Intangible Assets - Schedule of Intangible Assets by Class (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 20,696	$ 21,036
Accumulated Amortization	5,338	3,394
Net Book Value	15,358	17,642
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	15,271	16,187
Accumulated Amortization	3,668	2,145
Net Book Value	11,603	14,042
Acquired software and technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,562	2,607
Accumulated Amortization	879	639
Net Book Value	1,683	1,968
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	618	620
Accumulated Amortization	172	105
Net Book Value	446	515
Purchased software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	913	680
Accumulated Amortization	207	173
Net Book Value	706	507
Capitalized software and other intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,332	942
Accumulated Amortization	412	332
Net Book Value	920	610
Gross software development costs capitalized	$ 462	$ 339	$ 193