Derivatives and Hedging Activities (Details Textuals) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Derivatives and Hedging Activities (Textuals) [Abstract]
Net reduction in interest expense on long term debt and other	$ (13)	$ 37	$ 1	$ 81
Margin On Interest Rate Swap Not Netted	118		118		$ 146
Derivative [Line Items]
Notional amount of long-term debt	23,200		23,200		23,600
Gross amount of hedged item	23,700		23,700		23,800
Cummulative fair value hedging adjustment of hedged item in fair value hedge	(451)		(451)		$ (182)
Other Expense [Member]
Derivative [Line Items]
Gain (Loss) in Changes of Fair Value of Derivatives not designated as hedges	55	(4)	34	(21)
Gain on embedded derivatives	(4)	(3)	(6)	(2)
Net Investment Hedges [Member]
Derivative [Line Items]
Effective portion of gain (loss) on hedges	$ 320	$ (102)	158	(331)
Net Investment Hedges [Member] | Other Expense [Member]
Derivative [Line Items]
Amount reclassified from AOCI into income			1	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			$ 1	$ 0