Subsequent Events	3 Months Ended
Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Declaration of Quarterly Dividend Payments On April 1, 2015, the Ally Board of Directors declared quarterly dividend payments on certain outstanding preferred stock. This included a cash dividend of $17.11 per share, or a total of $22 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 to shareholders of record as of May 1, 2015 and are payable on May 15, 2015. Redemption of Fixed Rate Cumulative Perpetual Preferred Stock, Series G On April 10, 2015, we redeemed 1,288,300 shares of our outstanding Fixed Rate Cumulative Perpetual Preferred Stock, Series G, with an aggregate liquidation preference of approximately $1.3 billion. Following this transaction, 1,288,301 shares of our Series G Preferred Stock remain outstanding, with a carrying value of approximately $117 million. Tender Offer to Repurchase Fixed Rate/Floating Rate Perpetual Preferred Stock, Series A On April 23, 2015, we announced a tender offer to purchase up to 13 million shares of our outstanding Fixed Rate/Floating Rate Perpetual Preferred Stock, Series A, for $26.65 per Series A share (Offer Price). The Offer Price represents the total consideration payable per share including accrued and unpaid dividends. Mitsubishi Agreement On April 27, 2015, we announced that Mitsubishi Motors North America, Inc. (MMNA) has selected Ally as the preferred provider of leasing and financing in the United States, replacing MMNA's captive finance company, Mitsubishi Motors Credit of America, Inc. (MMCA). We intend to purchase the existing consumer portfolio from MMCA, which includes approximately $750 million in retail financings and leases as of January 31, 2015. In addition, we will begin to provide commercial financing to dealerships with approximately $300 million in floorplan assets that are currently financing through MMCA.

Subsequent Events

Declaration of Quarterly Dividend Payments

On April 1, 2015, the Ally Board of Directors declared quarterly dividend payments on certain outstanding preferred stock. This included a cash dividend of $17.11 per share, or a total of $22 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 to shareholders of record as of May 1, 2015 and are payable on May 15, 2015.

Redemption of Fixed Rate Cumulative Perpetual Preferred Stock, Series G

On April 10, 2015, we redeemed 1,288,300 shares of our outstanding Fixed Rate Cumulative Perpetual Preferred Stock, Series G, with an aggregate liquidation preference of approximately $1.3 billion. Following this transaction, 1,288,301 shares of our Series G Preferred Stock remain outstanding, with a carrying value of approximately $117 million.

Tender Offer to Repurchase Fixed Rate/Floating Rate Perpetual Preferred Stock, Series A

On April 23, 2015, we announced a tender offer to purchase up to 13 million shares of our outstanding Fixed Rate/Floating Rate Perpetual Preferred Stock, Series A, for $26.65 per Series A share (Offer Price). The Offer Price represents the total consideration payable per share including accrued and unpaid dividends.

Mitsubishi Agreement

On April 27, 2015, we announced that Mitsubishi Motors North America, Inc. (MMNA) has selected Ally as the preferred provider of leasing and financing in the United States, replacing MMNA's captive finance company, Mitsubishi Motors Credit of America, Inc. (MMCA). We intend to purchase the existing consumer portfolio from MMCA, which includes approximately $750 million in retail financings and leases as of January 31, 2015. In addition, we will begin to provide commercial financing to dealerships with approximately $300 million in floorplan assets that are currently financing through MMCA.