Description of Business and Accounting Policies - Use of Estimates (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								12 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Operating income		$ 3,879	$ 3,157	$ 3,084	$ 4,420	$ 3,786	$ 3,724	$ 2,983	$ 1,927	$ 14,541	$ 12,421	$ 4,106
Servers
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets										3 years
Subsequent Event | Servers
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets	4 years
Forecast
Property, Plant and Equipment [Line Items]
Operating income	$ 2,300