Shareholders' Equity (Shareholders' Equity, Accumulated Other Comprehensive Loss, Common Stock, and Preferred Stock) (Details) - USD ($)		Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Issued		1,071,000,000	1,071,000,000
In treasury		(215,000,000)	(223,000,000)
Total shares of common stock outstanding		856,000,000	848,000,000
Defined benefit and other postretirement liability adjustments	[1]	$ (221,000,000)	$ (326,000,000)
Cumulative translation adjustment		(78,000,000)	(70,000,000)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax		(67,000,000)	0
Other		3,000,000	(3,000,000)
Total accumulated other comprehensive loss		(363,000,000)	(399,000,000)
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock authorized to repurchase		$ 5,700,000,000
Number of shares of common stock repurchased from inception (in shares)		201,000,000
Approximate value of shares of common stock repurchased from inception		$ 8,400,000,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Number of shares of preferred stock that are authorized for issuance (in shares)		5,000,000
Number of shares preferred stock that are issued at period end (in shares)		0
Foreign Pension Plans, Defined Benefit
Class of Stock [Line Items]
Net actuarial losses		$ 205,000,000	$ 298,000,000

[1] (a) Included net actuarial losses for our international pension plans of $205 million at December 31, 2015 and $298 million at December 31, 2014.