Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Capital Surplus	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock
BALANCE (in shares) at Dec. 31, 2018			160.1
BALANCE at Dec. 31, 2018	$ 7,507		$ 1,141	$ 2,148	$ (609)	$ 8,781	$ (3,954)
Net income	637					637
Other comprehensive income (loss), net of tax	227				227
Cash dividends declared on common stock	(205)					(205)
Purchase of common stock	859			0			859
Purchase of common stock (in shares)			(10.9)
Issuance of preferred stock	0
Net issuance of common stock under employee stock plans	2			12		23	33
Net issuance of common stock under employee stock plans (in shares)			0.6
Share-based compensation	32			32
BALANCE at Jun. 30, 2019	7,323		$ 1,141	2,168	(382)	9,176	(4,780)
BALANCE (in shares) at Jun. 30, 2019			149.8
BALANCE (in shares) at Mar. 31, 2019			155.4
BALANCE at Mar. 31, 2019	7,409		$ 1,141	2,159	(513)	8,979	(4,357)
Net income	298					298
Other comprehensive income (loss), net of tax	131				131
Cash dividends declared on common stock	(100)					(100)
Purchase of common stock	425						425
Purchase of common stock (in shares)			(5.7)
Net issuance of common stock under employee stock plans	2			1		1	2
Net issuance of common stock under employee stock plans (in shares)			0.1
Share-based compensation	8			8
BALANCE at Jun. 30, 2019	7,323		$ 1,141	2,168	(382)	9,176	(4,780)
BALANCE (in shares) at Jun. 30, 2019			149.8
BALANCE (in shares) at Dec. 31, 2019			142.1
BALANCE at Dec. 31, 2019	7,327		$ 1,141	2,174	(235)	9,538	(5,291)
Net income	48					48
Other comprehensive income (loss), net of tax	393				393
Cash dividends declared on common stock	(192)					(192)
Purchase of common stock	194			0			194
Purchase of common stock (in shares)			(3.4)
Issuance of preferred stock	395	$ 395
Net issuance of common stock under employee stock plans	0			13		3	16
Net issuance of common stock under employee stock plans (in shares)			0.3
Share-based compensation	12			12
BALANCE at Jun. 30, 2020	7,802	395	$ 1,141	2,173	158	9,404	(5,469)
BALANCE (in shares) at Jun. 30, 2020			139.0
BALANCE (in shares) at Mar. 31, 2020			139.0
BALANCE at Mar. 31, 2020	7,402		$ 1,141	2,168	174	9,389	(5,470)
Net income	113					113
Other comprehensive income (loss), net of tax	(16)				(16)
Cash dividends declared on common stock	(98)					(98)
Purchase of common stock	1						1
Issuance of preferred stock	395	395
Net issuance of common stock under employee stock plans	1			1
Share-based compensation	4			4
BALANCE at Jun. 30, 2020	$ 7,802	$ 395	$ 1,141	$ 2,173	$ 158	$ 9,404	$ (5,469)
BALANCE (in shares) at Jun. 30, 2020			139.0