Description Of Business, Basis Of Presentation, And Changes In Significant Accounting Policies	9 Months Ended
Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]	Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies Ally Financial Inc. (referred to herein as Ally, we, our, or us) is a leading, independent, diversified financial services firm. Founded in 1919, we are a leading financial services company with more than 95 years of experience providing a broad array of financial products and services, primarily to automotive dealers and retail customers. We operate as a financial holding company (FHC) and a bank holding company (BHC). Our banking subsidiary, Ally Bank, is an indirect, wholly-owned subsidiary of Ally Financial Inc. and a leading franchise in the growing direct (internet, telephone, mobile, and mail) banking market. Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America (GAAP). Additionally, where applicable, the policies conform to the accounting and reporting guidelines prescribed by bank regulatory authorities. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and that affect income and expenses during the reporting period and related disclosures. In developing the estimates and assumptions, management uses all available evidence; however, actual results could differ because of uncertainties associated with estimating the amounts, timing, and likelihood of possible outcomes. The Condensed Consolidated Financial Statements at September 30, 2015, and for the three months and nine months ended September 30, 2015, and 2014, are unaudited but reflect all adjustments that are, in management’s opinion, necessary for the fair presentation of the results for the interim periods presented. All such adjustments are of a normal recurring nature. These unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements (and the related notes) included in our Annual Report on Form 10-K for the year ended December 31, 2014, as filed on February 27, 2015, with the U.S. Securities and Exchange Commission (SEC). Significant Accounting Policies Income Taxes In calculating the provision for interim income taxes, in accordance with Accounting Standards Codification (ASC) 740, Income Taxes, we apply an estimated annual effective tax rate to year-to-date ordinary income. At the end of each interim period, we estimate the effective tax rate expected to be applicable for the full fiscal year. This method differs from that described in Note 1 to the Consolidated Financial Statements in our 2014 Annual Report on Form 10-K, which describes our annual significant income tax accounting policy and related methodology. Refer to Note 1 to the Consolidated Financial Statements in our 2014 Annual Report on Form 10-K regarding additional significant accounting policies. Recently Adopted Accounting Standards Receivables — Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure (ASU 2014-04) As of January 1, 2015, we adopted ASU (Accounting Standards Update) 2014-04. The amendments in this ASU clarify the timing for which an entity should reclassify a loan that has been foreclosed or where an in substance repossession has occurred to real estate owned. The guidance requires a reclassification to occur when the entity obtains legal title upon completion of foreclosure or the borrower conveys all interest in the residential real estate property to the entity to satisfy the loan through completion of a deed in lieu of foreclosure or similar legal agreement. In addition, the ASU clarifies that redemption rights of the borrower should be ignored for purposes of determining whether legal title has transferred. We adopted the guidance utilizing a modified retrospective approach. The adoption of this guidance did not have a material effect on our consolidated financial condition or results of operations. Presentation of Financial Statements and Property, Plant, and Equipment — Reporting Discontinued Operations and Disclosure of Disposals of Components of an Entity (ASU 2014-08) As of January 1, 2015, we adopted ASU 2014-08. The amendments in this ASU modify the requirements for the reporting of discontinued operations. In order to qualify as a discontinued operation, the disposal of a component of an entity, a group of components, or a business of an entity must represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. The ASU further indicates that the timing for recording a discontinued operation is when one of the following occurs: the component, group of components, or business meets the criteria to be classified as held-for-sale; the component, group of components, or business is disposed of by sale; or the component, group of components, or business is disposed of other than by sale (for example abandonment or spinoff). In addition, the ASU also requires additional disclosure items about an entity’s discontinued operations. The amendments were applied prospectively solely to newly identified disposals that qualify as discontinued operations after the effective date. Items previously reported as discontinued operations maintain their classification based on the prior guidance. The adoption of this guidance did not have a material effect on our consolidated financial condition or results of operations. Transfers and Servicing — Repurchase-to-Maturity Transactions, Repurchase Financings and Disclosures (ASU 2014-11) As of January 1, 2015, we adopted ASU 2014-11. The amendments in this ASU change the accounting for repurchase-to-maturity transactions and repurchase financing transactions such that both will be reported as secured borrowings. In addition to the changes to how these transactions are reported, the ASU also includes new disclosure requirements. The amendments were applied to all transactions that fall under the guidance as of the date of adoption with a cumulative effect adjustment recorded on the date of initial adoption. The adoption of this guidance did not have a material effect on our consolidated financial condition or results of operations. Recently Issued Accounting Standards Revenue from Contracts with Customers (ASU 2014-09) and Revenue from Contracts with Customers — Deferral of the Effective Date (ASU 2015-14) In May 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09. The purpose of this guidance is to streamline and consolidate existing revenue recognition principles in GAAP and to converge revenue recognition principles with International Financial Reporting Standards (IFRS). The core principle of the amendments is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to receive in exchange for those goods or services. The amendments include a five step process for consideration of the main principle, guidance on the accounting treatment for costs associated with a contract, and disclosure requirements related to the revenue process. As originally issued, the amendments in ASU 2014-09 were to be effective for us beginning on January 1, 2017. However, in August 2015, the FASB issued ASU 2015-14, which deferred the effective date of the guidance for us until January 1, 2018, and permitted early adoption as of the original effective date in ASU 2014-09. The amendments to the revenue recognition principles can be applied on adoption either through a full retrospective application or on a modified basis with a cumulative effect adjustment on the date of initial adoption with certain practical expedients. Management is assessing the impact of the adoption of this guidance. Consolidation — Amendments to the Consolidation Analysis (ASU 2015-02) In February 2015, the FASB issued ASU 2015-02. The amendments in this update modify the requirements of consolidation with respect to entities that are or are similar in nature to limited partnerships or are variable interest entities (VIEs). For entities that are or are similar to limited partnerships, the guidance clarifies the evaluation of kick-out rights, removes the presumption that the general partner will consolidate and generally states that such entities will be presumed to be VIEs unless proven otherwise. For VIEs, the guidance modifies the analysis related to the evaluation of servicing fees, excludes servicing fees that are deemed commensurate with the level of service required from the determination of the primary beneficiary and clarifies certain considerations related to the consolidation analysis when performing a related party assessment. The amendments are effective for us on January 1, 2016, with early adoption permitted. The amendments can be applied either through a full retrospective application or on a modified retrospective basis with a cumulative effect adjustment on the date of initial adoption. Based on our preliminary assessment within our ongoing implementation efforts, we are not anticipating a material impact to our consolidated financial condition or results of operations upon adoption. Imputation of Interest — Simplifying the Presentation of Debt Issuance Costs (ASU 2015-03) and Imputation of Interest — Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements (ASU 2015-15) In April 2015, the FASB issued ASU 2015-03. The amendments in this update require that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Currently debt issuance costs are presented as a deferred charge and are therefore presented as an asset. The recognition and measurement requirements will not change as a result of this guidance. Additionally, in August 2015, the FASB issued ASU 2015-15 which codified comments made by the SEC that costs associated with revolving lines of credit may continue to be presented as an asset subsequent to the adoption of the guidance in ASU 2015-03. The amendments in ASU 2015-03 are effective for us on January 1, 2016, with early adoption permitted. The amendments must be applied with retrospective application, with each balance sheet period presented showing the impacts of applying the guidance. The guidance is not expected to have a material impact to our consolidated financial condition or results of operations.

Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies

Ally Financial Inc. (referred to herein as Ally, we, our, or us) is a leading, independent, diversified financial services firm. Founded in 1919, we are a leading financial services company with more than 95 years of experience providing a broad array of financial products and services, primarily to automotive dealers and retail customers. We operate as a financial holding company (FHC) and a bank holding company (BHC). Our banking subsidiary, Ally Bank, is an indirect, wholly-owned subsidiary of Ally Financial Inc. and a leading franchise in the growing direct (internet, telephone, mobile, and mail) banking market.

Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America (GAAP). Additionally, where applicable, the policies conform to the accounting and reporting guidelines prescribed by bank regulatory authorities. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and that affect income and expenses during the reporting period and related disclosures. In developing the estimates and assumptions, management uses all available evidence; however, actual results could differ because of uncertainties associated with estimating the amounts, timing, and likelihood of possible outcomes.

The Condensed Consolidated Financial Statements at September 30, 2015, and for the three months and nine months ended September 30, 2015, and 2014, are unaudited but reflect all adjustments that are, in management’s opinion, necessary for the fair presentation of the results for the interim periods presented. All such adjustments are of a normal recurring nature. These unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements (and the related notes) included in our Annual Report on Form 10-K for the year ended December 31, 2014, as filed on February 27, 2015, with the U.S. Securities and Exchange Commission (SEC).

Significant Accounting Policies

Income Taxes

In calculating the provision for interim income taxes, in accordance with Accounting Standards Codification (ASC) 740, Income Taxes, we apply an estimated annual effective tax rate to year-to-date ordinary income. At the end of each interim period, we estimate the effective tax rate expected to be applicable for the full fiscal year. This method differs from that described in Note 1 to the Consolidated Financial Statements in our 2014 Annual Report on Form 10-K, which describes our annual significant income tax accounting policy and related methodology.

Refer to Note 1 to the Consolidated Financial Statements in our 2014 Annual Report on Form 10-K regarding additional significant accounting policies.

Recently Adopted Accounting Standards

Receivables — Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure (ASU 2014-04)

As of January 1, 2015, we adopted ASU (Accounting Standards Update) 2014-04. The amendments in this ASU clarify the timing for which an entity should reclassify a loan that has been foreclosed or where an in substance repossession has occurred to real estate owned. The guidance requires a reclassification to occur when the entity obtains legal title upon completion of foreclosure or the borrower conveys all interest in the residential real estate property to the entity to satisfy the loan through completion of a deed in lieu of foreclosure or similar legal agreement. In addition, the ASU clarifies that redemption rights of the borrower should be ignored for purposes of determining whether legal title has transferred. We adopted the guidance utilizing a modified retrospective approach. The adoption of this guidance did not have a material effect on our consolidated financial condition or results of operations.

Presentation of Financial Statements and Property, Plant, and Equipment — Reporting Discontinued Operations and Disclosure of Disposals of Components of an Entity (ASU 2014-08)

As of January 1, 2015, we adopted ASU 2014-08. The amendments in this ASU modify the requirements for the reporting of discontinued operations. In order to qualify as a discontinued operation, the disposal of a component of an entity, a group of components, or a business of an entity must represent a strategic shift that has (or will have) a major effect on an entity’s operations and financial results. The ASU further indicates that the timing for recording a discontinued operation is when one of the following occurs: the component, group of components, or business meets the criteria to be classified as held-for-sale; the component, group of components, or business is disposed of by sale; or the component, group of components, or business is disposed of other than by sale (for example abandonment or spinoff). In addition, the ASU also requires additional disclosure items about an entity’s discontinued operations. The amendments were applied prospectively solely to newly identified disposals that qualify as discontinued operations after the effective date. Items previously reported as discontinued operations maintain their classification based on the prior guidance. The adoption of this guidance did not have a material effect on our consolidated financial condition or results of operations.

Transfers and Servicing — Repurchase-to-Maturity Transactions, Repurchase Financings and Disclosures (ASU 2014-11)

As of January 1, 2015, we adopted ASU 2014-11. The amendments in this ASU change the accounting for repurchase-to-maturity transactions and repurchase financing transactions such that both will be reported as secured borrowings. In addition to the changes to how these transactions are reported, the ASU also includes new disclosure requirements. The amendments were applied to all transactions that fall under the guidance as of the date of adoption with a cumulative effect adjustment recorded on the date of initial adoption. The adoption of this guidance did not have a material effect on our consolidated financial condition or results of operations.

Recently Issued Accounting Standards

Revenue from Contracts with Customers (ASU 2014-09) and Revenue from Contracts with Customers — Deferral of the Effective Date (ASU 2015-14)

In May 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09. The purpose of this guidance is to streamline and consolidate existing revenue recognition principles in GAAP and to converge revenue recognition principles with International Financial Reporting Standards (IFRS). The core principle of the amendments is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to receive in exchange for those goods or services. The amendments include a five step process for consideration of the main principle, guidance on the accounting treatment for costs associated with a contract, and disclosure requirements related to the revenue process. As originally issued, the amendments in ASU 2014-09 were to be effective for us beginning on January 1, 2017. However, in August 2015, the FASB issued ASU 2015-14, which deferred the effective date of the guidance for us until January 1, 2018, and permitted early adoption as of the original effective date in ASU 2014-09. The amendments to the revenue recognition principles can be applied on adoption either through a full retrospective application or on a modified basis with a cumulative effect adjustment on the date of initial adoption with certain practical expedients. Management is assessing the impact of the adoption of this guidance.

Consolidation — Amendments to the Consolidation Analysis (ASU 2015-02)

In February 2015, the FASB issued ASU 2015-02. The amendments in this update modify the requirements of consolidation with respect to entities that are or are similar in nature to limited partnerships or are variable interest entities (VIEs). For entities that are or are similar to limited partnerships, the guidance clarifies the evaluation of kick-out rights, removes the presumption that the general partner will consolidate and generally states that such entities will be presumed to be VIEs unless proven otherwise. For VIEs, the guidance modifies the analysis related to the evaluation of servicing fees, excludes servicing fees that are deemed commensurate with the level of service required from the determination of the primary beneficiary and clarifies certain considerations related to the consolidation analysis when performing a related party assessment. The amendments are effective for us on January 1, 2016, with early adoption permitted. The amendments can be applied either through a full retrospective application or on a modified retrospective basis with a cumulative effect adjustment on the date of initial adoption. Based on our preliminary assessment within our ongoing implementation efforts, we are not anticipating a material impact to our consolidated financial condition or results of operations upon adoption.

Imputation of Interest — Simplifying the Presentation of Debt Issuance Costs (ASU 2015-03) and Imputation of Interest — Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements (ASU 2015-15)

In April 2015, the FASB issued ASU 2015-03. The amendments in this update require that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. Currently debt issuance costs are presented as a deferred charge and are therefore presented as an asset. The recognition and measurement requirements will not change as a result of this guidance. Additionally, in August 2015, the FASB issued ASU 2015-15 which codified comments made by the SEC that costs associated with revolving lines of credit may continue to be presented as an asset subsequent to the adoption of the guidance in ASU 2015-03. The amendments in ASU 2015-03 are effective for us on January 1, 2016, with early adoption permitted. The amendments must be applied with retrospective application, with each balance sheet period presented showing the impacts of applying the guidance. The guidance is not expected to have a material impact to our consolidated financial condition or results of operations.