Sale of Data Centers and Colocation Business Sale of Data Centers and Colocation Business (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Sale Leaseback Transaction [Line Items]
OPERATING REVENUES	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 4,289	$ 4,382	$ 4,398	$ 4,401	$ 17,656	$ 17,470	$ 17,900
Decrease in cost of sales									(8,203)	(7,774)	(7,778)
Increase in loss on sale of business included in selling, general and administrative expense									(3,508)	(3,447)	(3,354)
Increase in depreciation expense (ongoing)									(3,936)	(3,916)	(4,189)
Increase in interest expense									(1,481)	(1,318)	(1,312)
Decrease in income tax expense									849	(394)	(438)
NET INCOME	$ 1,117	$ 92	17	$ 163	$ 42	$ 152	$ 196	$ 236	1,389	$ 626	$ 878
Cyxtera Technologies
Sale Leaseback Transaction [Line Items]
OPERATING REVENUES									49
Decrease in cost of sales									15
Increase in loss on sale of business included in selling, general and administrative expense									(102)
Increase in depreciation expense (one-time)			$ (44)						(44)
Increase in depreciation expense (ongoing)									(47)
Increase in interest expense									(39)
Decrease in income tax expense									65
NET INCOME									$ (103)