Held-for-sale Operations - Schedule of Assets and Liabilities of Operations Held-for-Sale (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Assets
Total assets	$ 0	$ 1,975
Liabilities
Total liabilities	$ 0	17
Disposal Group, Held-for-Sale or Disposed of by 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