Sale of Data Centers and Colocation Business - Effects of Failed-sale-Leaseback (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Sale Leaseback Transaction [Line Items]
Operating revenue	$ 5,570	$ 5,606	$ 5,578	$ 5,647	$ 5,778	$ 5,818	$ 5,902	$ 5,945	$ 22,401	$ 23,443	$ 17,656
Increase in loss on sale of business included in selling, general and administrative expense									(3,715)	(4,165)	(3,508)
Increase in depreciation expense (ongoing)									(4,829)	(5,120)	(3,936)
Increase in interest expense									(2,021)	(2,177)	(1,481)
Decrease in income tax expense									(503)	(170)	849
NET (LOSS) INCOME	$ 223	$ 302	$ 371	$ (6,165)	$ (2,412)	$ 272	$ 292	$ 115	$ (5,269)	(1,733)	1,389
Cyxtera Technologies
Sale Leaseback Transaction [Line Items]
Operating revenue										74	49
Decrease in cost of sales										22	15
Increase in loss on sale of business included in selling, general and administrative expense										0	(102)
Increase in depreciation expense (one-time)										0	(44)
Increase in depreciation expense (ongoing)										(69)	(47)
Increase in interest expense										(55)	(39)
Decrease in income tax expense										7	65
NET (LOSS) INCOME										$ (21)	$ (103)