Basis of Presentation - Reclassification (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenues		$ 17,571	$ 18,182	$ 77,000
Cost of Revenue		9,649	10,139
Services
Revenues	[1]	11,373	11,915
Cost of Revenue	[1]	7,843	8,272
Sales
Revenues	[1]	5,895	5,862
Cost of Revenue	[1]	$ 1,624	1,603
Adjustment
Revenues				$ 300
Adjustment | Services
Revenues			(500)
Cost of Revenue			(100)
Adjustment | Sales
Revenues			500
Cost of Revenue			$ 100

[1] Reclassified to conform to current period presentation. Refer to note 1, “Basis of Presentation,” for additional information.