Shareholders' Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Balance		$ 13,521	$ 13,951	$ 13,886	$ 15,770
Net current-period other comprehensive loss		(257)	(101)	(377)	(294)
Balance		13,134	13,978	13,134	13,978
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	[1]	(786)	(693)	(714)	(529)
Other comprehensive loss	[1],[2]	(235)	(128)	(293)	(281)
Equity method affiliates	[1],[3]	(3)		(17)	(11)
Net current-period other comprehensive loss	[1]	(238)	(128)	(310)	(292)
Balance	[1]	(1,024)	$ (821)	(1,024)	(821)
Other Comprehensive Income, Tax		$ 16		$ 39	$ 28

[1] All amounts are after tax. Amounts in parentheses indicate debits to accumulated other comprehensive loss.

[2] For the three and nine months ended September 30, 2019, amounts are net of tax benefit of $16 million and $39 million, respectively. For the three months ended September 30, 2018, tax amount is not significant. For the nine months ended September 30, 2018, amount is net of tax benefit of $28 million.

[3] Tax effects are not significant.