CONSOLIDATED STATEMENTS OF STOCKHOLDER'S EQUITY (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ACCUMULATED DEFICIT
Cumulative net effect of adoption of ASU 2014-09, tax	$ (49)	$ 0	$ 0

Cumulative Effect of New Accounting Principle in Period of Adoption, Tax

No definition available.

Name:	ctl_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoptionTax
Namespace Prefix:	ctl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant