Income Taxes - Items Accounting for Differences Between Income Taxes Computed at Federal Statutory Rate and Provision Recorded for Income Taxes (Details) - USD ($) $ 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
Income Tax Disclosure [Abstract]
Income taxes computed at the federal statutory rate									$ 5,078	$ 2,935	$ 2,365
Effect of:
Tax impact of foreign earnings and losses									(538)	453	162
State taxes, net of federal benefits									343	221	263
Tax credits									(639)	(466)	(419)
Stock-based compensation									(1,107)	(850)	(1,086)
Foreign income deduction (FDII)									(372)	(72)	(43)
2017 Impact of U.S. Tax Act									0	0	(157)
Other, net									98	153	112
Provision for income taxes, net	$ 566	$ 569	$ 984	$ 744	$ 786	$ 494	$ 257	$ 836	2,863	2,374	1,197
Excess tax benefits from stock-based compensation									$ 1,800	$ 1,400	$ 1,600