Finance Receivables and Loans, Net (Schedule of Accounts, Notes, Loans and Financing Receivables) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 112,217		$ 118,534
Unamortized premiums and discounts and deferred fees and costs	2,200		2,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	90,649		89,202
Consumer | Consumer automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	75,951		73,668
Consumer | Consumer mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	14,058		15,127
Consumer | Mortgage Finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	13,629		14,632
Interest-only mortgage loans	6		8
Consumer | Mortgage - Legacy
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	429		495
Interest-only mortgage loans	$ 25		30
Interest-only mortgage loans having exited the interest-only period	99.00%
Consumer | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	$ 640		407
Finance receivables, fair value	8	$ 8	8	$ 8	$ 10	$ 11
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	21,568		29,332
Commercial | Consumer automotive
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	11,303		19,082
Commercial | Consumer mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	4,823		5,008
Commercial | Consumer other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total finance receivables and loans	5,442		5,242
Finance receivables and loans, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable	$ 475		$ 587