Derivatives and Hedging Activities (Details Textuals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Derivatives And Hedging Activities Textuals [Abstract]
Net reduction in interest expense	$ 32	$ 47	$ 100	$ 133
Derivative [Line Items]
Ineffectiveness reclassified from AOCI into income	0	0	0	0
Margin on interest rate swap not netted	124		124		$ 128
Derivative Instruments, Gain (Loss) Recognized in Income, Net		12		291	293	$ 587
Fair Value Hedging [Member]
Derivative [Line Items]
Notional amount of long-term debt	14,100		14,100		15,900
Net Investment Hedging [Member]
Derivative [Line Items]
Effection portion of gain (loss) on hedges	(29)	188	(28)	274
Credit Valuation Adjustment [Member]
Derivative [Line Items]
Notional amount of long-term debt	0		0		0
Other expense [Member]
Derivative [Line Items]
Gain (Loss) in Changes of Fair Value of Derivatives not designated as hedges	3	$ (6)	1	$ 22
Risk Exposure Low [Member]
Offsetting Assets [Line Items]
Total derivatives assets,net	0		0		0
Individually Significant Counterparties [Member]
Offsetting Assets [Line Items]
Total derivatives assets,net	$ 0		$ 0		$ 0