Contingencies and Other Risks	12 Months Ended
Dec. 31, 2016
Loss Contingency [Abstract]
Contingencies Disclosure [Text Block]	Contingencies and Other Risks Concentration with GM and Chrysler While we are continuing to diversify our automotive finance and insurance businesses and to expand into other financial services, General Motors Company (GM) and Fiat Chrysler Automobiles US LLC (Chrysler) dealers and their retail customers continue to constitute a significant portion of our customer base. GM, Chrysler, and their captive finance companies compete forcefully with us and could take further actions that negatively impact the amount of business that we do with GM and Chrysler dealers and their customers. Further, a significant adverse change in GM’s or Chrysler’s business—including, for example, in the production or sale of GM or Chrysler vehicles, the quality or resale value of GM or Chrysler vehicles, GM’s or Chrysler’s relationships with its key suppliers, or the rate or volume of recalls of GM or Chrysler vehicles—could negatively impact our GM and Chrysler dealer and retail customer bases. Any future reductions in GM and Chrysler business that we are not able to offset could adversely affect our business and financial results. Legal Matters Ally and its subsidiaries, including Ally Bank, are or may be subject to potential liability in connection with pending or threatened legal proceedings and other matters. 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 lines of business 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. We accrue for a legal matter 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. 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. As a result, we cannot state with confidence how or when threatened or pending legal matters will be resolved and what losses may be incurred. Actual losses may be higher or lower than any amounts accrued for those matters, possibly to a significant degree. On the basis of information currently available, advice of counsel, available insurance coverage, and established reserves, it is the opinion of management that, except as described in the next paragraph, the eventual outcome of our existing legal matters will not have a material adverse effect on our consolidated financial condition, results of operations, or cash flows. It is possible, however, that an unfavorable resolution of legal matters may be material to our consolidated financial condition, results of operations, or cash flows in a particular period. Descriptions of our material legal matters follow. In each case, the matter could have material adverse consequences for us, including substantial damages or settlements, injunctions, governmental fines or penalties, and reputational or operational risks. We do not believe, however, that an estimate of reasonably possible losses or a range of reasonably possible losses in excess of established reserves—whether in excess of any related accrual or where no accrual exists—can be made for any of these matters. Securities Litigation In October 2016, a purported class action—Bucks County Employees Retirement Fund v. Ally Financial Inc. et al.—was filed in the Circuit Court for Wayne County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on November 18, 2016, and is currently pending there as Case No. 2:16-CV-14104. The complaint alleges material misstatements and omissions in connection with Ally’s initial public offering in April 2014, including a failure to adequately disclose the severity of rising subprime automotive loan delinquency rates, deficient underwriting measures employed in the origination of subprime automotive loans, and aggressive tactics used with low-income borrowers. The request for relief includes an indeterminate amount of damages, fees, and costs and other remedies. In January 2017, another purported class action—National Shopmen Pension Fund v. Ally Financial Inc. et al.—was filed in the Circuit Court for Oakland County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on January 30, 2017, and is currently pending there as Case No. 2:17-CV-10289. The allegations and requested relief in the complaint are substantially similar to those included in the complaint filed by Bucks County Employees Retirement Fund. We intend to vigorously defend against these actions. Automotive Subprime Matters In October 2014, we received a document request from the SEC in connection with its investigation related to subprime automotive finance and related securitization activities. Separately, in December 2014, we received a subpoena from the DOJ requesting similar information. In May 2015 and December 2016, we received information requests from the New York Department of Financial Services requesting similar information. We have cooperated with each of these agencies with respect to these matters. Indirect Automotive Finance Matters In December 2013, Ally Financial Inc. and Ally Bank entered into a Consent Order issued by the U.S. Consumer Financial Protection Bureau (CFPB) and a Consent Order jointly submitted with the DOJ and entered by the U.S. District Court for the Eastern District of Michigan (United States v. Ally Financial Inc. and Ally Bank, Civil Action No. 13-15180), in each case, pertaining to allegations of discrimination involving the automotive finance business. The Consent Orders require Ally to create a compliance plan addressing, at a minimum, the communication of Ally’s expectations of Equal Credit Opportunity Act (ECOA) compliance to our automotive dealer clients, maintenance of Ally’s existing limits on dealer finance income for contracts acquired by Ally, and monitoring for potential discrimination both at the dealer level and within our portfolio of contracts acquired across all of our automotive dealer clients. Ally formed a compliance committee consisting of certain Ally Financial Inc. and Ally Bank directors to oversee Ally’s execution of the Consent Orders’ terms. Ally is required to meet certain stipulations under the Consent Orders, including a requirement to make monetary payments when ongoing remediation targets are not attained. Since 2013, Ally has recognized expenses of approximately $240 million for judgments, fines, and monetary remuneration payments to customers related to the Consent Orders. The Consent Orders terminate, according to their terms, in 2017, and preclude the CFPB and the DOJ from pursuing any potential violations of the ECOA against Ally Financial Inc. or Ally Bank for conduct undertaken pursuant to the Consent Orders during the period of the Consent Orders. If the CFPB or the DOJ were to assert that Ally Financial Inc. or Ally Bank is violating the ECOA after the Consent Orders terminate, further legal proceedings could occur. Mortgage Matters We previously disclosed investigations by the DOJ relating to residential mortgage-backed securities issued by our former mortgage subsidiary, Residential Capital, LLC and its subsidiaries (ResCap RMBS). The DOJ was investigating potential fraud and other potential legal claims related to ResCap RMBS, including potential claims under the Financial Institutions Reform, Recovery, and Enforcement Act of 1989, as well as potential claims under the False Claims Act related to representations made by us in connection with investments in Ally Financial Inc. made by the U.S. Department of the Treasury pursuant to the Troubled Asset Relief Program in 2008 and 2009 regarding certain claims against Residential Capital, LLC or its subsidiaries at that time. On November 21, 2016, we comprehensively resolved these investigations and potential claims with the DOJ and entered into a settlement agreement. Under the agreement, we in 2016 (1) paid $52 million to the DOJ, which is included in discontinued operations, (2) withdrew the broker-dealer registration for Ally Securities LLC (formerly known as Residential Funding Securities LLC) (Ally Securities), which is one of our wholly-owned subsidiaries, and (3) began to wind down the affairs of Ally Securities. Other Contingencies Ally and its subsidiaries, including Ally Bank, are or may be subject to potential liability under various other contingent exposures, including indemnification, tax, self-insurance, and other miscellaneous contingencies. We accrue for a 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. No assurance exists that our accruals will not need to be adjusted in the future, and actual losses may be higher or lower than any amounts accrued for those exposures, possibly to a significant degree. On the basis of information currently available, available insurance coverage, and established reserves, it is the opinion of management that the eventual outcome of our other contingent exposures will not have a material adverse effect on our consolidated financial condition, results of operations, or cash flows.

Contingencies and Other Risks

Concentration with GM and Chrysler

While we are continuing to diversify our automotive finance and insurance businesses and to expand into other financial services, General Motors Company (GM) and Fiat Chrysler Automobiles US LLC (Chrysler) dealers and their retail customers continue to constitute a significant portion of our customer base. GM, Chrysler, and their captive finance companies compete forcefully with us and could take further actions that negatively impact the amount of business that we do with GM and Chrysler dealers and their customers. Further, a significant adverse change in GM’s or Chrysler’s business—including, for example, in the production or sale of GM or Chrysler vehicles, the quality or resale value of GM or Chrysler vehicles, GM’s or Chrysler’s relationships with its key suppliers, or the rate or volume of recalls of GM or Chrysler vehicles—could negatively impact our GM and Chrysler dealer and retail customer bases. Any future reductions in GM and Chrysler business that we are not able to offset could adversely affect our business and financial results.

Legal Matters

Ally and its subsidiaries, including Ally Bank, are or may be subject to potential liability in connection with pending or threatened legal proceedings and other matters. 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 lines of business 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.

We accrue for a legal matter 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.

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. As a result, we cannot state with confidence how or when threatened or pending legal matters will be resolved and what losses may be incurred. Actual losses may be higher or lower than any amounts accrued for those matters, possibly to a significant degree.

On the basis of information currently available, advice of counsel, available insurance coverage, and established reserves, it is the opinion of management that, except as described in the next paragraph, the eventual outcome of our existing legal matters will not have a material adverse effect on our consolidated financial condition, results of operations, or cash flows. It is possible, however, that an unfavorable resolution of legal matters may be material to our consolidated financial condition, results of operations, or cash flows in a particular period.

Descriptions of our material legal matters follow. In each case, the matter could have material adverse consequences for us, including substantial damages or settlements, injunctions, governmental fines or penalties, and reputational or operational risks. We do not believe, however, that an estimate of reasonably possible losses or a range of reasonably possible losses in excess of established reserves—whether in excess of any related accrual or where no accrual exists—can be made for any of these matters.

Securities Litigation

In October 2016, a purported class action—Bucks County Employees Retirement Fund v. Ally Financial Inc. et al.—was filed in the Circuit Court for Wayne County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on November 18, 2016, and is currently pending there as Case No. 2:16-CV-14104. The complaint alleges material misstatements and omissions in connection with Ally’s initial public offering in April 2014, including a failure to adequately disclose the severity of rising subprime automotive loan delinquency rates, deficient underwriting measures employed in the origination of subprime automotive loans, and aggressive tactics used with low-income borrowers. The request for relief includes an indeterminate amount of damages, fees, and costs and other remedies. In January 2017, another purported class action—National Shopmen Pension Fund v. Ally Financial Inc. et al.—was filed in the Circuit Court for Oakland County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on January 30, 2017, and is currently pending there as Case No. 2:17-CV-10289. The allegations and requested relief in the complaint are substantially similar to those included in the complaint filed by Bucks County Employees Retirement Fund. We intend to vigorously defend against these actions.

Automotive Subprime Matters

In October 2014, we received a document request from the SEC in connection with its investigation related to subprime automotive finance and related securitization activities. Separately, in December 2014, we received a subpoena from the DOJ requesting similar information. In May 2015 and December 2016, we received information requests from the New York Department of Financial Services requesting similar information. We have cooperated with each of these agencies with respect to these matters.

Indirect Automotive Finance Matters

In December 2013, Ally Financial Inc. and Ally Bank entered into a Consent Order issued by the U.S. Consumer Financial Protection Bureau (CFPB) and a Consent Order jointly submitted with the DOJ and entered by the U.S. District Court for the Eastern District of Michigan (United States v. Ally Financial Inc. and Ally Bank, Civil Action No. 13-15180), in each case, pertaining to allegations of discrimination involving the automotive finance business. The Consent Orders require Ally to create a compliance plan addressing, at a minimum, the communication of Ally’s expectations of Equal Credit Opportunity Act (ECOA) compliance to our automotive dealer clients, maintenance of Ally’s existing limits on dealer finance income for contracts acquired by Ally, and monitoring for potential discrimination both at the dealer level and within our portfolio of contracts acquired across all of our automotive dealer clients. Ally formed a compliance committee consisting of certain Ally Financial Inc. and Ally Bank directors to oversee Ally’s execution of the Consent Orders’ terms. Ally is required to meet certain stipulations under the Consent Orders, including a requirement to make monetary payments when ongoing remediation targets are not attained.

Since 2013, Ally has recognized expenses of approximately $240 million for judgments, fines, and monetary remuneration payments to customers related to the Consent Orders. The Consent Orders terminate, according to their terms, in 2017, and preclude the CFPB and the DOJ from pursuing any potential violations of the ECOA against Ally Financial Inc. or Ally Bank for conduct undertaken pursuant to the Consent Orders during the period of the Consent Orders. If the CFPB or the DOJ were to assert that Ally Financial Inc. or Ally Bank is violating the ECOA after the Consent Orders terminate, further legal proceedings could occur.

Mortgage Matters

We previously disclosed investigations by the DOJ relating to residential mortgage-backed securities issued by our former mortgage subsidiary, Residential Capital, LLC and its subsidiaries (ResCap RMBS). The DOJ was investigating potential fraud and other potential legal claims related to ResCap RMBS, including potential claims under the Financial Institutions Reform, Recovery, and Enforcement Act of 1989, as well as potential claims under the False Claims Act related to representations made by us in connection with investments in Ally Financial Inc. made by the U.S. Department of the Treasury pursuant to the Troubled Asset Relief Program in 2008 and 2009 regarding certain claims against Residential Capital, LLC or its subsidiaries at that time.

On November 21, 2016, we comprehensively resolved these investigations and potential claims with the DOJ and entered into a settlement agreement. Under the agreement, we in 2016 (1) paid $52 million to the DOJ, which is included in discontinued operations, (2) withdrew the broker-dealer registration for Ally Securities LLC (formerly known as Residential Funding Securities LLC) (Ally Securities), which is one of our wholly-owned subsidiaries, and (3) began to wind down the affairs of Ally Securities.

Other Contingencies

Ally and its subsidiaries, including Ally Bank, are or may be subject to potential liability under various other contingent exposures, including indemnification, tax, self-insurance, and other miscellaneous contingencies. We accrue for a 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. No assurance exists that our accruals will not need to be adjusted in the future, and actual losses may be higher or lower than any amounts accrued for those exposures, possibly to a significant degree. On the basis of information currently available, available insurance coverage, and established reserves, it is the opinion of management that the eventual outcome of our other contingent exposures will not have a material adverse effect on our consolidated financial condition, results of operations, or cash flows.