Mortgage Notes Receivable - Composition of loan portfolio (Details) - USD ($) $ in Thousands		Mar. 31, 2022		Dec. 31, 2021		Mar. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 940,078		$ 911,744
CECL Allowance		(8,647)	[1]	(10,394)	[2]	$ (10,663)	$ (10,590)
Carrying value, net		$ 931,431		$ 901,350
Percentage of portfolio		100.00%		100.00%
2022		$ 194,972	[3]	$ 597,269	[4]
2021		517,978	[3]	239,739	[4]
2020		164,528	[3]	3,102	[4]
2019		3,265	[3]	6,099	[4]
2018		5,000	[3]	65,274	[4]
Prior		$ 54,335	[3]	$ 261	[4]
LTV general percent indicating default status		65		65
Allowances on excess amortized cost over fair value				$ 700
0 - 40%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 53,404	[5]	$ 53,907
Percentage of portfolio		5.70%	[5]	5.90%
2022		$ 5,003	[5],[6]	$ 32,634	[7]
2021	[5],[6]	26,818
2019	[7]			3,608
2018		3,753	[5],[6]	17,665	[7]
Prior		17,830	[5],[6]	0	[7]
41 - 45%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 45,239	[5]	$ 48,431	[8]
Percentage of portfolio		4.80%	[5]	5.30%	[8]
2022		$ 11,667	[5],[6]	$ 44,380	[7],[8]
2021		29,554	[5],[6]	4,051	[7],[8]
2020	[5],[6]	4,018
46 - 50%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 62,403	[5]	$ 63,690	[8]
Percentage of portfolio		6.60%	[5]	7.00%	[8]
2022		$ 7,714	[5],[6]	$ 41,356	[7],[8]
2021		32,592	[5],[6]	21,317	[7],[8]
2020	[5],[6]	22,097
2019	[7],[8]			1,017
Prior	[7],[8]			0
51 - 55%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 122,558	[5]	$ 92,238	[8]
Percentage of portfolio		13.00%	[5]	10.10%	[8]
2022		$ 40,419	[5],[6]	$ 74,978	[7],[8]
2021		73,192	[5],[6]	17,260	[7],[8]
2020	[5],[6]	8,684
Prior	[5],[6]	263
56 - 60%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 63,159	[5]	$ 79,039	[8]
Percentage of portfolio		6.70%	[5]	8.70%	[8]
2022		$ 42,455	[5],[6]	$ 27,115	[7],[8]
2021		15,164	[5],[6]	40,190	[7],[8]
2020	[5],[6]	5,540
2018	[7],[8]			11,473
Prior	[7],[8]			261
61 - 65%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 572,393	[5]	$ 559,997	[8]
Percentage of portfolio		61.00%	[5]	61.40%	[8]
2022		$ 79,008	[5],[6]	$ 372,645	[7],[8]
2021		338,828	[5],[6]	146,640	[7],[8]
2020		113,803	[5],[6]	3,102	[7],[8]
2019		3,265	[5],[6]	1,474	[7],[8]
2018		1,247	[5],[6]	36,136	[7],[8]
Prior	[5],[6]	36,242
66 - 70%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 9,605	[5]	$ 645	[8]
Percentage of portfolio		1.00%	[5]	0.10%	[8]
2022		$ 8,706	[5],[6]	$ 645	[7],[8]
2021	[5],[6]	$ 899
71-80%
Loans and Leases Receivable Disclosure [Line Items]
Percentage of portfolio		0.00%		0.00%	[8]
Above 80%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 11,317	[5]	$ 13,797	[8]
CECL Allowance		$ (8,647)	[9]	$ (10,394)	[10]
Percentage of portfolio		1.20%	[5]	1.50%	[8]
2022	[7],[8]			$ 3,516
2021		$ 931	[5],[6]	10,281	[7],[8]
2020	[5],[6]	10,386
Apartments
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 115,043		$ 107,765
Percentage of portfolio		12.20%		11.80%
2022		$ 56,684	[11]	$ 38,232
2021		27,062	[11]	68,356	[12]
2020	[11]	29,963
2019		1,334	[11]	1,177	[12]
2018	[11]	0
Prior	[11]	0
Residential Lots
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 110,316		$ 111,644
Percentage of portfolio		11.80%		12.20%
2022		$ 12,428	[11]	$ 85,219
2021		71,309	[11]	26,425	[12]
2020	[11]	26,579
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Single family housing
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 103,128		$ 87,902
Percentage of portfolio		11.10%		9.60%
2022		$ 50,542	[11]	$ 84,703
2021		50,117	[11]	3,049	[12]
2020	[11]	2,319
2019	[11]	0
2018		0	[11]	150	[12]
Prior	[11]	150
Townhomes
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 84,810		$ 93,300
Percentage of portfolio		9.00%		10.20%
2022		$ 27,769	[11]	$ 51,240
2021		43,757	[11]	28,979	[12]
2020	[11]	12,691
2019		0	[11]	1,017	[12]
2018		0	[11]	11,803	[12]
Prior		593	[11]	261	[12]
Commercial
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 73,113		$ 61,592
Percentage of portfolio		7.80%		6.80%
2022		$ 5,950	[11]	$ 61,592
2021	[11]	67,163
2020	[11]	0
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Mixed Use
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 72,265		$ 85,929
Percentage of portfolio		7.70%		9.50%
2022		$ 1,104	[11]	$ 53,530
2021		58,454	[11]	30,474	[12]
2020		10,776	[11]	1,925	[12]
2019	[11]	1,931
2018	[11]	0
Prior		0	[11]	0	[12]
Condos
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 68,059		$ 64,492
Percentage of portfolio		7.20%		7.10%
2022		$ 4,201	[11]	$ 8,805
2021		6,330	[11]	18,227	[12]
2020	[11]	20,189
2019		0	[11]	1,474	[12]
2018		1,247	[11]	35,986	[12]
Prior		36,092	[11]	0	[12]
Senior Housing
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 64,119		$ 61,236
Percentage of portfolio		6.80%		6.70%
2022		$ 0	[11]	$ 35,899
2021		38,255	[11]	25,337	[12]
2020	[11]	25,864
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Storage
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 56,601		$ 56,481
Percentage of portfolio		6.00%		6.20%
2022		$ 0	[11]	$ 56,481
2021	[11]	56,601
2020	[11]	0
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Unentitled Land
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 48,113		$ 46,019
Percentage of portfolio		5.10%		5.00%
2022		$ 15,863	[11]	$ 42,411
2021	[11]	28,497
2020	[11]	0
2019	[11]	0
2018		3,753	[11]	3,608	[12]
Prior	[11]	0
Entitled Land
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 47,117		$ 45,098
Percentage of portfolio		5.00%		4.90%
2022		$ 960	[11]	$ 27,763
2021	[11]	28,657
2020	[11]	0
2019	[11]	0
2018		0	[11]	17,335	[12]
Prior	[11]	17,500
Hotel
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 32,159		$ 31,665
Percentage of portfolio		3.40%		3.50%
2022		$ 1,241	[11]	$ 4,886
2021		3,675	[11]	26,779	[12]
2020	[11]	27,243
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Offices
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 17,163		$ 15,348
Percentage of portfolio		1.80%		1.70%
2022		$ 0	[11]	$ 8,280
2021		9,747	[11]	7,068	[12]
2020	[11]	7,416
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Quadplex
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 11,427		$ 9,769
Percentage of portfolio		1.20%		1.10%
2022		$ 6,407	[11]	$ 9,769
2021	[11]	5,020
2020	[11]	0
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Commercial Lots
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 10,353		$ 10,227
Percentage of portfolio		1.10%		1.10%
2022		$ 3,664	[11]	$ 6,670
2021	[11]	6,689
2020		0	[11]	3,557	[12]
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Commercial other
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 9,723		$ 9,080
Percentage of portfolio		1.00%		1.00%
2022		$ 0	[11]	$ 9,080
2021		9,723	[11]	0	[12]
2020	[11]	0
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Retail
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 8,410		$ 7,873
Percentage of portfolio		0.90%		0.90%
2022		$ 0	[11]	$ 6,385
2021	[11]	6,922
2020		1,488	[11]	1,488	[12]
2019		0	[11]	0	[12]
2018	[11]	0
Prior	[11]	0
Duplex
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 7,381		$ 6,324
Percentage of portfolio		0.80%		0.70%
2022		$ 7,381	[11]	$ 6,324
2021	[11]	0
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Triplex
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 778
Percentage of portfolio		0.10%
2022	[11]	$ 778
2021	[11]	0
2020	[11]	0
2019	[11]	0
2018	[11]	0
Prior	[11]	0
Vertical Construction
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 495,037		$ 478,475
Percentage of portfolio		52.70%		52.50%
2022		$ 121,566	[3]	$ 234,861	[4]
2021		207,032	[3]	191,896	[4]
2020		127,173	[3]	1,177	[4]
2019		1,334	[3]	2,491	[4]
2018		1,247	[3]	47,789	[4]
Prior		36,685	[3]	261	[4]
Horizontal Development
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 202,100		$ 196,543
Percentage of portfolio		21.50%		21.50%
2022		$ 48,370	[3]	$ 169,041	[4]
2021		129,316	[3]	27,502	[4]
2020		24,414	[3]	0	[4]
2019		0	[3]	0	[4]
2018		0	[3]	0	[4]
Prior	[4]			0
Acquisition
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 98,990		$ 96,937
Percentage of portfolio		10.50%		10.60%
2022		$ 3,318	[3]	$ 96,937	[4]
2021		95,672	[3]	0	[4]
2020		0	[3]	0	[4]
2019		0	[3]	0	[4]
2018		0	[3]	0	[4]
Prior		0	[3]	0	[4]
Investment
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 65,962		$ 65,703
Percentage of portfolio		7.00%		7.20%
2022		$ 8,088	[3]	$ 42,509	[4]
2021		34,306	[3]	2,101	[4]
2020		2,165	[3]	0	[4]
2019		0	[3]	3,608	[4]
2018		3,753	[3]	17,485	[4]
Prior		17,650	[3]	0	[4]
Rehabilitation
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 31,968		$ 27,023
Percentage of portfolio		3.40%		3.00%
2022		$ 12,281	[3]	$ 11,320	[4]
2021		8,911	[3]	15,703	[4]
2020		10,776	[3]	0	[4]
2019		0	[3]	0	[4]
2018		0	[3]	0	[4]
Prior		0	[3]	0	[4]
Land Entitlement
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 25,350		$ 24,529
Percentage of portfolio		2.70%		2.70%
2022		$ 1,349	[3]	$ 24,529	[4]
2021		24,001	[3]	0	[4]
2020		0	[3]	0	[4]
2019		0	[3]	0	[4]
2018		0	[3]	0	[4]
Prior		0	[3]	0	[4]
Bridge
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 20,671		$ 22,534
Percentage of portfolio		2.20%		2.50%
2022		$ 0	[3]	$ 18,072	[4]
2021		18,740	[3]	2,537	[4]
2020		0	[3]	1,925	[4]
2019		1,931	[3]	0	[4]
2018		0	[3]	0	[4]
Prior		0	[3]	0	[4]
Unfunded Loan Commitment [Member]
Loans and Leases Receivable Disclosure [Line Items]
CECL Allowance	[13]	(1,097)		$ (904)		$ (947)	$ 0
Unfunded Loan Commitment [Member] | Accounts payable and accrued liabilities
Loans and Leases Receivable Disclosure [Line Items]
CECL Allowance		(1,100)
Allowances on excess amortized cost over fair value		$ 900

[1] Includes $0.9 million in loan specific allowances for loans deemed collateral dependent based on the excess amortized cost over the fair value of the underlying collateral. In addition, $1.1 million of the CECL allowance is excluded from this table because it relates to unfunded commitments and has been recorded as a liability under accounts payable and accrued liabilities in our condensed consolidated balance sheet.

[2] Includes $0.7 million in loan specific allowances for loans deemed collateral dependent based on the excess amortized cost over the fair value of the underlying collateral.

[3] Represents the year of either origination or amendment where the loan incurred a full re-underwriting in connection with the amendment.

[4] Represents the year of either origination or amendment where the loan incurred a full re-underwriting in connection with the amendment.

[5] Represents LTV as of origination or latest amendment. LTVs above 65% generally represent loans in contractual default status where we have agreed to extend funds to the borrower above 65% in order to facilitate successful completion of the construction and return of capital.

[6] Represents the year of either origination or amendment where the loan incurred a full re-underwriting in connection with the amendment.

[7] Represents the year of either origination or amendment where the loan incurred a full re-underwriting in connection with the amendment.

[8] Represents LTV as of origination or latest amendment. LTVs above 65% generally represent loans in contractual default status where we have agreed to extend funds to the borrower above 65% in order to ensure successful completion of the construction and return of capital.

[9] Includes $0.9 million in loan specific allowances for loans deemed collateral dependent based on the excess amortized cost over the fair value of the underlying collateral. In addition, $1.1 million of the CECL allowance is excluded from this table because it relates to unfunded commitments and has been recorded as a liability under accounts payable and accrued liabilities in our condensed consolidated balance sheet.

[10] Includes $0.7 million in loan specific allowances for loans deemed collateral dependent based on the excess amortized cost over the fair value of the underlying collateral.

[11] Represents the year of either origination or amendment where the loan incurred a full re-underwriting in connection with the amendment.

[12] Represents the year of either origination or amendment where the loan incurred a full re-underwriting in connection with the amendment.

[13] CECL allowance related to unfunded commitments is presented as a liability under accounts payable and accrued liabilities in our condensed consolidated balance sheet.