Fair Value (Fair Value Measurements - Reconciliation of Level 3 Assets And Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 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	70	20
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0
Fair value, measurement, recurring, asset, purchases	2,757	759
Fair value, measurement, recurring, asset, sales	(2,740)	(732)
Fair value, measurement , recurring, asset, issuances	0	0
Fair value, measurement, recurring, asset, settlements	(27)	(11)
Fair value, assets, recurring, net unrealized gains (losses)	0	7
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	(10)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances	24
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	0
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	(10)
Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0
Derivative liabilities, net of derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	(10)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances	24
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	0
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	(10)
Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	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)	5
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0
Fair value, measurement, recurring, asset, purchases	0	0
Fair value, measurement, recurring, asset, sales	0	0
Fair value, measurement , recurring, asset, issuances	0	0
Fair value, measurement, recurring, asset, settlements	0	(4)
Fair value, assets, recurring, net unrealized gains (losses)	(1)	5
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	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	5	2
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
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, liabilities 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	67	12
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0
Fair value, measurement, recurring, asset, purchases	2,734	742
Fair value, measurement, recurring, asset, sales	(2,740)	(732)
Fair value, measurement , recurring, asset, issuances	0	0
Fair value, measurement, recurring, asset, settlements	0	0
Fair value, assets, recurring, net unrealized gains (losses)	1	0
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	0	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	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	4	1
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0
Fair value, measurement, recurring, asset, purchases	18	15
Fair value, measurement, recurring, asset, sales	0	0
Fair value, measurement , recurring, asset, issuances	0	0
Fair value, measurement, recurring, asset, settlements	(25)	(5)
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
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, liabilities 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
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)	0	0
Fair value, measurement, recurring, asset, purchases	0	0
Fair value, measurement, recurring, asset, sales	0	0
Fair value, measurement , recurring, asset, issuances	0	0
Fair value, measurement, recurring, asset, settlements	(2)	(2)
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
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income	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		2
Fair value, measurement, recurring, asset, gain (loss) included in other comprehensive income (loss)		0
Fair value, measurement, recurring, asset, purchases		0
Fair value, measurement, recurring, asset, sales		0
Fair value, measurement , recurring, asset, issuances		0
Fair value, measurement, recurring, asset, settlements		0
Fair value, assets, recurring, net unrealized gains (losses)		2
Fair value, assets measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income		0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, liabilities measured on recurring basis, change in unrealized gain (loss) included in other comprehensive income		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	55	19
Fair value, measurement, recurring, asset value, ending balance	113	55
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Beginning Balance	(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	12	(2)
Fair value, measurements, recurring | Excludes derivative assets, net of derivative liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	53
Fair value, measurement, recurring, asset value, ending balance		53
Fair value, measurements, recurring | Derivative liabilities, net of derivative assets
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Beginning Balance	(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	12	(2)
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	8	7
Fair value, measurement, recurring, asset value, ending balance	7	8
Fair value, measurements, recurring | Equity securities | Excludes derivative assets, net of derivative liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	8
Fair value, measurement, recurring, asset value, ending balance		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	2	0
Fair value, measurement, recurring, asset value, ending balance	7	2
Fair value, measurements, recurring | Available-for-sale securities | Excludes derivative assets, net of derivative liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	2
Fair value, measurement, recurring, asset value, ending balance		2
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	30	8
Fair value, measurement, recurring, asset value, ending balance	91	30
Fair value, measurements, recurring | Loans held-for-sale | Excludes derivative assets, net of derivative liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	30
Fair value, measurement, recurring, asset value, ending balance		30
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	11	0
Fair value, measurement, recurring, asset value, ending balance	8	11
Fair value, measurements, recurring | Finance receivables and Loans, net | Consumer Loan | Excludes derivative assets, net of derivative liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	11
Fair value, measurement, recurring, asset value, ending balance		11
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	2	4
Fair value, measurement, recurring, asset value, ending balance	0	2
Fair value, measurements, recurring | Interests retained in financial asset sales | Excludes derivative assets, net of derivative liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, measurement, recurring, asset value, beginning balance	2
Fair value, measurement, recurring, asset value, ending balance		2
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	$ 2	0
Fair value, measurement, recurring, asset value, ending balance		$ 2