Mortgage Loans - Schedule of Carrying Value of Mortgage Loans (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans | loan		6,184	7,111
Carrying value	[1],[2]	$ 1,151,469	$ 1,310,873
Unpaid principal balance		$ 1,268,126	$ 1,481,719
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans | loan		3,449	3,929
Carrying value		$ 676,144	$ 757,276
Unpaid principal balance		$ 735,307	$ 848,551
30
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans | loan		851	1,006
Carrying value		$ 146,208	$ 167,286
Unpaid principal balance		$ 158,363	$ 185,742
60
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans | loan		568	711
Carrying value		$ 93,806	$ 123,078
Unpaid principal balance		$ 102,661	$ 136,586
90
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans | loan		1,173	1,188
Carrying value		$ 197,014	$ 200,419
Unpaid principal balance		$ 224,078	$ 231,063
Foreclosure
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans | loan		143	277
Carrying value		$ 38,297	$ 62,814
Unpaid principal balance		$ 47,717	$ 79,777

[1] As of December 31, 2019, balances for Mortgage loans, net includes $341.8 million and Secured borrowings, net of deferred costs includes $284.8 million from the 50.0% and 63.0% owned joint ventures, respectively. As of December 31, 2018, balances for Mortgage loans, net include $377.0 million and Secured borrowings, net of deferred costs includes $231.9 million from the 50.0% and 63.0% owned joint ventures, all of which the Company consolidates under U.S. Generally Accepted Accounting Principles ("U.S. GAAP").

[2] Mortgage loans, net include $908.6 million and $897.8 million of loans at December 31, 2019 and December 31, 2018, respectively, transferred to securitization trusts that are variable interest entities (“VIEs”); these loans can only be used to settle obligations of the VIEs. Secured borrowings consist of notes issued by VIEs that can only be settled with the assets and cash flows of the VIEs. The creditors do not have recourse to the primary beneficiary (Great Ajax Corp.). See Note 9 — Debt. Mortgage loans, net include $2.0 million and $1.2 million of allowance for loan losses at December 31, 2019 and December 31, 2018, respectively.