Derivative Instruments and Hedging Activities (Fair Value Amounts of Derivative Instruments Reported on our Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 95	$ 233
Derivative Liability, Fair Value, Gross Liability	95	145
Derivative, Notional Amount	34,166	59,116
Interest Receivable	476	402
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	20	126
Derivative Liability, Fair Value, Gross Liability	21	10
Derivative, Notional Amount	4,902	14,340
Interest Rate Swap [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	19	126
Derivative Liability, Fair Value, Gross Liability	21	9
Derivative, Notional Amount	4,731	14,151
Hedge notional amount associated with debt maturing in five or more years	1,700
Foreign Exchange Forward [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	0
Derivative Liability, Fair Value, Gross Liability	0	1
Derivative, Notional Amount	171	189
Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Receive-fixed Swaps, Fair Value, Gross Asset	8	112
Receive-fixed Swaps, Fair Value, Gross Liability	14	3
Receive-fixed Swaps, Notional Amount	1,700	6,800
Pay-fixed Swaps, Fair Value, Gross Asset	10	13
Pay-fixed Swaps, Fair Value, Gross Liability	1	3
Pay-fixed Swaps, Notional Amount	2,800	6,800
Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	73	105
Derivative Liability, Fair Value, Gross Liability	73	125
Derivative, Notional Amount	29,172	44,466
Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	92	278
Equity Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	2
Derivative Liability, Fair Value, Gross Liability	1	10
Derivative, Notional Amount	0	32
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	30
Derivative Liability, Fair Value, Gross Liability	0	51
Derivative, Notional Amount	137	6,101
Foreign Exchange Forward [Member] \| Foreign Exchange Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	92	278
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	2
Derivative Liability, Fair Value, Gross Liability	0	2
Derivative, Notional Amount	0	1,905
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	73	72
Derivative, Notional Amount	14,518	18,220
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	1	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	73	73
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	14,517	18,240
Purchased Options [Member] \| Equity Contract [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	2
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	0	0
Forward Contracts [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	9
Derivative, Notional Amount	0	32
Other Trading [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	75	107
Derivative Liability, Fair Value, Gross Liability	74	135
Derivative, Notional Amount	29,264	44,776
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	1
Receive-fixed Swaps, Fair Value, Gross Liability	7	2
Receive-fixed Swaps, Notional Amount	240	500
Derivative assets in net asset position [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	87	224
Interest Receivable	7	46
Derivative assets in net liability positions [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	8	9
Interest Receivable	$ 1	$ 12

Hedge notional amount associated with debt maturing in five or more years

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- Definition

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

+ References

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

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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, Fair Value, Gross Liability

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

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No definition available.

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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)
-Number 210
-Article 12
-Section 13
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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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- Definition

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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No definition available.

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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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