Held for investment mortgage finance receivables interest only mortgage loans.

No definition available.

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

- Details

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate interest and fee income generated by: (1) loans the Entity has positive intent and ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (a) industrial and agricultural; (b) real estate; and (c) real estate construction loans; (d) trade financing; (e) lease financing; (f) home equity lines-of-credit; (g) automobile and other vehicle loans; and (h) credit card and other revolving-type loans and (2) loans and leases held-for-sale which may include mortgage loans, direct financing, and sales-type leases.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.1)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 9

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

+ Details

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

- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Glossary Loan

-URI http://asc.fasb.org/extlink&oid=6517073

+ Details

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

- Definition

Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533

+ Details

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

Finance Receivables And Loans, Net (Schedule of Accounts, Notes, Loans and Financing Receivables) (Details) (USD $)	3 Months Ended																	3 Months Ended				3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Consumer Loans Auto Financing Receivable [Member]	Dec. 31, 2013 Consumer Loans Auto Financing Receivable [Member]	Mar. 31, 2014 Residential Mortgage [Member]	Dec. 31, 2013 Residential Mortgage [Member]	Mar. 31, 2014 Commercial Loan [Member]	Dec. 31, 2013 Commercial Loan [Member]	Mar. 31, 2014 Commercial And Industrial Automobile [Member]	Dec. 31, 2013 Commercial And Industrial Automobile [Member]	Mar. 31, 2014 Commercial And Industrial Other [Member]	Dec. 31, 2013 Commercial And Industrial Other [Member]	Mar. 31, 2014 Commercial Real Estate Automobile [Member]	Dec. 31, 2013 Commercial Real Estate Automobile [Member]	Mar. 31, 2014 loans held-for-investment [Member]	Dec. 31, 2013 loans held-for-investment [Member]	Mar. 31, 2014 Designated as Hedging Instrument [Member] Gain (Loss) Recognized in Earnings on Hedged Item [Member] Interest Rate Contract [Member]	Mar. 31, 2013 Designated as Hedging Instrument [Member] Gain (Loss) Recognized in Earnings on Hedged Item [Member] Interest Rate Contract [Member]	Mar. 31, 2014 Fair Value Option Election, Fair Value [Member]	Dec. 31, 2013 Fair Value Option Election, Fair Value [Member]	Mar. 31, 2014 Fair Value Option Election, Fair Value [Member] Designated as Hedging Instrument [Member] Gain (Loss) Recognized in Earnings on Hedged Item [Member] Interest Rate Contract [Member]	Dec. 31, 2013 Fair Value Option Election, Fair Value [Member] Designated as Hedging Instrument [Member] Gain (Loss) Recognized in Earnings on Hedged Item [Member] Interest Rate Contract [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance receivables and loans, net	$ 99,624,000,000	$ 99,123,000,000	$ 100,328,000,000	$ 56,775,000,000	$ 56,417,000,000	$ 8,138,000,000	$ 8,444,000,000	$ 34,711,000,000	$ 35,467,000,000	$ 30,062,000,000	$ 30,948,000,000	$ 1,727,000,000	$ 1,664,000,000	$ 2,922,000,000	$ 2,855,000,000					$ 99,624,000,000	$ 100,328,000,000
Interest and Fee Income, Loans and Leases	1,107,000,000	1,135,000,000																11,000,000	0			12,000,000	1,000,000
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	1,400,000,000		1,500,000,000
Loans Receivable, Fair Value Disclosure	12,000,000		1,000,000			1,000,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums																$ 504,000,000	$ 595,000,000