Sale of Data Centers and Colocation Business (Details) - USD ($) $ in Millions	May 01, 2017	Mar. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total net amount of assets derecognized		$ 140	$ 140
Colocation Business and Data Centers
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sales of data centers and colocation business	$ 1,800
Colocation Business and Data Centers | Disposal group disposed of by sale, not discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill	1,142
Property, plant and equipment	1,051
Other intangible assets	249
Other assets	66
Total net amount of assets derecognized	1,982
Capital lease obligations	294
Other liabilities	274
Total net imputed liabilities recognized	(60)
SIS Holdings, LP | CenturyLink, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
CenturyLink, Inc.'s value of minority stake		$ 150
Cyxtera Technologies
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Less assets recorded as part of the failed-sale-leaseback	(526)
Less imputed financing obligations from the failed-sale-leaseback	$ (628)