Derivative Instruments and Hedging Activities (Fair Value Amounts of Derivative Instruments Reported on our Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 80	$ 95
Derivative Liability, Fair Value, Gross Liability	81	95
Derivative, Notional Amount	31,090	34,166
Interest Receivable	457	476
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	18	20
Derivative Liability, Fair Value, Gross Liability	18	21
Derivative, Notional Amount	4,089	4,902
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	18	19
Derivative Liability, Fair Value, Gross Liability	17	21
Derivative, Notional Amount	3,939	4,731
Hedge notional amount associated with debt maturing in five or more years	2,600
Foreign Exchange Forward [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	150	171
Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	62	73
Derivative Liability, Fair Value, Gross Liability	62	73
Derivative, Notional Amount	26,907	29,172
Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	94	92
Equity Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	0	1
Derivative, Notional Amount	0	0
Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Receive-fixed Swaps, Fair Value, Gross Asset	11	8
Receive-fixed Swaps, Fair Value, Gross Liability	18	14
Receive-fixed Swaps, Notional Amount	2,600	1,700
Pay-fixed Swaps, Fair Value, Gross Asset	7	10
Pay-fixed Swaps, Fair Value, Gross Liability	0	1
Pay-fixed Swaps, Notional Amount	1,400	2,800
Interest Rate Swap [Member] \| Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	43	137
Foreign Exchange Forward [Member] \| Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	94	92
Futures and Forwards [Member] \| Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	25	0
Written Options [Member] \| Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	62	73
Derivative, Notional Amount	13,432	14,518
Written Options [Member] \| Equity Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	1
Derivative, Notional Amount	0	0
Purchased Options [Member] \| Interest Rate Contract [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	62	73
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	13,407	14,517
Purchased Options [Member] \| Equity Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	0	0
Other Trading [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	62	75
Derivative Liability, Fair Value, Gross Liability	63	74
Derivative, Notional Amount	27,001	29,264
Secured Debt [Member] \| Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Receive-fixed Swaps, Fair Value, Gross Asset	0	0
Receive-fixed Swaps, Fair Value, Gross Liability	0	7
Receive-fixed Swaps, Notional Amount	0	240
Derivative assets in net asset position [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	78	87
Interest Receivable	3	7
Derivative assets in net liability positions [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2	8
Interest Receivable	$ 0	$ 1

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Pay-fixed Swaps on portfolios of held-for-investment automotive loan assets, Fair Value, Gross Asset

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Pay-fixed Swaps on portfolios of held-for-investment automotive loan assets, Fair Value, Notional Amount

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Receive-fixed Swaps on Fixed-rate Debt Obligations, Fair Value, Gross Asset

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Receive-fixed Swaps on Fixed-rate Debt Obligations, Notional Amount

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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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