The duration in years of a contract or agreement.

No definition available.

Name:	ctl_ContractorAgreementTerm
Namespace Prefix:	ctl_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of federal funding per agreement that is expected to be received over a prescribed period of time.

+ References

No definition available.

+ Details

Name:	ctl_FederalSupportTotalAmountperAgreement
Namespace Prefix:	ctl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the number of rural households and businesses served by the entity.

+ References

No definition available.

+ Details

Name:	ctl_NumberofRuralHouseholdsandBusinesses
Namespace Prefix:	ctl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Revenues received during the transition from one source of revenue to a replacement source of revenue, the purpose of which is to adjust previously recorded revenues to the amount that would have been recorded had revenues been received from the replacement source at the beginning of the period.

+ References

No definition available.

+ Details

Name:	ctl_OtherOperatingRevenuesTransitionalRevenues
Namespace Prefix:	ctl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_EntityWideInformationRevenueFromExternalCustomerLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ProductOrServiceAxis=ctl_CAFPhase2SupportMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Basis of Presentation (Details) - CAF Phase 2 Support number in Millions, $ in Millions		3 Months Ended	6 Months Ended
	Aug. 27, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2016 state
Operating revenues by products and services
Federal support, total amount per agreement	$ 500
Contract or agreement term	6 years
Number of rural households and businesses	1.2
Number of states in which service is provided (states) \| state				33
Transitional payment		$ 127	$ 112