Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Capital Surplus	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
BALANCE (in shares)		175.3
Cumulative effect of change in accounting principle(s)	$ 1		$ 3		$ (2)
BALANCE at Dec. 31, 2016	7,796	$ 1,141	2,135	$ (383)	7,331	$ (2,428)
Net income	743				743
Other comprehensive income (loss), net of tax	19			19
Cash dividends declared on common stock	(193)				(193)
Purchase of common stock	(544)					544
Purchase of common stock (in shares)		(7.5)
Net issuance of common stock under employee stock plans	102		(24)		(26)	152
Net issuance of common stock under employee stock plans (in shares)		3.3
Net issuance of common stock for warrants	0		(30)		(53)	83
Net issuance of common stock for warrants (in shares)		1.8
Share-based compensation	39		39
Reclassification of certain deferred tax effects	0			(87)	87
Other	0		(1)			1
BALANCE at Dec. 31, 2017	7,963	$ 1,141	2,122	(451)	7,887	(2,736)
BALANCE (in shares)		172.9
Cumulative effect of change in accounting principle(s)	15		0	1	14
Net income	1,235				1,235
Other comprehensive income (loss), net of tax	(159)			(159)
Cash dividends declared on common stock	(309)				(309)
Purchase of common stock	(1,329)		3			1,326
Purchase of common stock (in shares)		(14.9)
Net issuance of common stock under employee stock plans	43		(9)		(23)	75
Net issuance of common stock under employee stock plans (in shares)		1.5
Net issuance of common stock for warrants	0		(10)		(23)	33
Net issuance of common stock for warrants (in shares)		0.6
Share-based compensation	48		48
BALANCE at Dec. 31, 2018	7,507	$ 1,141	2,148	(609)	8,781	(3,954)
BALANCE (in shares)		160.1
Cumulative effect of change in accounting principle(s)	(14)			0	(14)
Net income	1,198				1,198
Other comprehensive income (loss), net of tax	374			374
Cash dividends declared on common stock	(398)				(398)
Purchase of common stock	(1,380)		0			1,380
Purchase of common stock (in shares)		(18.7)
Net issuance of common stock under employee stock plans	1		(13)		(29)	43
Net issuance of common stock under employee stock plans (in shares)		0.7
Share-based compensation	39		39
BALANCE at Dec. 31, 2019	$ 7,327	$ 1,141	$ 2,174	$ (235)	$ 9,538	$ (5,291)
BALANCE (in shares)		142.1