CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (PARENTHETICAL) - RETAINED EARNINGS (ACCUMULATED DEFICIT) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounting Standards Update 2016-02
Cumulative net effect of adoption of ASU, tax	$ (37)
Accounting Standards Update 2014-09
Cumulative net effect of adoption of ASU, tax	$ 119	$ (119)

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