Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateTerms
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount (premium).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28567-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_LongTermDebtAndCapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

Name:	us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Long-Term Debt - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Jan. 01, 2014
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	7.00%			7.00%
Total Debt Obligations	$ 11,009		$ 11,025	$ 11,009
Total Unamortized (Discount) Premium	(13)		16	(13)
Unamortized Debt Issuance Expense	(112)		(128)	(112)
Less current portion	(7)		(15)	(7)
Long-Term Debt, less current portion	10,877		10,866	10,877
TrancheBIII2019TermLoan [Member]
Long-term debt
Total Debt Obligations	815		815	815
TrancheB2020TermLoanTotal [Member]
Long-term debt
Total Debt Obligations	$ 1,796		1,796	$ 1,796
2.0 Billion Tranche B-II 2022 Term Loan [Member]
Long-term debt
Debt Instrument, Interest Rate Terms				LIBOR +2.75%
Debt Instrument, Interest Rate, Stated Percentage	3.50%			3.50%
Total Debt Obligations	$ 2,000		$ 2,000	$ 2,000
Floating Rate Senior Notes due 2018 [Member]
Long-term debt
Debt Instrument, Interest Rate Terms				6-Month LIBOR +3.50%
Debt Instrument, Interest Rate, Stated Percentage	4.762%		4.101%	4.762%
Total Debt Obligations	$ 300		$ 300	$ 300
Senior Notes due 2020 (7.0%)
Long-term debt
Total Debt Obligations	0		775	0
Senior Notes due 2021 (6.125%)
Long-term debt
Total Debt Obligations	$ 640		640	$ 640
Senior Notes 5.375percent Due 2022 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.375%			5.375%
Total Debt Obligations	$ 1,000		1,000	$ 1,000
Senior Notes 5point 625Percent Due 2023 [Member]
Long-term debt
Total Debt Obligations	500		500	500
Senior Notes 5point 125Percent Due 2023 [Member]
Long-term debt
Total Debt Obligations	700		700	700
Senior Notes 5point 375Percent Due 2025 [Member]
Long-term debt
Total Debt Obligations	800		800	800
Senior Notes 5.375 Percent Due 2024 [Member]
Long-term debt
Total Debt Obligations	$ 900		900	$ 900
Convertible Senior Notes 7 Percent Due 2015 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.25%			5.25%
Total Debt Obligations	$ 775		0	$ 775
Senior Notes 5point75Percent Due 2022 [Member]
Long-term debt
Total Debt Obligations	600		600	600
Capital Leases
Long-term debt
Total Debt Obligations	$ 183		199	$ 183
Tranche B III 2019 and Tranche B 2020 Term Loans [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	4.00%			4.00%
Level 3 Financing [Member] \| Senior Notes due 2020 (7.0%)
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	7.00%			7.00%
Level 3 Financing [Member] \| Senior Notes due 2021 (6.125%)
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	6.125%			6.125%
Level 3 Financing [Member] \| Senior Notes 5.375percent Due 2022 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.375%			5.375%
Level 3 Financing [Member] \| Senior Notes 5point 625Percent Due 2023 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.625%			5.625%
Level 3 Financing [Member] \| Senior Notes 5point 125Percent Due 2023 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.125%			5.125%
Level 3 Financing [Member] \| Senior Notes 5point 375Percent Due 2025 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.375%			5.375%
Level 3 Financing [Member] \| Senior Notes 5.375 Percent Due 2024 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.375%			5.375%
Guarantor Subsidiaries [Member]
Long-term debt
Less current portion	$ (2)		(2)	$ (2)
Long-Term Debt, less current portion	13		15	$ 13
Guarantor Subsidiaries [Member] \| TrancheBIII2019TermLoan [Member]
Long-term debt
Debt Instrument, Interest Rate Terms				LIBOR +3.00%
Guarantor Subsidiaries [Member] \| TrancheB2020TermLoanTotal [Member]
Long-term debt
Debt Instrument, Interest Rate Terms				LIBOR +3.00%
Total Debt Obligations					$ 1,796
Level 3 Communications, Inc.
Long-term debt
Less current portion	0		0	$ 0
Long-Term Debt, less current portion	$ 592		$ 591	$ 592
Level 3 Communications, Inc. \| Convertible Senior Notes 7 Percent Due 2015 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	7.00%			7.00%
Level 3 Communications, Inc. \| Senior Notes 5point75Percent Due 2022 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	5.75%			5.75%
London Interbank Offered Rate (LIBOR) [Member] \| TrancheBIII2019TermLoan [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	3.00%			3.00%
London Interbank Offered Rate (LIBOR) [Member] \| TrancheB2020TermLoanTotal [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	3.00%			3.00%
London Interbank Offered Rate (LIBOR) [Member] \| 2.0 Billion Tranche B-II 2022 Term Loan [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	2.75%			2.75%
London Interbank Offered Rate (LIBOR) [Member] \| Floating Rate Senior Notes due 2018 [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	3.50%			3.50%
London Interbank Offered Rate (LIBOR) [Member] \| Level 3 Financing [Member] \| 2.0 Billion Tranche B-II 2022 Term Loan [Member]
Long-term debt
Debt Instrument, Description of Variable Rate Basis	LIBOR	LIBOR	LIBOR
London Interbank Offered Rate (LIBOR) [Member] \| Guarantor Subsidiaries [Member] \| Tranche B-III 2019, Tranche B 2020 and Tranche B 2022 Term Loans [Member]
Long-term debt
Debt Instrument, Description of Variable Rate Basis		LIBOR
Maximum [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Level 3 Financing [Member] \| Tranche B-III 2019, Tranche B 2020 and Tranche B 2022 Term Loans [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage	1.00%			1.00%
Minimum [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Level 3 Financing [Member] \| 2.0 Billion Tranche B-II 2022 Term Loan [Member]
Long-term debt
Debt Instrument, Interest Rate, Stated Percentage		0.75%