Provision for Income Taxes (Schedule of Current and Deferred Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Current U.S. federal tax expense, on continuing operations	$ 40	$ 218	$ 656
Current U.S. state and local tax expense, on continuing operations	11	7	38
Current international tax expense, on continuing operations	592	466	449
Total current tax expense, on continuing operations	643	691	1,143
Deferred U.S. federal tax expense, on continuing operations	27	139	91
Deferred U.S. state and local tax (benefit) expense, on continuing operations	(29)	4	(42)
Deferred international tax expense (benefit), on continuing operations	103	(138)	(24)
Total deferred tax expense, on continuing operations	101	5	25
Provision for income taxes on continuing operations	$ 744	$ 696	$ 1,168