Derivatives and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative asset not offset	$ 0	$ 0
Derivative liabilities not offset	0	0
Individually Significant Counterparties [Member]
Derivatives, Fair Value [Line Items]
Total derivatives, net	0	0
Not Sold Or Repledged [Member]
Derivatives, Fair Value [Line Items]
Securities received as collateral	0	335
Risk Exposure Low [Member]
Derivatives, Fair Value [Line Items]
Total derivatives, net	403	258
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	958	942
Cash collateral netting	(524)	(326)
Derivative asset and liability netting	(31)	(23)
Total derivatives, net	403	593
Other Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	803	867
Other Assets [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	155	75
Other Assets [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	0	0
Other Assets [Member] | Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	155	75
Other Assets [Member] | Equity-linked contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	0	0
Other Assets [Member] | Fair Value Hedging [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	718	824
Other Assets [Member] | Fair Value Hedging [Member] | Total Return Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	4	0
Other Assets [Member] | Net Investment Hedging [Member] | Foreign exchange contracts [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives assets	81	43
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	230	329
Cash collateral netting	0	(21)
Derivative asset and liability netting	(31)	(23)
Total derivatives, net	199	285
Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	153	169
Other Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	77	160
Other Liabilities [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	0	0
Other Liabilities [Member] | Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	76	158
Other Liabilities [Member] | Equity-linked contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	1	2
Other Liabilities [Member] | Fair Value Hedging [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	0	0
Other Liabilities [Member] | Fair Value Hedging [Member] | Total Return Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	0	19
Other Liabilities [Member] | Net Investment Hedging [Member] | Foreign exchange contracts [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Total fair value of derivatives liabilties	$ 153	$ 150