Derivatives (Hedges of Net Investments in Foreign Operations) (Details) - Foreign Operations Hedges [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in AOCI (Effective Portion)	$ 81	$ (33)	$ (76)	$ (359)
Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in AOCI (Effective Portion)	43	(31)	35	(126)
Currency options
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in AOCI (Effective Portion)	$ 38	$ (2)	$ (111)	$ (233)