Equity - Narrative (Details)	3 Months Ended			12 Months Ended
	Mar. 31, 2022 USD ($) entity loan $ / shares shares	Mar. 31, 2021 USD ($) shares	Jun. 30, 2020 $ / shares shares	Dec. 31, 2021 entity $ / shares shares	Oct. 01, 2021 shares	Feb. 28, 2020 USD ($)
Class of Stock [Line Items]
Common stock, shares outstanding (in shares)	23,194,566			23,146,775
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.01			$ 0.01
Common stock, shares authorized (in shares)	125,000,000			125,000,000
Preferred stock, par value per share (in dollars per share) | $ / shares	$ 0.01			$ 0.01
Warrant term			5 years
Class of warrant or right, outstanding (in shares)	6,500,000	6,500,000	6,500,000
Investment warrants, exercise price (in dollars per share) | $ / shares			$ 10.00
Preferred stock, shares authorized (in shares)	25,000,000			25,000,000
Common stock authorized | $						$ 25,000,000
Treasury stock (in shares)	(157,776)			(147,370)
Sale of common stock pursuant to dividend reinvestment plan | $	$ 115,000	$ 47,000
Common stock, shares issued (in shares)	23,194,566			23,146,775
Number of non controlling interest subsidiaries | entity	3			3
Number of remaining loans | loan	22
Open market purchases
Class of Stock [Line Items]
Treasury stock (in shares)	(49,684)			(49,684)	(1,220)
AS Ajax E II LLC
Class of Stock [Line Items]
Ownership percentage by parent	53.10%			53.10%
2017-D
Class of Stock [Line Items]
Ownership percentage by third parties	50.00%			50.00%
Ownership percentage by parent	50.00%			50.00%
Great Ajax II REIT
Class of Stock [Line Items]
Ownership percentage by parent	99.90%			99.90%
Common stock
Class of Stock [Line Items]
Issuance of shares under dividend reinvestment plan (in shares)	9,739	4,228
Sale of common stock pursuant to dividend reinvestment plan | $	$ 100,000	$ 47,000
Thetis Asset Management LLC
Class of Stock [Line Items]
Treasury stock (in shares)	(108,092)			(97,686)
AS Ajax E II LLC | Third party
Class of Stock [Line Items]
Ownership percentage by third parties	46.90%
Great Ajax II REIT | Third party
Class of Stock [Line Items]
Ownership percentage by third parties	0.10%			0.10%
2018-C | Third party
Class of Stock [Line Items]
Ownership percentage by third parties		37.00%
2018-C | Great Ajax Corp
Class of Stock [Line Items]
Ownership percentage by parent	100.00%			100.00%
Third party | 2017-D
Class of Stock [Line Items]
Ownership percentage by third parties	50.00%
7.25% Series A preferred stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	2,307,400		2,307,400	2,307,400
Preferred stock, fixed-to-floating rate cumulative redeemable	7.25%		7.25%	7.25%
Preferred stock, shares outstanding (in shares)	2,307,400			2,307,400
Preferred stock - Series B shares
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	2,892,600		2,892,600	2,892,600
Preferred stock, fixed-to-floating rate cumulative redeemable	5.00%		5.00%	5.00%
Preferred stock, shares outstanding (in shares)	2,892,600			2,892,600
At-the-Market Program
Class of Stock [Line Items]
Common stock authorized | $	$ 100,000,000
Common stock, shares issued (in shares)	0	0