Products and Services Revenues - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) category	Sep. 30, 2017 USD ($)
Revenue from Contract with Customer [Abstract]
Number of categories of products and services \| category			6
Universal service funds taxes and surcharges \| $	$ 28	$ 33	$ 93	$ 100

Represents the taxes and surcharges on revenues from universal service funds (USF), which are included in operating revenues and expenses.

No definition available.

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