Subsequent Events	9 Months Ended
Sep. 30, 2012
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Declaration of Quarterly Dividend Payments On October 4, 2012, the Ally Board of Directors declared quarterly dividend payments on certain outstanding preferred stock. This included a cash dividend of $1.125 per share, or a total of $134 million, on Fixed Rate Cumulative Mandatorily Convertible Preferred Stock, Series F-2; a cash dividend of $17.50 per share, or a total of $45 million, on Fixed Rate Cumulative Perpetual Preferred Stock, Series G; and a cash dividend of $0.53 per share, or a total of $22 million, on Fixed Rate/Floating Rate Perpetual Preferred Stock, Series A. The dividends are payable on November 15, 2012. Defined Benefit Pension Plan Actions GMAC Mortgage Group LLC, our wholly owned subsidiary, sponsors a defined benefit pension plan (the Pension Plan) for which the accrual of additional benefits were previously frozen. The Pension Plan primarily covers former employees of certain discontinued or non-core businesses of our Mortgage and Insurance operations. In October 2012, we entered into an agreement under which the Pension Plan purchased a group annuity contract from a third-party insurance company that requires the insurance company to pay and administer all future annuity payments to the current retiree population of the Pension Plan (retired as of September 1, 2012) beginning on January 1, 2013. Additionally, during the fourth quarter the Pension Plan is commencing a program to offer voluntary lump-sum distributions to terminated employees with vested benefits in the Pension Plan. We expect that all lump-sum distributions from the Pension Plan will be completed by December 31, 2012. In connection with these combined actions we expect to record a settlement loss of approximately $90 million to $120 million during the fourth quarter of 2012 due primarily to the immediate recognition of amounts currently classified as the defined benefit pension plan net actuarial losses component of Accumulated other comprehensive income. Accordingly, we do not expect the fourth quarter settlement loss to result in a material change to consolidated total equity. The ultimate amount of the settlement loss could differ from currently estimated amounts due to several factors including, for example, the lump-sum distribution election rate, a change in the discount rate, or significant gains or losses in trust assets prior to the date of accounting recognition. Mexican Insurance Business Sale Agreement On October 18, 2012, we announced that we had reached an agreement to sell our Mexican insurance business, ABA Seguros, to the ACE Group. The purchase price of $865 million in cash is at a premium to our book value. The book value of ABA Seguros was $429 million at September 30, 2012. Any gain on sale will be determined and recognized when the transaction closes. Completion of the transaction is subject to regulatory approvals and the satisfaction of other customary closing conditions. The transaction is expected to close during the first half of next year. Canadian Auto Finance Operation Sale Agreement On October 23, 2012, we announced that we had reached an agreement to sell our Canadian auto finance operation, Ally Credit Canada Limited, and ResMor Trust to Royal Bank of Canada. Based on the third quarter total equity of the Canadian auto finance operation, Ally would receive approximately $4.1 billion in proceeds, which would be a premium to our book value. The book value of our Canadian auto finance operation was $3.5 billion at September 30, 2012. Any gain on sale will be determined and recognized when the transaction closes. The transaction is subject to regulatory approval and the satisfaction of other customary closing conditions. The transaction is expected to close in the first quarter of 2013.

Subsequent Events

Declaration of Quarterly Dividend Payments

On October 4, 2012, the Ally Board of Directors declared quarterly dividend payments on certain outstanding preferred stock. This included a cash dividend of $1.125 per share, or a total of $134 million, on Fixed Rate Cumulative Mandatorily Convertible Preferred Stock, Series F-2; a cash dividend of $17.50 per share, or a total of $45 million, on Fixed Rate Cumulative Perpetual Preferred Stock, Series G; and a cash dividend of $0.53 per share, or a total of $22 million, on Fixed Rate/Floating Rate Perpetual Preferred Stock, Series A. The dividends are payable on November 15, 2012.

Defined Benefit Pension Plan Actions

GMAC Mortgage Group LLC, our wholly owned subsidiary, sponsors a defined benefit pension plan (the Pension Plan) for which the accrual of additional benefits were previously frozen. The Pension Plan primarily covers former employees of certain discontinued or non-core businesses of our Mortgage and Insurance operations. In October 2012, we entered into an agreement under which the Pension Plan purchased a group annuity contract from a third-party insurance company that requires the insurance company to pay and administer all future annuity payments to the current retiree population of the Pension Plan (retired as of September 1, 2012) beginning on January 1, 2013. Additionally, during the fourth quarter the Pension Plan is commencing a program to offer voluntary lump-sum distributions to terminated employees with vested benefits in the Pension Plan. We expect that all lump-sum distributions from the Pension Plan will be completed by December 31, 2012. In connection with these combined actions we expect to record a settlement loss of approximately $90 million to $120 million during the fourth quarter of 2012 due primarily to the immediate recognition of amounts currently classified as the defined benefit pension plan net actuarial losses component of Accumulated other comprehensive income. Accordingly, we do not expect the fourth quarter settlement loss to result in a material change to consolidated total equity. The ultimate amount of the settlement loss could differ from currently estimated amounts due to several factors including, for example, the lump-sum distribution election rate, a change in the discount rate, or significant gains or losses in trust assets prior to the date of accounting recognition.

Mexican Insurance Business Sale Agreement

On October 18, 2012, we announced that we had reached an agreement to sell our Mexican insurance business, ABA Seguros, to the ACE Group. The purchase price of $865 million in cash is at a premium to our book value. The book value of ABA Seguros was $429 million at September 30, 2012. Any gain on sale will be determined and recognized when the transaction closes. Completion of the transaction is subject to regulatory approvals and the satisfaction of other customary closing conditions. The transaction is expected to close during the first half of next year.

Canadian Auto Finance Operation Sale Agreement

On October 23, 2012, we announced that we had reached an agreement to sell our Canadian auto finance operation, Ally Credit Canada Limited, and ResMor Trust to Royal Bank of Canada. Based on the third quarter total equity of the Canadian auto finance operation, Ally would receive approximately $4.1 billion in proceeds, which would be a premium to our book value. The book value of our Canadian auto finance operation was $3.5 billion at September 30, 2012. Any gain on sale will be determined and recognized when the transaction closes. The transaction is subject to regulatory approval and the satisfaction of other customary closing conditions. The transaction is expected to close in the first quarter of 2013.