Revenue Recognition (Deferred Contract Acquisition and Fulfillment Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred Customer Contract Acquisition Costs Member [Member]
Capitalized Contract Cost, Net [Abstract]
Capitalized Contract Cost, Net (in millions)	$ 5,453	$ 3,974
Capitalized Contract Cost, Amortization (in millions)	2,174	1,433
Deferred Customer Contract Acquisition Costs Member [Member] \| Other Current Assets [Member]
Capitalized Contract Cost, Net [Abstract]
Capitalized Contract Cost, Net (in millions)	2,462	1,901
Deferred Customer Contract Acquisition Costs Member [Member] \| Other Assets [Member]
Capitalized Contract Cost, Net [Abstract]
Capitalized Contract Cost, Net (in millions)	2,991	2,073
Deferred Customer Contract Fulfillment Cost Member [Member]
Capitalized Contract Cost, Net [Abstract]
Capitalized Contract Cost, Net (in millions)	10,958	11,540
Capitalized Contract Cost, Amortization (in millions)	4,947	4,039
Deferred Customer Contract Fulfillment Cost Member [Member] \| Other Current Assets [Member]
Capitalized Contract Cost, Net [Abstract]
Capitalized Contract Cost, Net (in millions)	4,519	4,090
Deferred Customer Contract Fulfillment Cost Member [Member] \| Other Assets [Member]
Capitalized Contract Cost, Net [Abstract]
Capitalized Contract Cost, Net (in millions)	$ 6,439	$ 7,450