Fair Value (Fair Value Measurements - Reconciliation of Level 3 Assets And Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 0	$ 0	$ 0	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0	0	0	0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	31	2	51	14
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	861	222	1,851	468
Fair value, measurement, recurring, asset, sales	(811)	(209)	(1,741)	(445)
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	(8)	0	(21)	(5)
Fair value, assets, recurring, net unrealized gains (losses)	7	(1)	16	7
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	1	(1)	(2)	5
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	0	0	0	0
Fair value, measurement, recurring, asset, sales	0	0	0	0
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	0	0	0	(4)
Fair value, assets, recurring, net unrealized gains (losses)	1	(1)	(2)	5
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0	0	0
Available-for-sale securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	0		0
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0		0
Fair value, measurement, recurring, asset, purchases	2		5
Fair value, measurement, recurring, asset, sales	0		0
Fair value, measurement , recurring, asset, issuances	0		0
Fair value, measurement, recurring, asset, settlements	0		0
Fair value, assets, recurring, net unrealized gains (losses)	0		0
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0		0
Loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	22	3	35	7
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	854	222	1,832	468
Fair value, measurement, recurring, asset, sales	(811)	(209)	(1,741)	(445)
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	0	0	0	0
Fair value, assets, recurring, net unrealized gains (losses)	0	0	2	0
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0	0	0
Finance receivables and Loans, net \| Consumer Loan
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	2		2
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0		0
Fair value, measurement, recurring, asset, purchases	5		14
Fair value, measurement, recurring, asset, sales	0		0
Fair value, measurement , recurring, asset, issuances	0		0
Fair value, measurement, recurring, asset, settlements	(7)		(19)
Fair value, assets, recurring, net unrealized gains (losses)	0		0
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0		0
Interests retained in financial asset sales
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	0	0	0	0
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	0	0	0	0
Fair value, measurement, recurring, asset, sales	0	0	0	0
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	(1)	0	(2)	(1)
Fair value, assets, recurring, net unrealized gains (losses)	0	0	0	0
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0	0	0
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset, gain (loss) included in earnings	6	0	16	2
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	0	0	0	0
Fair value, measurement, recurring, asset, sales	0	0	0	0
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	0	0	0	0
Fair value, assets, recurring, net unrealized gains (losses)	6	0	16	2
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0	0	0
Fair value, measurements, recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	122	36	55	19
Fair value, measurement, recurring, asset value, ending balance	195	51	195	51
Fair value, measurements, recurring \| Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	5	9	8	7
Fair value, measurement, recurring, asset value, ending balance	6	8	6	8
Fair value, measurements, recurring \| Available-for-sale securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	5		2
Fair value, measurement, recurring, asset value, ending balance	7		7
Fair value, measurements, recurring \| Loans held-for-sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	91	22	30	8
Fair value, measurement, recurring, asset value, ending balance	156	38	156	38
Fair value, measurements, recurring \| Finance receivables and Loans, net \| Consumer Loan
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	8		11
Fair value, measurement, recurring, asset value, ending balance	8		8
Fair value, measurements, recurring \| Interests retained in financial asset sales
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	1	3	2	4
Fair value, measurement, recurring, asset value, ending balance	0	3	0	3
Fair value, measurements, recurring \| Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	12	2	2	0
Fair value, measurement, recurring, asset value, ending balance	$ 18	$ 2	$ 18	$ 2

Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset (liability) measured at fair value on recurring basis using unobservable input (level 3) and still held.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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