Affiliates - Narrative (Details) $ in Thousands				12 Months Ended
	Nov. 22, 2019 USD ($) shares	May 29, 2018 USD ($) warrant shares	Jan. 26, 2018 USD ($) warrant shares	Dec. 31, 2019 USD ($) counterparty transaction	Dec. 31, 2018
Great Ajax FS LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage				8.00%
Number of transactions | transaction				2
Percentage of equity interest at closing date		3.10%	4.90%
Number of warrants | warrant		3	3
Percentage of warrants exercisable		1.55%	2.45%
Cash payment in business acquisition		$ 700	$ 1,100
Number of shares (in shares) | shares		29,063	45,938
Common stock value		$ 400	$ 600
Legacy entities
Schedule of Equity Method Investments [Line Items]
Ownership percentage				40.43%
Cash payment in business acquisition				$ 1,000
Number of entities | counterparty				3
Securitization Trust, 2017-D
Schedule of Equity Method Investments [Line Items]
Percentage of Interests in Trust Certificates Sold to Third Parties					5000.00%
Great Ajax FS LLC
Schedule of Equity Method Investments [Line Items]
Amount prior to equity method investment				$ 0
Thetis
Schedule of Equity Method Investments [Line Items]
Ownership percentage				19.80%
Ajax E Master Trust | AS Ajax E LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest in real estate trust, percentage				5.00%
AS Ajax E LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage				16.50%	16.50%
Gaea
Schedule of Equity Method Investments [Line Items]
Proceeds from Issuance of Private Placement	$ 66,300
Private placement share issuance | shares	4,419,641
Ownership percentage				23.20%
Gaea | Third Party
Schedule of Equity Method Investments [Line Items]
Ownership percentage by noncontrolling owners				76.80%