Consolidated Statements Of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Balance at Dec. 31, 2016	$ 25,100	$ 3	$ 8,805	$ 16,560	$ (268)
Balance (in shares) at Dec. 31, 2016		263.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,612			2,612
Other comprehensive income (loss)	142				142
Premiums for and settlement of equity options	1		1
Repurchase and retirement of common stock, value	$ (1,635)	$ 0	(296)	(1,339)
Repurchase and retirement of common stock, shares	(8.7)	(8.7)
Dividends and dividend equivalents	$ (527)			(527)
Issuance of common stock under employee stock plans, net of related tax benefits	256		256
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		2.4
Convertible debenture repurchases and conversions	(1)		(1)
Balance at Sep. 30, 2017	25,948	$ 3	8,765	17,306	(126)
Balance (in shares) at Sep. 30, 2017		257.4
Adoption of ASU 2016-01				320	(320)
Adjusted balance January 1, 2018	26,503		8,547	18,374	(421)
Balance at Dec. 31, 2017	26,503	$ 3	8,547	18,054	(101)
Balance (in shares) at Dec. 31, 2017		256.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,325			3,325
Other comprehensive income (loss)	$ (299)				(299)
Issuance of common stock under Equity Units stock purchase contracts, shares	6.0	6.0
Issuance of common stock under Equity Units stock purchase contracts	$ 1,250		1,250
Repurchase and retirement of common stock, value	$ (1,192)	$ 0	(174)	(1,018)
Repurchase and retirement of common stock, shares	(5.0)	(5.0)
Dividends and dividend equivalents	$ (590)			(590)
Issuance of common stock under employee stock plans, net of related tax benefits	192		192
Issuance of common stock under employee stock plans, net of related tax benefits, Shares		1.8
Convertible debenture repurchases and conversions	(95)		(95)
Adoption of ASU 2018-02 (Note 2)	91			91	(91)
Balance at Sep. 30, 2018	$ 29,094	$ 3	$ 9,720	$ 20,182	$ (811)
Balance (in shares) at Sep. 30, 2018		258.9