Taxation (Provision For Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Current tax expense	$ 304	$ 481	$ 231
Deferred tax expense	158	153	249
Provision for income taxes	$ 462	$ 634	$ 480