Represents the amount related to loan servicing fee expense as related party expense.

No definition available.

Name:	ajx_RelatedPartyLoanServicingFeeExpense
Namespace Prefix:	ajx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount related to management fee expense as related party expense.

+ References

No definition available.

+ Details

Name:	ajx_RelatedPartyManagementFeeExpense
Namespace Prefix:	ajx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123605549&loc=d3e21493-158490

+ Details

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

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
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+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_IncomeStatementLocationAxis=ajx_NetInterestIncomeAfterProvisionForCreditBenefitlossesMember
Namespace Prefix:
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Balance Type:
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- Details

Name:	srt_CounterpartyNameAxis=ajx_ThetisAssetManagementLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=ajx_ManagementFeeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=ajx_IncomefrominvestmentsinaffiliateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_GregoryFundingLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=ajx_LoanServicingFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_NonConsolidatedJointVenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_OtherIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_AsAjaxELlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_GaeaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_LegacyEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_AjaxMortgageLoanTrust2021CMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=ajx_GreatAjaxFinancialServicesLLCMember
Namespace Prefix:
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Related Party Transactions - Schedule Statement of Income of Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Related Party Transaction [Line Items]
Related party expense – management fee	$ 2,292	$ 2,264	$ 6,835	$ 6,206
Related party expense – loan servicing fees	1,743	1,848	5,275	5,798
Loss on sale of mortgage loans			0	(705)
Net interest income after the impact of changes in the net present value of expected credit losses
Related Party Transaction [Line Items]
Amount of transaction	9,896	6,536	24,835	16,386
Thetis Asset Management LLC
Related Party Transaction [Line Items]
Related party expense – management fee		2,300		6,200
Thetis Asset Management LLC \| Management fee
Related Party Transaction [Line Items]
Related party expense – management fee	2,289	2,264	6,826	6,206
Thetis Asset Management LLC \| Income/(loss) from investments in affiliates
Related Party Transaction [Line Items]
Amount of transaction	132	75	583	(364)
Servicer \| Related party expense – loan servicing fees
Related Party Transaction [Line Items]
Related party expense – loan servicing fees	1,743	1,848	5,275	5,798
Various non-consolidated joint ventures \| Other income
Related Party Transaction [Line Items]
Amount of transaction	201	145	201	145
AS Ajax E LLC \| Income/(loss) from investments in affiliates
Related Party Transaction [Line Items]
Amount of transaction	11	9	27	25
Gaea \| Income/(loss) from investments in affiliates
Related Party Transaction [Line Items]
Amount of transaction	(28)	14	32	74
Gaea \| Interest income
Related Party Transaction [Line Items]
Amount of transaction	74	0	203	0
Gaea \| Other income
Related Party Transaction [Line Items]
Loss on sale of mortgage loans			0	(705)
Investment in Loan pool LLCs \| Income/(loss) from investments in affiliates
Related Party Transaction [Line Items]
Amount of transaction	(16)	(46)	(37)	10
2021-C \| Other income
Related Party Transaction [Line Items]
Amount of transaction			122	0
Servicer \| Income/(loss) from investments in affiliates
Related Party Transaction [Line Items]
Amount of transaction	$ (37)	$ (116)	$ (92)	$ (320)