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]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity	$ 7,634	$ 710	$ 4,725	$ 2,321	$ (122)
Additional Paid-in Capital			$ 0
Balance (in shares) at Dec. 31, 2016			203,085
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	469			469
Other comprehensive income, net of tax	65				65
Preferred Stock Redemption	(144)	(144)	$ 2	(2)
Stock Issued During Period, Value, Conversion of Convertible Securities
Stock Repurchased and Retired During Period, Value	(217)		$ (217)
Company Common Stock Repurchased, Shares			(4,975)
Net activity under employee plans and related tax benefits	42		$ 42
Net activity under employee plans and related tax benefits, shares			1,602
Dividends on preferred stock	(30)			(30)
Dividends on common stock	(58)			(58)
Balance (in shares) at Sep. 30, 2017			199,712
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity	7,761	566	$ 4,552	2,700	(57)
Additional Paid-in Capital			0
Stockholders' Equity	7,679	566	4,445	2,807	(139)
Additional Paid-in Capital	$ 0			0
Common Stock, Adjustments			(4,052)
Adjustments to Additional Paid in Capital, Other			$ 4,052
Balance (in shares) at Dec. 31, 2017	197,532		197,532
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	$ 658			658
Other comprehensive income, net of tax	(222)				(222)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	1			1
Stock Repurchased and Retired During Period, Value	(434)		$ (434)
Net Shares Issued From Stock Warrant Exercises			1,278
Stock Issued During Period, Value, Stock Options Exercised
Company Common Stock Repurchased, Shares	8,000		(8,050)
Net activity under employee plans and related tax benefits	$ 41		$ 41
Net activity under employee plans and related tax benefits, shares			1,409
Dividends on preferred stock	(25)			(25)
Dividends on common stock	$ (145)			(145)
Balance (in shares) at Sep. 30, 2018	192,169		192,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity	$ 7,553	$ 566	$ 0	$ 3,296	$ (361)
Additional Paid-in Capital	$ 4,052		$ 4,052