Contingencies and Other Risks	12 Months Ended
Contingencies and Other Risks	Dec. 31, 2023
Loss Contingency [Abstract]
Contingencies and Other Risks	Contingencies and Other Risks Concentration with GM and Stellantis While we continue to diversify our automotive finance and insurance businesses and expand into other financial services, GM and Stellantis dealers and their retail customers continue to constitute a significant portion of our customer base. GM, Stellantis, and their captive finance companies compete vigorously with us and could take further actions that negatively impact the amount of business that we do with GM and Stellantis dealers and their customers. A significant adverse change in GM’s or Stellantis’ business—including, for example, in the production or sale of GM or Stellantis vehicles, the quality or resale value of GM or Stellantis vehicles, GM’s or Stellantis’ relationships with its key suppliers, or the rate or volume of recalls of GM or Stellantis vehicles—could negatively impact our GM and Stellantis dealer and retail customer bases and the value of collateral securing our extensions of credit to them. Any future reductions in GM and Stellantis business that we are not able to offset could adversely affect our business and financial results. Legal Matters and Other Contingencies As a financial-services company, we are regularly involved in pending or threatened legal proceedings and other matters and are or may be subject to potential liability in connection with them. These legal matters may be formal or informal and include litigation and arbitration with one or more identified claimants, certified or purported class actions with yet-to-be-identified claimants, and regulatory or other governmental information-gathering requests, examinations, investigations, and enforcement proceedings. Our legal matters exist in varying stages of adjudication, arbitration, negotiation, or investigation and span our business lines and operations. Claims may be based in law or equity—such as those arising under contracts or in tort and those involving banking, consumer-protection, securities, tax, employment, and other laws—and some can present novel legal theories and allege substantial or indeterminate damages. Ally and its subsidiaries, including Ally Bank, also are or may be subject to potential liability under other contingent exposures, including indemnification, tax, self-insurance, and other miscellaneous contingencies. We accrue for a legal matter or other contingent exposure when a loss becomes probable and the amount of loss can be reasonably estimated. Accruals are evaluated each quarter and may be adjusted, upward or downward, based on our best judgment after consultation with counsel. No assurance exists that our accruals will not need to be adjusted in the future. When a probable or reasonably possible loss on a legal matter or other contingent exposure could be material to our consolidated financial condition, results of operations, or cash flows, we provide disclosure in this note as prescribed by ASC Topic 450, Contingencies. Refer to Note 1 for additional information related to our policy for establishing accruals. The course and outcome of legal matters are inherently unpredictable. This is especially so when a matter is still in its early stages, the damages sought are indeterminate or unsupported, significant facts are unclear or disputed, novel questions of law or other meaningful legal uncertainties exist, a request to certify a proceeding as a class action is outstanding or granted, multiple parties are named, or regulatory or other governmental entities are involved. Other contingent exposures and their ultimate resolution are similarly unpredictable for reasons that can vary based on the circumstances. As a result, we often are unable to determine how or when threatened or pending legal matters and other contingent exposures will be resolved and what losses may be incrementally and ultimately incurred. Actual losses may be higher or lower than any amounts accrued or estimated for those matters and other exposures, possibly to a significant degree. Subject to the foregoing, based on our current knowledge and after consultation with counsel, we do not believe that the ultimate outcomes of currently threatened or pending legal matters and other contingent exposures are likely to be material to our consolidated financial condition after taking into account existing accruals. In light of the uncertainties inherent in these matters and other exposures, however, one or more of them could be material to our results of operations or cash flows during a particular reporting period, depending on factors such as the amount of the loss or liability and the level of our income for that period.

The entire disclosure for loss and gain contingencies. Describes any existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible loss incurred by an entity that will ultimately be resolved when one or more future events occur or fail to occur, and typically discloses the amount of loss recorded or a range of possible loss, or an assertion that no reasonable estimate can be made.