Derivatives and Hedging Activities (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives and Hedging Activities (Textuals) [Abstract]
Net reduction in interest expense on long term debt and other	$ 133	$ 224	$ 284
Margin on interest rate swap not netted	146	169
Derivative [Line Items]
Equity investment	48	49
Total derivatives assets, net	124	555
Other Expense [Member]
Derivative [Line Items]
Gain (Loss) in changes of Fair Value of Derivatives not designated as hedges	(29)	1	83
Gain on embedded derivatives	0	9	5
Fair Value Hedges [Member]
Derivative [Line Items]
Notional amount of long-term debt	23,800	17,700
Cash Flow Hedges [Member]
Derivative [Line Items]
Notional amount of long-term debt		0
Net Investment Hedges [Member]
Derivative [Line Items]
Effective portion of gain (loss) on hedges	(370)	281	577
Net Investment Hedges [Member] | Other Expense [Member]
Derivative [Line Items]
Amount Of Ineffectiveness On Net Investment Hedges	0	0	1
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(31)	(5)	$ 0
Credit Valuation Adjustment [Member]
Derivative [Line Items]
Notional amount of long-term debt	0	0
Not Sold Or Repledged [Member]
Derivative [Line Items]
Securities received as collateral	0	18
Risk Exposure Low [Member]
Derivative [Line Items]
Total derivatives assets, net	0	537
Significant Counterparties [Member]
Derivative [Line Items]
Total derivatives assets, net	0	$ 0
Total derivatives liabilities, net	$ 0