Condensed Consolidated Statements of Changes in Stockholders' Equity Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stocks	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Stockholders' Equity, Total [Member]
Adjustments to Additional Paid in Capital [Abstract]
Additional Paid in Capital			$ 9,123
Retained Earnings (Accumulated Deficit) [Abstract]
Retained Earnings (Accumulated Deficit)				$ 11,191
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax						$ 928
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition			(150)
Allocated Share-based Compensation Expense			16
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			26
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs			19
Net Income (Loss) Attributable to Parent	$ 467			467
Dividends, Common Stock, Cash				75
Treasury Stock, Value at Dec. 31, 2014					$ (2,527)
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Treasury stock acquired					(250)
Issuance of shares under incentive and stock compensation plans from treasury stock					(154)
Return of shares under incentive and stock compensation plans and other to treasury stock	(25)				(53)
Adjustments to Additional Paid in Capital, Stock Issued, Own-share Lending Arrangement, Issuance Costs					19
Treasury Stock, Value at Mar. 31, 2015					(2,657)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax	222					222
Common Shares Outstanding, at beginning of period (in thousands) at Dec. 31, 2014		424,416.0
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Treasury stock acquired		(6,128.0)
Issuance of shares under incentive and stock compensation plans		3,923.0
Return of shares under incentive and stock compensation plans and other to treasury stock		(1,299.0)
Issuance of Shares for Warrant Exercise		477.0
Common Shares Outstanding, at end of period (in thousands) at Mar. 31, 2015		421,389.0
Adjustments to Additional Paid in Capital [Abstract]
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			0
Treasury Stock, Value at Dec. 31, 2014					(2,527)
Treasury Stock, Value at Dec. 31, 2015	(3,557)				(3,557)
Common Shares Outstanding, at beginning of period (in thousands) at Dec. 31, 2014		424,416.0
Common Shares Outstanding, at end of period (in thousands) at Dec. 31, 2015		401,821.0
Preferred Stock, Including Additional Paid in Capital [Abstract]
Common Stock, Value, Issued		$ 5
Adjustments to Additional Paid in Capital [Abstract]
Additional Paid in Capital			8,996
Retained Earnings (Accumulated Deficit) [Abstract]
Retained Earnings (Accumulated Deficit)				11,583
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax						1,150
Total stockholders' equity							$ 19,077
Common Stock, Value, Issued	5
Additional Paid in Capital	8,973		8,973
Retained Earnings (Accumulated Deficit)	12,550			12,550
Accumulated Other Comprehensive Income (Loss), Net of Tax	(329)					(329)
Total stockholders' equity	17,642
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition			(124)
Allocated Share-based Compensation Expense			19
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			24
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs			7
Net Income (Loss) Attributable to Parent	323			323
Dividends, Common Stock, Cash				84
Treasury stock acquired					(350)
Issuance of shares under incentive and stock compensation plans from treasury stock					(125)
Return of shares under incentive and stock compensation plans and other to treasury stock	(10)				(46)
Adjustments to Additional Paid in Capital, Stock Issued, Own-share Lending Arrangement, Issuance Costs					7
Treasury Stock, Value at Mar. 31, 2016	(3,821)				$ (3,821)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax	$ 583					583
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Treasury stock acquired	(8.4)	(8,394.0)
Issuance of shares under incentive and stock compensation plans		3,069.0
Return of shares under incentive and stock compensation plans and other to treasury stock		(1,066.0)
Issuance of Shares for Warrant Exercise		173.0
Common Shares Outstanding, at end of period (in thousands) at Mar. 31, 2016		395,603.0
Preferred Stock, Including Additional Paid in Capital [Abstract]
Common Stock, Value, Issued	$ 5	$ 5
Adjustments to Additional Paid in Capital [Abstract]
Additional Paid in Capital	8,885		$ 8,885
Retained Earnings (Accumulated Deficit) [Abstract]
Retained Earnings (Accumulated Deficit)	12,789			$ 12,789
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	254					$ 254
Total stockholders' equity	$ 18,112						$ 18,112