Finance Receivables and Loans, Net (Schedule of Accounts, Notes, Loans and Financing Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 114,471		$ 118,534
Unamortized premiums and discounts and deferred fees and costs	2,300		2,000
Accrued interest receivable	487		587
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	95,052		89,202
Consumer | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	77,761		73,668
Consumer | Mortgage/Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	16,455		15,127
Consumer | Mortgage Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	16,059		14,632
Interest-only mortgage loans	6		8
Consumer | Mortgage - Legacy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	396		495
Interest-only mortgage loans	$ 23		30
Interest-only mortgage loans having exited the interest-only period	98.00%
Consumer | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 836		407
Finance receivables, fair value	8	$ 8	8	$ 8	$ 8	$ 11
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	19,419		29,332
Commercial | Automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	8,772		19,082
Commercial | Mortgage/Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	4,788		5,008
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 5,859		$ 5,242