Accounting Policies and Supplemental Disclosures - Use of Estimates (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Property, Plant and Equipment [Line Items]
Decrease in depreciation and amortization	$ (5,748)	$ (5,202)	$ (11,110)	$ (10,056)	$ (22,843)		$ (18,097)
Increase in net income	$ 5,243	$ 2,625	$ 7,778	$ 6,186	$ 13,180		$ 12,096
Increase in basic earnings per share	$ 10.50	$ 5.32	$ 15.59	$ 12.57
Increase in diluted earnings per share	$ 10.30	$ 5.22	$ 15.32	$ 12.31
Technology equipment
Property, Plant and Equipment [Line Items]
Useful life of equipment			4 years			3 years
Change in equipment useful life
Property, Plant and Equipment [Line Items]
Decrease in depreciation and amortization	$ 696		$ 1,500
Increase in net income	$ 534		$ 1,100
Increase in basic earnings per share	$ 1.07		$ 2.27
Increase in diluted earnings per share	$ 1.05		$ 2.24