Fair Value (Fair Value Measurements - Reconciliation of Level 3 Assets And Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			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	$ 14	$ 5	20	12
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	681	156	990	246
Fair value, measurement, recurring, asset, sales	(661)	(152)	(930)	(236)
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	(6)	(5)	(13)	(5)
Fair value, assets, recurring, net unrealized gains (losses)	6	2	9	8
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	2	(3)	6
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	(4)	0	(4)
Fair value, assets, recurring, net unrealized gains (losses)	1	2	(3)	6
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		3
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	8	3	13	4
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	676	156	978	246
Fair value, measurement, recurring, asset, sales	(661)	(152)	(930)	(236)
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)	1	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	1		0
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0		0
Fair value, measurement, recurring, asset, purchases	3		9
Fair value, measurement, recurring, asset, sales	0		0
Fair value, measurement , recurring, asset, issuances	0		0
Fair value, measurement, recurring, asset, settlements	(6)		(12)
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	0	(1)	(1)	(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	4	0	10	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)	4	0	10	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	94	32	55	19
Fair value, measurement, recurring, asset value, ending balance	122	36	122	36
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	4	11	8	7
Fair value, measurement, recurring, asset value, ending balance	5	9	5	9
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	3		2
Fair value, measurement, recurring, asset value, ending balance	5		5
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	68	15	30	8
Fair value, measurement, recurring, asset value, ending balance	91	22	91	22
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	10		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	4	2	4
Fair value, measurement, recurring, asset value, ending balance	1	3	1	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	8	2	2	0
Fair value, measurement, recurring, asset value, ending balance	$ 12	$ 2	$ 12	$ 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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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-SubTopic 10
-Section 50
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-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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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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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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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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