Fair Value (Fair Value Measurements - Reconciliation of Level 3 Assets And Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	$ 36	$ 30	$ 19	$ 38
Fair value, measurement, recurring, asset, gain (loss) included in earnings	2	2	14	0
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	222	86	468	218
Fair value, measurement, recurring, asset, sales	(209)	(88)	(445)	(222)
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	0	(1)	(5)	(5)
Fair value, measurement, recurring, asset value, ending balance	51	29	51	29
Fair value, assets, recurring, net unrealized gains (losses)	(1)	(1)	7	(6)
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0		0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	9	12	7	19
Fair value, measurement, recurring, asset, gain (loss) included in earnings	(1)	0	5	(4)
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)	(4)	(4)
Fair value, measurement, recurring, asset value, ending balance	8	11	8	11
Fair value, assets, recurring, net unrealized gains (losses)	(1)	(1)	5	(6)
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 value, beginning balance	22	13	8	13
Fair value, measurement, recurring, asset, gain (loss) included in earnings	3	2	7	4
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0	0	0
Fair value, measurement, recurring, asset, purchases	222	86	468	218
Fair value, measurement, recurring, asset, sales	(209)	(88)	(445)	(222)
Fair value, measurement , recurring, asset, issuances	0	0	0	0
Fair value, measurement, recurring, asset, settlements	0	0	0	0
Fair value, measurement, recurring, asset value, ending balance	38	13	38	13
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
Retained interest
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	3	4	4	5
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	0	(1)	(1)
Fair value, measurement, recurring, asset value, ending balance	3	4	3	4
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
Derivative
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	2	1	0	1
Fair value, measurement, recurring, asset, gain (loss) included in earnings	0	0	2	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	0	0	0
Fair value, measurement, recurring, asset value, ending balance	2	1	2	1
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

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)
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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).

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-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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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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