Derivatives and Hedging Activities (Details Textuals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivatives And Hedging Activities Textuals [Abstract]
Net reduction in interest expense on long term debt	$ 8	$ 32	$ 47	$ 100
Derivative [Line Items]
Margin on interest rate swap not netted	135		135		$ 144
Derivative Instruments, Gain (Loss) [Line Items]
Net hedge ineffectiveness	0	0	0	0
Fair Value Hedging [Member]
Derivative [Line Items]
Notional amount of long-term debt	16,200		16,200		$ 14,800
Net Investment Hedging [Member]
Derivative [Line Items]
Effective portion of loss (gain) on hedges	95	29	263	28
Ineffectiveness reclassified from AOCI into income	0	0	0	0
Other expense [Member]
Derivative [Line Items]
Loss (gain) in Changes of Fair Value of Derivatives not designated as hedges	(8)	$ (3)	(19)	$ (1)
Interest Rate Contract [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative [Line Items]
Derivative Liability	87		87
Derivative Assets, Cleared Collateral, Offset	1		1
Derivative Liabilities, Cleared Collateral, Offset	79		79
Total derivatives assets	$ 1		$ 1