Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity	$ 7,679	$ 566	$ 4,445		$ 2,807	$ (139)
Additional Paid-in Capital				$ 0
Balance (in shares) at Dec. 31, 2017			197,532
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	238				238
Other comprehensive income, net of tax	(128)					(128)
Preferred Stock Redemption	1				1
Stock Issued During Period, Value, Conversion of Convertible Securities
Stock Repurchased and Retired During Period, Value	115
Common Stock Repurchased, Accumulated Paid-in Capital	$ (122)		$ (122)
Net Shares Issued From Stock Warrant Exercises			1,042
Company Common Stock Repurchased, Shares	2,200		(2,277)
Net activity under employee plans and related tax benefits	$ 23		$ 23
Net activity under employee plans and related tax benefits, shares			753
Dividends on preferred stock	(7)				(7)
Dividends on common stock	(40)				(40)
Balance (in shares) at Mar. 31, 2018			197,050
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity	7,644	566	$ 4,346		2,999	(267)
Additional Paid-in Capital				0
Stockholders' Equity	7,578	566	$ 0		3,456	(250)
Additional Paid-in Capital	$ 3,806			3,806
Balance (in shares) at Dec. 31, 2018	187,554		187,554
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	$ 213				213
Other comprehensive income, net of tax	128					128
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(3)				(3)
Stock Repurchased and Retired During Period, Value	275
Common Stock Repurchased, Accumulated Paid-in Capital	(276)			(276)
Net Shares Issued From Stock Warrant Exercises			1
Stock Issued During Period, Value, Stock Options Exercised
Company Common Stock Repurchased, Shares	5,500		(5,506)
Net activity under employee plans and related tax benefits	$ 11
Employee Plans, Accumulated Paid-in Capital				11
Net activity under employee plans and related tax benefits, shares			464
Dividends on preferred stock	(7)				(7)
Dividends on common stock	$ (56)				(56)
Balance (in shares) at Mar. 31, 2019	182,513		182,513
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity	$ 7,588	$ 566	$ 0		$ 3,603	$ (122)
Additional Paid-in Capital	$ 3,541			$ 3,541