Derivatives and Hedging Activities (Details Textuals) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivatives And Hedging Activities Textuals [Abstract]
Net reduction in interest expense	$ 34	$ 44	$ 68	$ 86
Derivative [Line Items]
Ineffectiveness reclassified from AOCI into income	0	0	0	0
Margin on interest rate swap not netted	139		139		$ 128
Derivative Instruments, Gain (Loss) Recognized in Income, Net		21		279
Fair Value Hedging [Member]
Derivative [Line Items]
Notional amount of long-term debt	17,400		17,400		15,900
Net Investment Hedging [Member]
Derivative [Line Items]
Effection portion of gain on hedges	51	22	1	85
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	(1)	$ 15	(2)	$ 29
None Sold or Repledged [Member]
Offsetting Assets [Line Items]
Securities received as collateral	0		0		0
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