Mortgage Loans - Schedule of loan basis by year of origination (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Mortgage Loans [Line Items]
Year one	$ 0	$ 4,242
Year two	749	10,946
Year three	9,293	10,300
Year four	9,618	5,133
Year five	5,120	4,386
Year six	4,448	2,970
Prior years, range 1	103,680	99,834
Prior years range 2	677,838	689,731
Prior years range 3	252,730	252,892
Financing receivable, before allowance for credit loss	1,063,476	1,080,434
Mortgage Loans Held For Sale
Mortgage Loans [Line Items]
Year one		0
Year two		0
Year three		204
Year four		0
Year five		0
Year six		0
Prior years, range 1		4,267
Prior years range 2		15,893
Prior years range 3		9,208
Financing receivable, before allowance for credit loss		29,572
GAOP 7f7 Greater Than 50
Mortgage Loans [Line Items]
Year one	0
Year two	282
Year three	7,245
Year four	5,991
Year five	1,429
Year six	2,064
Prior years, range 1	28,203
Prior years range 2	173,328
Prior years range 3	66,688
Financing receivable, before allowance for credit loss	285,230
GAOP 7f7 Less Than 50
Mortgage Loans [Line Items]
Year one	0
Year two	0
Year three	0
Year four	134
Year five	0
Year six	147
Prior years, range 1	4,829
Prior years range 2	44,042
Prior years range 3	14,149
Financing receivable, before allowance for credit loss	63,301
GAOP - 6f6 and below
Mortgage Loans [Line Items]
Year one	0
Year two	467
Year three	1,293
Year four	2,633
Year five	2,863
Year six	1,592
Prior years, range 1	22,945
Prior years range 2	137,594
Prior years range 3	52,365
Financing receivable, before allowance for credit loss	221,752
Great Ajax II REIT 7f7 Greater Than 50
Mortgage Loans [Line Items]
Year one	0
Year two	0
Year three	755
Year four	641
Year five	813
Year six	458
Prior years, range 1	36,624
Prior years range 2	262,077
Prior years range 3	94,594
Financing receivable, before allowance for credit loss	395,962
Great Ajax II REIT 7f7 Less Than 50
Mortgage Loans [Line Items]
Year one	0
Year two	0
Year three	0
Year four	219
Year five	15
Year six	45
Prior years, range 1	5,096
Prior years range 2	38,407
Prior years range 3	13,278
Financing receivable, before allowance for credit loss	57,060
Great Ajax II REIT - 6f6 and below
Mortgage Loans [Line Items]
Year one	0
Year two	0
Year three	0
Year four	0
Year five	0
Year six	142
Prior years, range 1	5,983
Prior years range 2	22,390
Prior years range 3	11,656
Financing receivable, before allowance for credit loss	$ 40,171
Great Ajax II REIT
Mortgage Loans [Line Items]
Year one		0
Year two		764
Year three		181
Year four		698
Year five		328
Year six		1,730
Prior years, range 1		46,041
Prior years range 2		339,759
Prior years range 3		125,095
Financing receivable, before allowance for credit loss		514,596
2021-B
Mortgage Loans [Line Items]
Year one		0
Year two		0
Year three		589
Year four		0
Year five		2,353
Year six		443
Prior years, range 1		28,541
Prior years range 2		159,318
Prior years range 3		50,948
Financing receivable, before allowance for credit loss		242,192
2019-C
Mortgage Loans [Line Items]
Year one		0
Year two		0
Year three		0
Year four		0
Year five		265
Year six		0
Prior years, range 1		9,020
Prior years range 2		96,995
Prior years range 3		39,801
Financing receivable, before allowance for credit loss		146,081
California
Mortgage Loans [Line Items]
Year one		0
Year two		0
Year three		1,268
Year four		1,248
Year five		0
Year six		0
Prior years, range 1		1,681
Prior years range 2		6,431
Prior years range 3		1,373
Financing receivable, before allowance for credit loss		12,001
7f7 and better
Mortgage Loans [Line Items]
Year one		471
Year two		0
Year three		2,019
Year four		1,541
Year five		440
Year six		0
Prior years, range 1		3,847
Prior years range 2		17,032
Prior years range 3		6,891
Financing receivable, before allowance for credit loss		32,241
6f6 and below
Mortgage Loans [Line Items]
Year one		0
Year two		1,351
Year three		1,783
Year four		1,470
Year five		209
Year six		368
Prior years, range 1		9,885
Prior years range 2		70,163
Prior years range 3		28,774
Financing receivable, before allowance for credit loss		114,003
18-1 LLC
Mortgage Loans [Line Items]
Year one		0
Year two		0
Year three		605
Year four		176
Year five		284
Year six		429
Prior years, range 1		819
Prior years range 2		33
Prior years range 3		10
Financing receivable, before allowance for credit loss		2,356
Non-PCD
Mortgage Loans [Line Items]
Year one		3,771
Year two		8,831
Year three		3,855
Year four		0
Year five		507
Year six		0
Prior years, range 1		0
Prior years range 2		0
Prior years range 3		0
Financing receivable, before allowance for credit loss		16,964
Ajax N | Mortgage Loans Held For Sale
Mortgage Loans [Line Items]
Year one		0
Year two		0
Year three		204
Year four		0
Year five		0
Year six		0
Prior years, range 1		4,267
Prior years range 2		15,893
Prior years range 3		9,208
Financing receivable, before allowance for credit loss		$ 29,572