CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (PARENTHETICAL) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
RETAINED EARNINGS (ACCUMULATED DEFICIT) \| Accounting Standards Update 2014-09
Cumulative net effect of adoption of ASU, tax	$ (119)	$ 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