Mortgage Notes Receivable - Composition of loan portfolio (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019	[1]	Nov. 14, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 911,744		$ 809,076
CECL Allowance		(10,394)		(10,590)	$ (4,096)		$ (4,594)	$ (1,704)
Carrying value, net		$ 901,350		$ 798,486
Percentage of portfolio		100.00%		100.00%
2021		$ 597,269		$ 581,765
2020		239,739		90,775
2019		3,102		14,395
2018		6,099		105,099
2017		65,274		15,953
Prior		$ 261		$ 1,089
LTV general percent indicating default status		65		65
Allowances on excess amortized cost over fair value		$ 1,500		$ 1,500
0 - 40%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 53,907		$ 22,601
Percentage of portfolio		5.90%		2.80%
2021		$ 32,634		$ 18,112
2019				3,862
2018		3,608		261
2017		17,665
Prior				366
41 - 45%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 48,431		$ 68,263
Percentage of portfolio		5.30%		8.40%
2021		$ 44,380		$ 44,683
2020		4,051		20,183
2019				3,397
46 - 50%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 63,690		$ 23,864
Percentage of portfolio		7.00%		2.90%
2021		$ 41,356		$ 15,917
2020		21,317		7,224
2018		1,017
Prior				723
51 - 55%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 92,238		$ 76,539
Percentage of portfolio		10.10%		9.50%
2021		$ 74,978		$ 57,583
2020		17,260		2,774
2019
2018				16,182
56 - 60%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 79,039		$ 135,170
Percentage of portfolio		8.70%		16.70%
2021		$ 27,115		$ 117,309
2020		40,190		3,106
2018				9,639
2017		11,473		5,116
Prior		261
61 - 65%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 559,997		$ 450,253
Percentage of portfolio		61.40%		55.70%
2021		$ 372,645		$ 301,964
2020		146,640		57,488
2019		3,102		7,136
2018		1,474		76,139
2017		36,136		7,526
66 - 70%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 645		$ 9,416
Percentage of portfolio		0.10%		1.20%
2021		$ 645		$ 9,416
71 - 75%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value				$ 1,983
Percentage of portfolio		0.00%		0.20%
2021				$ 1,983
76 - 80%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value				$ 14,544
Percentage of portfolio		0.00%		1.80%
2021				$ 14,544
Above 80%
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 13,797		$ 6,443
Percentage of portfolio		1.50%		0.80%
2021		$ 3,516		$ 254
2020		10,281
2018				2,878
2017				3,311
Apartments
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 107,765		$ 129,588
Percentage of portfolio		11.80%		16.00%
2021		$ 38,232		$ 79,931
2020		68,356		18,953
2019		1,177
2018				24,232
2017				6,472
Prior
Residential Lots
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 111,644		$ 124,548
Percentage of portfolio		12.20%		15.40%
2021		$ 85,219		$ 105,830
2020		26,425		10,291
2017				8,427
Prior
Condos
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 64,492		$ 92,245
Percentage of portfolio		7.10%		11.40%
2021		$ 8,805		$ 52,714
2020		18,227		3,106
2019				4,405
2018		1,474		32,020
2017		35,986
Single family housing
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 87,902		$ 90,131
Percentage of portfolio		9.50%		11.10%
2021		$ 84,703		$ 69,438
2020		3,049		8,839
2019				1,028
2018				10,103
2017		150
Prior				723
Unentitled Land
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 46,019		$ 71,796
Percentage of portfolio		5.00%		8.90%
2021		$ 42,411		$ 47,727
2020
2019				7,259
2018		3,608		16,444
Prior				366
Townhomes
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 93,300		$ 72,773
Percentage of portfolio		10.20%		9.00%
2021		$ 51,240		$ 47,391
2020		28,979		1,061
2019				1,703
2018		1,017		21,564
2017		11,803		1,054
Prior		261
Mixed Use
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 85,929		$ 66,092
Percentage of portfolio		9.40%		8.20%
2021		$ 53,530		$ 60,232
2020		30,474		5,860
2019		1,925
Hotel
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 31,665		$ 51,115
Percentage of portfolio		3.50%		6.30%
2021		$ 4,886		$ 42,874
2020		26,779		8,241
Senior Housing
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 61,236		$ 34,283
Percentage of portfolio		6.70%		4.20%
2021		$ 35,899		$ 34,283
2020		25,337
Offices
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 15,348		$ 29,540
Percentage of portfolio		1.70%		3.70%
2021		$ 8,280		$ 8,495
2020		7,068		21,045
2019
Entitled Land
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 45,098		$ 1,116
Percentage of portfolio		4.90%		0.10%
2021		$ 27,763		$ 1,116
2018
2017		17,335
Commercial Lots
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 10,227		$ 15,683
Percentage of portfolio		1.10%		1.90%
2021		$ 6,670		$ 15,683
2020		3,557
Retail
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 7,873		$ 11,397
Percentage of portfolio		0.90%		1.40%
2021		$ 6,385		$ 9,500
2020		1,488		1,897
2019
Storage
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 56,481		$ 11,309
Percentage of portfolio		6.20%		1.40%
2021		$ 56,481		$ 704
2020				10,605
Quadplex
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 9,769		$ 5,592
Percentage of portfolio		1.10%		0.70%
2021		$ 9,769		$ 5,592
2020
Commercial
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 61,592		$ 877
Percentage of portfolio		6.80%		0.10%
2021		$ 61,592
2020				$ 877
Duplex
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 6,324		$ 736
Percentage of portfolio		0.70%		0.10%
2021		$ 6,324
2018				$ 736
Commercial other
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 9,080		$ 254
Percentage of portfolio		1.00%		0.10%
2021		$ 9,080		$ 254
Vertical Construction
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 471,863		$ 514,136
Percentage of portfolio		51.80%		63.50%
2021		$ 236,961		$ 354,012
2020		184,143		57,090
2019		1,177		6,853
2018		1,382		88,655
2017		47,939		7,526
Prior		261
Horizontal Development
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 182,945		$ 153,345
Percentage of portfolio		20.10%		19.00%
2021		$ 155,443		$ 129,607
2020		27,502		15,028
2019				283
2018
2017				8,427
Prior
Investment
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value		$ 256,936		$ 141,595
Percentage of portfolio		28.10%		17.50%
2021		$ 204,865		$ 98,146
2020		28,094		18,657
2019		1,925		7,259
2018		4,717		16,444
2017		17,335
Prior				1,089
Unfunded Loan Commitment [Member]
Loans and Leases Receivable Disclosure [Line Items]
CECL Allowance	[2]	(904)		$ 0
Unfunded Loan Commitment [Member] | Accounts payable and accrued liabilities
Loans and Leases Receivable Disclosure [Line Items]
CECL Allowance		(900)	$ (900)
Allowances on excess amortized cost over fair value		$ 700	$ 700

[1] The beginning balance on November 15, 2019 (Successor) represents the allowance of the acquirer, BRELF II

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