Derivatives and Hedging Activities (Details Textuals) - USD ($) shares in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2014	Dec. 31, 2015
Derivatives and Hedging Activities (Textuals) [Abstract]
Net reduction in interest expense on long term debt and other	$ 59,000,000	$ 70,000,000
Derivative asset not offset				$ 0
Shares held in equity investment sold	0.0
Margin On Interest Rate Swap Not Netted	$ 140,000,000			149,000,000
Derivative [Line Items]
Equity investment	1,000,000			1,000,000
Net hedge ineffectiveness	0	0
Derivative Instruments, Gain (Loss) Recognized in Income, Net		293,000,000
Not Sold Or Repledged [Member]
Derivative [Line Items]
Securities received as collateral	0			43,000,000
Other Expense [Member]
Derivative [Line Items]
Gain (Loss) in Changes of Fair Value of Derivatives not designated as hedges	(13,000,000)	97,000,000
Gain on embedded derivatives	6,000,000	0
ICBC [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative [Line Items]
Equity investment	0
Fair Value Hedges [Member]
Derivative [Line Items]
Notional amount of long-term debt	18,800,000,000			18,800,000,000
Net Investment Hedging [Member]
Derivative [Line Items]
Effective portion of gain (loss) on hedges	(92,000,000)	195,000,000	$ 0
Net Investment Hedging [Member] | Other Expense [Member]
Derivative [Line Items]
Amount reclassified from AOCI into income	0	0
Net hedge ineffectiveness	0	0
Net Investment Hedging [Member] | Net Investment Hedging [Member] | Other Expense [Member]
Derivative [Line Items]
Amount reclassified from AOCI into income	0	$ 0
Credit Valuation Adjustment [Member]
Derivative [Line Items]
Notional amount of long-term debt	$ (13,000,000)			$ 0