Taxation (Provision For Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Examination [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ 527	$ 766	$ 469
Income (Loss) from Continuing Operations before Income Taxes, Foreign	3,195	4,184	2,827
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	3,722	4,950	3,296
Current tax expense	359	824	304
Deferred tax expense	(498)	(9)	158
Provision for income taxes	(139)	815	462
Domestic Tax Authority [Member]
Income Tax Examination [Line Items]
Current tax expense	46	97	38
Deferred tax expense	2	(27)	4
Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Current tax expense	313	727	266
Deferred tax expense	$ (500)	$ 18	$ 154