Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance, beginning (in shares) at Dec. 31, 2017				256.1
Balance, beginning at Dec. 31, 2017	$ 26,503			$ 3	$ 8,547	$ 18,374			$ (421)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,750					3,750
Net income | Accounting Standards Update 2018-02 [Member]						91
Other comprehensive income (loss)	(474)								(474)
Other comprehensive income (loss) | Accounting Standards Update 2018-02 [Member]									(91)
Issuance of common stock under Equity Units stock purchase contracts, shares				6.0
Issuance of common stock under Equity Units stock purchase contracts	1,250				1,250
Premiums for and settlement of equity options	1				1
Repurchase and retirement of common stock, shares				(6.8)
Repurchase and retirement of common stock	(1,685)				(243)	(1,442)
Dividends and dividend equivalents	(785)					(785)
Issuance of common stock under employee stock plans, net of related tax benefits (in shares)				2.1
Issuance of common stock under employee stock plans, net of related tax benefits	318				318
Convertible debenture conversions	(337)				(337)
Balance, ending (in shares) at Dec. 31, 2018				257.4
Balance, ending at Dec. 31, 2018	28,541		$ 28,567	$ 3	9,536	19,988		$ 20,014	(986)
Balance, ending (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018		$ 26					$ 26
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,807					4,807
Other comprehensive income (loss)	$ 690								690
Repurchase and retirement of common stock, shares	(6.3)			(6.3)
Repurchase and retirement of common stock	$ (1,701)				(275)	(1,426)
Dividends and dividend equivalents	(822)					(822)
Issuance of common stock under employee stock plans, net of related tax benefits (in shares)				1.8
Issuance of common stock under employee stock plans, net of related tax benefits	396				396
Convertible debenture conversions	(209)				(209)
Balance, ending (in shares) at Dec. 31, 2019				252.9
Balance, ending at Dec. 31, 2019	31,728		$ 31,693	$ 3	9,448	22,573		$ 22,538	(296)
Balance, ending (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019		$ (35)					$ (35)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,572
Other comprehensive income (loss)	$ 446
Repurchase and retirement of common stock, shares	(9.4)			(9.4)
Repurchase and retirement of common stock	$ (2,700)				(353)	(2,347)
Dividends and dividend equivalents	(961)					(961)
Issuance of common stock under employee stock plans, net of related tax benefits (in shares)				1.9
Issuance of common stock under employee stock plans, net of related tax benefits	330				330
Convertible debenture conversions	(181)				(181)
Balance, ending (in shares) at Dec. 31, 2020				245.4
Balance, ending at Dec. 31, 2020	$ 33,199			$ 3	$ 9,244	$ 23,802			$ 150