Revenue Recognition (Deferred Contract Acquisition and Fulfillment Costs) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Deferred Acquisition Costs
Capitalized Contract Cost, Net [Abstract]
Total deferred costs	$ 5,945		$ 5,453
Deferred cost amortization	1,969	$ 1,565
Deferred Acquisition Costs | Other current assets
Capitalized Contract Cost, Net [Abstract]
Total deferred costs	2,831		2,462
Deferred Acquisition Costs | Other Assets
Capitalized Contract Cost, Net [Abstract]
Total deferred costs	3,114		2,991
Deferred Fulfillment Costs
Capitalized Contract Cost, Net [Abstract]
Total deferred costs	10,015		10,958
Deferred cost amortization	3,888	$ 3,656
Deferred Fulfillment Costs | Other current assets
Capitalized Contract Cost, Net [Abstract]
Total deferred costs	4,234		4,519
Deferred Fulfillment Costs | Other Assets
Capitalized Contract Cost, Net [Abstract]
Total deferred costs	$ 5,781		$ 6,439