Held-for-sale Operations - Assets and Liabilities of Operations Held-for-Sale (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets
Total assets	$ 1,975	$ 0
Liabilities
Total liabilities	17	$ 0
Disposal Group, Held-for-Sale, Not Discontinued Operations | Ally Lending
Assets
Loans held-for-sale, net	1,940
Other assets	35
Total assets	1,975
Liabilities
Accrued expenses and other liabilities	17
Total liabilities	17
Accrued interest and fees	25
Goodwill	4
Property, plant and equipment	4
Unfunded lending commitments	$ 5