Description of Business, Accounting Policies, and Supplemental Disclosures - Use of Estimates (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Reduction in depreciation and amortization									$ (25,251)	$ (21,789)	$ (15,341)
Increase in net income	$ 7,222	$ 6,331	$ 5,243	$ 2,535	$ 3,268	$ 2,134	$ 2,625	$ 3,561	$ 21,331	$ 11,588	$ 10,073
Increase in basic earnings per share (in dollars per share)	$ 14.38	$ 12.63	$ 10.50	$ 5.09	$ 6.58	$ 4.31	$ 5.32	$ 7.24	$ 42.64	$ 23.46	$ 20.68
Increase in diluted earnings per share (in dollars per share)	$ 14.09	$ 12.37	$ 10.30	$ 5.01	$ 6.47	$ 4.23	$ 5.22	$ 7.09	$ 41.83	$ 23.01	$ 20.14
Change in useful life of servers
Property, Plant and Equipment [Line Items]
Reduction in depreciation and amortization									$ 2,700
Increase in net income									$ 2,000
Increase in basic earnings per share (in dollars per share)									$ 4.06
Increase in diluted earnings per share (in dollars per share)									$ 3.98
Servers
Property, Plant and Equipment [Line Items]
Estimated useful lives of assets									4 years	3 years