Finance Receivables and Loans, Net (Financing Receivable Gross Charge-Offs) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	$ 1		$ 239
Year two, originated, current fiscal year, writeoff	182		1,034
Year three, originated, current fiscal year, writeoff	263		680
Year four, originated, current fiscal year, writeoff	153		197
Year five, originated, current fiscal year, writeoff	41		221
More than five years before current fiscal year, writeoff	49		151
Revolving loans	65		188
Revolving loans converted to term	4		10
Total	758	$ 601	2,720
Write-downs from transfers to held-for-sale	5
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	1		239
Year two, originated, current fiscal year, writeoff	182		1,034
Year three, originated, current fiscal year, writeoff	263		680
Year four, originated, current fiscal year, writeoff	153		197
Year five, originated, current fiscal year, writeoff	41		142
More than five years before current fiscal year, writeoff	49		123
Revolving loans	64		165
Revolving loans converted to term	4		10
Total	757		2,590
Consumer \| Automotive
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	1		225
Year two, originated, current fiscal year, writeoff	182		952
Year three, originated, current fiscal year, writeoff	263		651
Year four, originated, current fiscal year, writeoff	152		194
Year five, originated, current fiscal year, writeoff	41		142
More than five years before current fiscal year, writeoff	49		120
Revolving loans	0		0
Revolving loans converted to term	0		0
Total	688	536	2,284
Write-downs from transfers to held-for-sale	5		41
Consumer \| Consumer mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	0		0
Year two, originated, current fiscal year, writeoff	0		0
Year three, originated, current fiscal year, writeoff	0		0
Year four, originated, current fiscal year, writeoff	1		0
Year five, originated, current fiscal year, writeoff	0		0
More than five years before current fiscal year, writeoff	0		3
Revolving loans	0		0
Revolving loans converted to term	0		0
Total	1	1	3
Write-downs from transfers to held-for-sale	0
Consumer \| Mortgage Finance
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	0		0
Year two, originated, current fiscal year, writeoff	0		0
Year three, originated, current fiscal year, writeoff	0		0
Year four, originated, current fiscal year, writeoff	1		0
Year five, originated, current fiscal year, writeoff	0		0
More than five years before current fiscal year, writeoff	0		1
Revolving loans	0		0
Revolving loans converted to term	0		0
Total	1		1
Consumer \| Mortgage — Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff			0
Year two, originated, current fiscal year, writeoff			0
Year three, originated, current fiscal year, writeoff			0
Year four, originated, current fiscal year, writeoff			0
Year five, originated, current fiscal year, writeoff			0
More than five years before current fiscal year, writeoff			2
Revolving loans			0
Revolving loans converted to term			0
Total			2
Consumer \| Other
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	0		14
Year two, originated, current fiscal year, writeoff	0		82
Year three, originated, current fiscal year, writeoff	0		29
Year four, originated, current fiscal year, writeoff	0		3
Year five, originated, current fiscal year, writeoff	0		0
More than five years before current fiscal year, writeoff	0		0
Revolving loans	64		165
Revolving loans converted to term	4		10
Total	68	64	303
Write-downs from transfers to held-for-sale	0		174
Consumer \| Personal Lending
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff			14
Year two, originated, current fiscal year, writeoff			82
Year three, originated, current fiscal year, writeoff			29
Year four, originated, current fiscal year, writeoff			3
Year five, originated, current fiscal year, writeoff			0
More than five years before current fiscal year, writeoff			0
Revolving loans			0
Revolving loans converted to term			0
Total			128
Consumer \| Credit Card
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	0		0
Year two, originated, current fiscal year, writeoff	0		0
Year three, originated, current fiscal year, writeoff	0		0
Year four, originated, current fiscal year, writeoff	0		0
Year five, originated, current fiscal year, writeoff	0		0
More than five years before current fiscal year, writeoff	0		0
Revolving loans	64		165
Revolving loans converted to term	4		10
Total	68		175
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	0		0
Year two, originated, current fiscal year, writeoff	0		0
Year three, originated, current fiscal year, writeoff	0		0
Year four, originated, current fiscal year, writeoff	0		0
Year five, originated, current fiscal year, writeoff	0		79
More than five years before current fiscal year, writeoff	0		28
Revolving loans	1		23
Revolving loans converted to term	0		0
Total	1	$ 0	130
Write-downs from transfers to held-for-sale	0
Commercial \| Automotive
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff	0		0
Year two, originated, current fiscal year, writeoff	0		0
Year three, originated, current fiscal year, writeoff	0		0
Year four, originated, current fiscal year, writeoff	0		0
Year five, originated, current fiscal year, writeoff	0		0
More than five years before current fiscal year, writeoff	0		5
Revolving loans	1		19
Revolving loans converted to term	0		0
Total	$ 1		24
Commercial \| Other
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, originated, current fiscal year, writeoff			0
Year two, originated, current fiscal year, writeoff			0
Year three, originated, current fiscal year, writeoff			0
Year four, originated, current fiscal year, writeoff			0
Year five, originated, current fiscal year, writeoff			79
More than five years before current fiscal year, writeoff			23
Revolving loans			4
Revolving loans converted to term			0
Total			$ 106

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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Amount, excluding accrued interest, of reversal of credit loss expense on financing receivable transferred out of held-for-investment into held-for-sale classification. Excludes net investment in lease.

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