Revenue Recognition - Disaggregation of Revenue by Geography (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue by Geography
Revenues	$ 17,560	$ 18,028	$ 53,253	$ 55,370	$ 77,000
Americas
Revenue by Geography
Revenues	8,139	8,514	24,755	25,813
EMEA
Revenue by Geography
Revenues	5,564	5,477	16,775	17,354
Asia Pacific
Revenue by Geography
Revenues	$ 3,857	$ 4,036	$ 11,723	$ 12,203