Derivative Instruments and Hedging Activities (Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Long-term debt	$ 45,542	$ 44,226
Hedged asset, last-of-layer, amount	19,400
Hedge basis adjustment, last-of-layer	60
Carrying amount
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Available-for-sale debt securities	1,433	173
Finance receivables and loans, net	41,080	2,305
Long-term debt	14,200	14,640
Fair value hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Available-for-sale debt securities	4	2
Finance receivables and loans, net	(52)	18
Long-term debt	62	208
Discontinued hedge
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Available-for-sale debt securities	4	2
Finance receivables and loans, net	8	19
Long-term debt	$ 87	$ 235

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of asset hedged in last of layer, expected to be remaining at end of hedging relationship.

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Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk, in last-of-layer hedging relationship.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

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