Subsequent Events	12 Months Ended
Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Completion of Disposition of Assets We previously announced that we had reached an agreement to sell our 40% interest in a motor vehicle finance joint venture in China (JV Interest) pursuant to a Share Transfer Agreement, dated November 21, 2012, as amended, between Ally, GMF, and GMAC UK PLC (GMAC UK) (Share Transfer Agreement). GMF and GMAC UK are each wholly-owned subsidiaries of General Motors Co. During the fourth quarter of 2012, the JV interest was classified as a discontinued operation. On January 2, 2015, we completed the sale of the JV Interest, receiving approximately $1.0 billion in total consideration at closing, which is subject to certain post-closing adjustments. As a result of completing this sale, we recorded an after-tax gain of $395 million in the first quarter of 2015. Declaration of Quarterly Dividend Payments On January 13, 2015, the Ally Board of Directors declared quarterly dividend payments on certain outstanding preferred stock. This included 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 were paid on February 17, 2015. Management Change On February 2, 2015, Ally announced that Jeffrey J. Brown has been named Chief Executive Officer, effective immediately. Brown, who most recently served as President and Chief Executive Officer of Ally’s Dealer Financial Services business, has also joined Ally’s Board of Directors. Brown succeeds Michael A. Carpenter, who is retiring as Chief Executive Officer and from the Board of Directors. Notes Offering On February 10, 2015, we completed securities offerings of $600 million and $650 million in aggregate principal amount of Ally senior guaranteed notes due February 2018 and February 2022, respectively. The notes bear interest at per annum rates of 3.25% and 4.125%, respectively. Tender Offer On February 10, 2015, concurrently with the notes offerings disclosed above, we announced a tender offer to repurchase $750 million of our 8.00% Senior Guaranteed Notes due 2020 and our 7.50% Senior Guaranteed Notes due 2020 (2020 Notes); and $150 million of our 8.00% Senior Notes due 2031. Following the early tender deadline on February 24, 2015, we upsized the tender amount on our 2020 Notes to $800 million and accepted $247 million of our 8.00% Senior Guaranteed Notes due 2020, $553 million of our 7.50% Senior Guaranteed Notes due 2020, and $150 million of our 8.00% Senior Notes due 2031. We expect to record a loss on extinguishment of debt of approximately $195 million in the first quarter of 2015 related to this transaction.

Subsequent Events

Completion of Disposition of Assets

We previously announced that we had reached an agreement to sell our 40% interest in a motor vehicle finance joint venture in China (JV Interest) pursuant to a Share Transfer Agreement, dated November 21, 2012, as amended, between Ally, GMF, and GMAC UK PLC (GMAC UK) (Share Transfer Agreement). GMF and GMAC UK are each wholly-owned subsidiaries of General Motors Co. During the fourth quarter of 2012, the JV interest was classified as a discontinued operation.

On January 2, 2015, we completed the sale of the JV Interest, receiving approximately $1.0 billion in total consideration at closing, which is subject to certain post-closing adjustments. As a result of completing this sale, we recorded an after-tax gain of $395 million in the first quarter of 2015.

Declaration of Quarterly Dividend Payments

On January 13, 2015, the Ally Board of Directors declared quarterly dividend payments on certain outstanding preferred stock. This included 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 were paid on February 17, 2015.

Management Change

On February 2, 2015, Ally announced that Jeffrey J. Brown has been named Chief Executive Officer, effective immediately. Brown, who most recently served as President and Chief Executive Officer of Ally’s Dealer Financial Services business, has also joined Ally’s Board of Directors. Brown succeeds Michael A. Carpenter, who is retiring as Chief Executive Officer and from the Board of Directors.

Notes Offering

On February 10, 2015, we completed securities offerings of $600 million and $650 million in aggregate principal amount of Ally senior guaranteed notes due February 2018 and February 2022, respectively. The notes bear interest at per annum rates of 3.25% and 4.125%, respectively.

Tender Offer

On February 10, 2015, concurrently with the notes offerings disclosed above, we announced a tender offer to repurchase $750 million of our 8.00% Senior Guaranteed Notes due 2020 and our 7.50% Senior Guaranteed Notes due 2020 (2020 Notes); and $150 million of our 8.00% Senior Notes due 2031. Following the early tender deadline on February 24, 2015, we upsized the tender amount on our 2020 Notes to $800 million and accepted $247 million of our 8.00% Senior Guaranteed Notes due 2020, $553 million of our 7.50% Senior Guaranteed Notes due 2020, and $150 million of our 8.00% Senior Notes due 2031. We expect to record a loss on extinguishment of debt of approximately $195 million in the first quarter of 2015 related to this transaction.