Shareholders' Equity (Shareholders' Equity, Accumulated Other Comprehensive Loss, Common Stock, and Preferred Stock) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Stock Repurchased During Period, Shares		10,500,000	0
Treasury Stock, Value, Acquired, Cost Method		$ 400,000,000
Issued		1,069,000,000	1,069,000,000
In treasury		(198,000,000)	(196,000,000)
Total shares of common stock outstanding		871,000,000	873,000,000
Defined benefit and other postretirement liability adjustments	[1]	$ (203,000,000)	$ (334,000,000)
Cumulative translation adjustment		(82,000,000)	(80,000,000)
Other		(70,000,000)	(55,000,000)
Total accumulated other comprehensive loss		(355,000,000)	(469,000,000)
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stock authorized to repurchase		$ 5,300,000,000
Number of shares of common stock repurchased from inception (in shares)		212,000,000
Approximate value of shares of common stock repurchased from inception		$ 8,800,000,000
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 Plan [Member]
Class of Stock [Line Items]
Net actuarial losses		$ 184,000,000	$ 295,000,000

[1] Included net actuarial losses for our international pension plans of $184 million at December 31, 2018 and $295 million at December 31, 2017.