9.375%
Senior Notes 5point 625Percent Due 2023 [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 500,000,000				0					$ 500,000,000	0
Senior Notes 5point 625Percent Due 2023 [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																						$ 500,000,000
Debt instrument, stated interest rate (as a percent)		5.625%									5.625%
Senior Notes due 2019 (8.125%)
Long-term debt
Debt instrument, stated interest rate (as a percent)		8.125%									8.125%
Loss on extinguishment of debt				(82,000,000)
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 0				1,200,000,000					$ 0	1,200,000,000
Senior Notes due 2019 (8.125%) | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																												$ 1,200,000,000
Debt instrument, stated interest rate (as a percent)		8.125%									8.125%
Loss on extinguishment of debt											$ (82,000,000)
Senior Notes due 2019 (8.875%)
Long-term debt
Debt instrument, stated interest rate (as a percent)		8.875%									8.875%
Loss on extinguishment of debt				$ (18,000,000)
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 0				300,000,000					$ 0	300,000,000
Senior Notes due 2019 (8.875%) | Level 3 Communications, Inc.
Long-term debt
Debt instrument, stated interest rate (as a percent)		8.875%									8.875%
Senior Notes due 2019 (8.875%) | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																		$ 300,000,000
Loss on extinguishment of debt											$ (18,000,000)
Senior Notes 5point 125Percent Due 2023 [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 700,000,000				0					$ 700,000,000	0
Senior Notes 5point 125Percent Due 2023 [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																					$ 700,000,000
Debt instrument, stated interest rate (as a percent)		5.125%									5.125%
Senior Notes 5point 375Percent Due 2025 [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 800,000,000				0					$ 800,000,000	0
Senior Notes 5point 375Percent Due 2025 [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																					$ 800,000,000
Debt instrument, stated interest rate (as a percent)		5.375%									5.375%
Senior Notes 8 Point 625 Percent Due 2020 [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		8.625%									8.625%
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 0				900,000,000					$ 0	900,000,000
Senior Notes 8 Point 625 Percent Due 2020 [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																											$ 900,000,000
Debt instrument, stated interest rate (as a percent)		8.625%									8.625%
Senior Notes 5point 375Percent Due 2024 [Member]
Long-term debt
Loss on extinguishment of debt		$ (55,000,000)
Senior Notes 5point 375Percent Due 2024 [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Face Amount																			$ 900,000,000
Debt instrument, stated interest rate (as a percent)		5.375%									5.375%
Loss on extinguishment of debt											$ (55,000,000)
Senior Notes 5.375percent Due 2022 [Member]
Long-term debt
Debt Instrument, Face Amount		$ 1,000,000,000									$ 1,000,000,000														$ 1,000,000,000
Debt instrument, stated interest rate (as a percent)		5.375%									5.375%
Senior Notes 5.375percent Due 2022 [Member] | Level 3 Financing [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)		5.375%									5.375%
Senior Notes 5.375percent Due 2022 [Member] | Level 3 Escrow II, Inc. [Member]
Long-term debt
Debt Instrument, Face Amount																									$ 1,000,000,000
Senior Notes 5point75Percent Due 2022 [Member]
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 600,000,000				600,000,000					$ 600,000,000	600,000,000
Senior Notes 5point75Percent Due 2022 [Member] | Level 3 Communications, Inc.
Long-term debt
Debt Instrument, Face Amount																							$ 600,000,000
Debt instrument, stated interest rate (as a percent)		5.75%									5.75%
Convertible Senior Notes 7 Percent Due 2015 [Member]
Long-term debt
Debt Conversion, Original Debt, Amount					333,000,000	142,000,000
Debt Conversion, Converted Instrument, Amount					$ 1,000	$ 1,000
Debt conversion, shares issued upon conversion (in shares) | shares					12,000,000	5,000,000
Conversion of Stock, Shares Converted | shares					37	37
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 0				$ 58,000,000					$ 0	58,000,000
Convertible Senior Notes 7 Percent Due 2015 [Member] | Level 3 Communications, Inc.
Long-term debt
Debt instrument, stated interest rate (as a percent)		7.00%									7.00%
Convertible Senior Notes due 2015 Series B (7.0%)
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Long-term Debt, Gross		$ 0				275,000,000					$ 0	275,000,000
Convertible Senior Notes due 2015 Series B (7.0%) | Level 3 Communications, Inc.
Long-term debt
Debt instrument, stated interest rate (as a percent)		7.00%									7.00%
Capital Leases
Long-term debt
Debt instrument, weighted average interest rate (as percent)		5.90%									5.90%
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Total Debt Obligations		$ 199,000,000									$ 199,000,000
Long-term Debt, Gross		$ 199,000,000				$ 207,000,000					$ 199,000,000	$ 207,000,000
Other
Long-term debt
Debt instrument, weighted average interest rate (as percent)		5.00%									5.00%
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Total Debt Obligations		$ 1,000,000									$ 1,000,000
London Interbank Offered Rate (LIBOR) [Member] | 2.0 Billion Tranche B-II 2022 Term Loan [Member] | Level 3 Financing [Member]
Long-term debt
Debt Instrument, Description of Variable Rate Basis		LIBOR	LIBOR			LIBOR
Debt instrument, Interest spread on debt (as percent)			2.75%
Future contractual maturities of long-term debt and capital leases (excluding issue discounts, premiums and fair value adjustments)
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum			0.75%
London Interbank Offered Rate (LIBOR) [Member] | Tranche B 2022 Term Loans [Member] | Guarantor Subsidiaries [Member]
Long-term debt
Debt instrument, Interest spread on debt (as percent)						3.50%
London Interbank Offered Rate (LIBOR) [Member] | Tranche B 2022 Term Loans [Member] | Guarantor Subsidiaries [Member] | Minimum [Member]
Long-term debt
Debt instrument, stated interest rate (as a percent)																								1.00%