Derivatives (Hedges of Net Investments in Foreign Operations) (Details) - Foreign Operations Hedges [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in AOCI	$ (125)	$ (445)	$ (302)
Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in AOCI	35	(155)	(267)
Currency options
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gains (Losses) Deferred in AOCI	$ (160)	$ (290)	$ (35)