Held-for-sale Operations - Schedule of Assets and Liabilities of Operations Held-for-Sale (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Assets
Total assets	$ 2,440	$ 0
Liabilities
Total liabilities	35	$ 0
Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations | Ally Credit Card
Assets
Loans held-for-sale, net	2,248
Other assets	192
Total assets	2,440
Liabilities
Accrued expenses and other liabilities	35
Total liabilities	35
Goodwill	56
Intangible assets	51
Cash in transit	51
Accrued unbilled interest receivable	$ 20