SCHEDULE IV - MORTGAGE LOANS ON REAL ESTATE - Schedule of Mortgage Loans on Real Estate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal	$ 590,590	$ 92,863
Carrying Value	570,780	91,879
Office
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Carrying Value	269,865	38,106
Lab
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Carrying Value	13,398	31,078
Retail
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Carrying Value	88,724	17,029
Multifamily
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Carrying Value	106,002	0
Industrial
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Carrying Value	92,791	$ 5,666
First Mortgage Bridge Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal	590,590
Carrying Value	$ 570,780
First Mortgage Bridge Loans | Office | Downers Grove, IL
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.25%
Prior Liens	$ 0
Principal	29,500
Carrying Value	$ 29,384
First Mortgage Bridge Loans | Office | Aurora, IL
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.35%
Prior Liens	$ 0
Principal	14,710
Carrying Value	$ 14,660
First Mortgage Bridge Loans | Office | Miami, FL
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.50%
Prior Liens	$ 0
Principal	10,900
Carrying Value	$ 10,893
First Mortgage Bridge Loans | Office | Colorado Springs, CO
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.50%
Prior Liens	$ 0
Principal	29,642
Carrying Value	$ 29,426
First Mortgage Bridge Loans | Office | Plano, TX
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.75%
Prior Liens	$ 0
Principal	24,935
Carrying Value	$ 24,714
First Mortgage Bridge Loans | Office | St. Louis, MO
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.25%
Prior Liens	$ 0
Principal	28,421
Carrying Value	$ 28,498
First Mortgage Bridge Loans | Office | Yardley, PA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.75%
Prior Liens	$ 0
Principal	14,265
Carrying Value	$ 12,437
First Mortgage Bridge Loans | Office | Dublin, OH
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.75%
Prior Liens	$ 0
Principal	21,735
Carrying Value	$ 20,708
First Mortgage Bridge Loans | Office | Westminster, CO
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.75%
Prior Liens	$ 0
Principal	13,506
Carrying Value	$ 11,400
First Mortgage Bridge Loans | Office | Dallas, TX
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.25%
Prior Liens	$ 0
Principal	43,450
Carrying Value	$ 36,498
First Mortgage Bridge Loans | Office | Carlsbad, CA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.25%
Prior Liens	$ 0
Principal	23,740
Carrying Value	$ 23,499
First Mortgage Bridge Loans | Office | Downers Grove, IL
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.25%
Prior Liens	$ 0
Principal	23,530
Carrying Value	$ 23,407
First Mortgage Bridge Loans | Lab | Durham, NC
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.35%
Prior Liens	$ 0
Principal	13,500
Carrying Value	$ 13,398
First Mortgage Bridge Loans | Retail | Los Angeles, CA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.25%
Prior Liens	$ 0
Principal	18,374
Carrying Value	$ 18,409
First Mortgage Bridge Loans | Retail | Sandy Springs, GA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.75%
Prior Liens	$ 0
Principal	14,821
Carrying Value	$ 14,663
First Mortgage Bridge Loans | Retail | Coppell, TX
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.50%
Prior Liens	$ 0
Principal	19,615
Carrying Value	$ 18,685
First Mortgage Bridge Loans | Retail | West Bloomfield, MI
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.85%
Prior Liens	$ 0
Principal	37,388
Carrying Value	$ 36,968
First Mortgage Bridge Loans | Multifamily | Olmstead Falls, OH
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.00%
Prior Liens	$ 0
Principal	45,820
Carrying Value	$ 45,576
First Mortgage Bridge Loans | Multifamily | Portland, OR
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.57%
Prior Liens	$ 0
Principal	19,688
Carrying Value	$ 19,524
First Mortgage Bridge Loans | Multifamily | Seattle, WA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.55%
Prior Liens	$ 0
Principal	12,229
Carrying Value	$ 12,112
First Mortgage Bridge Loans | Multifamily | Portland, OR
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.57%
Prior Liens	$ 0
Principal	13,400
Carrying Value	$ 11,291
First Mortgage Bridge Loans | Multifamily | Bellevue, WA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.85%
Prior Liens	$ 0
Principal	20,000
Carrying Value	$ 19,792
First Mortgage Bridge Loans | Multifamily | Ames, IA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.80%
Prior Liens	$ 0
Principal	17,680
Carrying Value	$ 17,499
First Mortgage Bridge Loans | Industrial | Londonderry, NH
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	4.00%
Prior Liens	$ 0
Principal	34,391
Carrying Value	$ 34,170
First Mortgage Bridge Loans | Industrial | Allentown, PA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.50%
Prior Liens	$ 0
Principal	10,350
Carrying Value	$ 8,525
First Mortgage Bridge Loans | Industrial | Summerville, SC
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate	3.50%
Prior Liens	$ 0
Principal	35,000
Carrying Value	$ 34,644