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]
Adjustments to Additional Paid in Capital [Abstract]
Additional Paid in Capital			$ 8,973
Retained Earnings (Accumulated Deficit) [Abstract]
Retained Earnings (Accumulated Deficit)				$ 12,550
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (329)					$ (329)
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition			(129)
Allocated Share-based Compensation Expense			39
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			22
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs			8
Net Income (Loss) Attributable to Parent	539			539
Dividends, Common Stock, Cash				166
Treasury Stock, Value at Dec. 31, 2015					$ (3,557)
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Treasury stock acquired					(700)
Issuance of shares under incentive and stock compensation plans from treasury stock					(130)
Return of shares under incentive and stock compensation plans and other to treasury stock					(47)
Adjustments to Additional Paid in Capital, Stock Issued, Own-share Lending Arrangement, Issuance Costs					8
Treasury Stock, Value at Jun. 30, 2016					(4,166)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax	1,229					1,229
Common Shares Outstanding, at beginning of period (in thousands) at Dec. 31, 2015		401,821.0
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Treasury stock acquired		(16,222.0)
Issuance of shares under incentive and stock compensation plans		3,203.0
Return of shares under incentive and stock compensation plans and other to treasury stock		(1,078.0)
Issuance of Shares for Warrant Exercise		192.0
Common Shares Outstanding, at end of period (in thousands) at Jun. 30, 2016		387,916.0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	254
Net Income (Loss) Attributable to Parent	216
Treasury Stock, Value at Jun. 30, 2016					(4,166)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax	646
Common Shares Outstanding, at end of period (in thousands) at Jun. 30, 2016		387,916.0
Preferred Stock, Including Additional Paid in Capital [Abstract]
Common Stock, Value, Issued		$ 5
Adjustments to Additional Paid in Capital [Abstract]
Additional Paid in Capital			8,897
Retained Earnings (Accumulated Deficit) [Abstract]
Retained Earnings (Accumulated Deficit)				12,923
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax						900
Stockholders' Equity Attributable to Parent	18,559
Common Stock, Value, Issued	4
Additional Paid in Capital	5,247		5,247
Retained Earnings (Accumulated Deficit)	13,114			13,114
Accumulated Other Comprehensive Income (Loss), Net of Tax	(337)					(337)
Stockholders' Equity Attributable to Parent	16,903
Treasury Stock, Value at Dec. 31, 2016	$ (1,125)				(1,125)
Common Shares Outstanding, at beginning of period (in thousands) at Dec. 31, 2016		373,949.0
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Treasury stock acquired	(6.7)
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition			(65)
Allocated Share-based Compensation Expense			56
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			0
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs			43
Net Income (Loss) Attributable to Parent	$ 338			338
Dividends, Common Stock, Cash				170
Treasury Stock, Value at Dec. 31, 2016	(1,125)				(1,125)
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Treasury stock acquired					(650)
Issuance of shares under incentive and stock compensation plans from treasury stock					(79)
Return of shares under incentive and stock compensation plans and other to treasury stock					(34)
Adjustments to Additional Paid in Capital, Stock Issued, Own-share Lending Arrangement, Issuance Costs					43
Treasury Stock, Value at Jun. 30, 2017	(1,687)				(1,687)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax	$ 831					831
Common Shares Outstanding, at beginning of period (in thousands) at Dec. 31, 2016		373,949.0
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Treasury stock acquired	(13.3)	(13,299.0)
Issuance of shares under incentive and stock compensation plans		1,850.0
Return of shares under incentive and stock compensation plans and other to treasury stock		(686.0)
Issuance of Shares for Warrant Exercise		1,006.0
Common Shares Outstanding, at end of period (in thousands) at Jun. 30, 2017		362,820.0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (207)
Net Income (Loss) Attributable to Parent	(40)
Treasury Stock, Value at Jun. 30, 2017	(1,687)				$ (1,687)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Net of Tax	$ 701
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Treasury stock acquired	(6.6)
Common Shares Outstanding, at end of period (in thousands) at Jun. 30, 2017		362,820.0
Preferred Stock, Including Additional Paid in Capital [Abstract]
Common Stock, Value, Issued	$ 4	$ 4
Adjustments to Additional Paid in Capital [Abstract]
Additional Paid in Capital	5,195		$ 5,195
Retained Earnings (Accumulated Deficit) [Abstract]
Retained Earnings (Accumulated Deficit)	13,282			$ 13,282
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	494					$ 494
Stockholders' Equity Attributable to Parent	$ 17,288