CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Millions	Dec. 31, 2017 USD ($)
RETAINED EARNINGS \| Accounting Standards Update 2014-09
Cumulative net effect of adoption, tax	$ 101

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