Interest in Joint Venture

No definition available.

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Namespace Prefix:	ally_
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- Definition

Tender offer to repurchase

+ References

No definition available.

+ Details

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Namespace Prefix:	ally_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Upsized tender offer to repurchase

+ References

No definition available.

+ Details

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Namespace Prefix:	ally_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of paid and unpaid preferred stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) on sale or disposal of an equity method investment.

+ References

No definition available.

+ Details

Name:	us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount per share used to calculated dividend payments on preferred stock.

+ References

No definition available.

+ Details

Name:	us-gaap_PreferredStockDividendRatePerDollarAmount
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Subsequent Events (Details) (USD $)	12 Months Ended			3 Months Ended
Subsequent Events (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015
Subsequent Event [Line Items]
Gain (loss) on extinguishment of debt	$ (202,000,000)	$ (59,000,000)	$ (148,000,000)
2020 [Member] \| 7.50% Senior Guaranteed Notes due 2020 [Member] [Member]
Subsequent Event [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate				7.50%
Automotive finance operations [Member]
Subsequent Event [Line Items]
Interest in Joint Venture	40.00%
Subsequent Event [Member]
Subsequent Event [Line Items]
Proceeds from Sale of Equity Method Investments				1,000,000,000
Equity Method Investment, Realized Gain (Loss) on Disposal				395,000,000
Gain (loss) on extinguishment of debt				195,000,000
Subsequent Event [Member] \| February 2018 [Member]
Subsequent Event [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Amount				600,000,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate				3.25%
Subsequent Event [Member] \| 2031 [Member]
Subsequent Event [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate				8.00%
Tender offer to repurchase				150,000,000
Debt Instrument, Repurchase Amount				150,000,000
Subsequent Event [Member] \| February 2022 [Member]
Subsequent Event [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Amount				650,000,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate				4.125%
Subsequent Event [Member] \| 2020 [Member]
Subsequent Event [Line Items]
Upsized tender offer to repurchase				800,000,000
Tender offer to repurchase				750,000,000
Subsequent Event [Member] \| 2020 [Member] \| 8.00% Senior Guaranteed Notes due 2020 [Member]
Subsequent Event [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate				8.00%
Debt Instrument, Repurchase Amount				247,000,000
Subsequent Event [Member] \| 2020 [Member] \| 7.50% Senior Guaranteed Notes due 2020 [Member] [Member]
Subsequent Event [Line Items]
Debt Instrument, Repurchase Amount				553,000,000
Subsequent Event [Member] \| Series G Preferred Stock [Member]
Subsequent Event [Line Items]
Cash dividend per share				$ 17.50
Dividends, Preferred Stock				45,000,000
Subsequent Event [Member] \| Series A Preferred Stock [Member]
Subsequent Event [Line Items]
Cash dividend per share				$ 0.53
Dividends, Preferred Stock				$ 22,000,000