Sale of Data Centers and Colocation Business - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended		4 Months Ended	8 Months Ended	12 Months Ended			16 Months Ended
	May 01, 2017	Jun. 30, 2017	Mar. 31, 2017	May 01, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 01, 2017
Cyxtera Technologies
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Due to affiliate, current						$ 3
Current amount due from affiliate					$ 49	10	$ 49
Payments for rent						132
Sale-leaseback transaction rent expense					$ 80
Cyxtera Technologies
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on asset leaseback, failed-sale-leaseback transaction		$ (119)				(102)
Sale and leaseback transaction loss, net						(82)
SIS Holdings, LP
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling interest in limited partnerships	$ 150			$ 150		150			$ 150
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 colocation business and data centers	$ 1,800
Tax effect of gain (loss) from disposal of discontinued operation							$ 47	$ 18	$ 65
Depreciation and amortization			$ 50	$ 67
Colocation Business and Data Centers | Cyxtera Technologies | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal group, gain (loss) on disposal						$ 20