Real Estate Securities - Summary of Company's Real Estate Securities, CMBS (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 441,160	$ 386,316
CMBS 1
Debt Securities, Available-for-sale [Line Items]
Interest Rate	3.70%	4.70%
Par Value	$ 13,250	$ 13,250
Fair Value	$ 10,408	$ 13,274
CMBS 2
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.80%	3.80%
Par Value	$ 11,488	$ 12,131
Fair Value	$ 10,250	$ 12,151
CMBS 3
Debt Securities, Available-for-sale [Line Items]
Interest Rate	3.10%	4.10%
Par Value	$ 40,000	$ 40,000
Fair Value	$ 34,728	$ 40,186
CMBS 4
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.40%	3.70%
Par Value	$ 18,500	$ 18,500
Fair Value	$ 14,672	$ 18,535
CMBS 5
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.10%	3.10%
Par Value	$ 15,000	$ 15,000
Fair Value	$ 14,259	$ 15,019
CMBS 6
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.20%	3.20%
Par Value	$ 13,500	$ 13,500
Fair Value	$ 11,279	$ 13,525
CMBS 7
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.40%	3.40%
Par Value	$ 15,000	$ 15,000
Fair Value	$ 12,538	$ 15,028
CMBS 8
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.20%	3.20%
Par Value	$ 7,000	$ 7,000
Fair Value	$ 6,386	$ 7,013
CMBS 9
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.60%	3.60%
Par Value	$ 9,600	$ 9,600
Fair Value	$ 8,695	$ 9,641
CMBS 10
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.50%	3.50%
Par Value	$ 10,000	$ 10,000
Fair Value	$ 9,083	$ 10,027
CMBS 11
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.60%	3.60%
Par Value	$ 8,000	$ 8,000
Fair Value	$ 7,330	$ 8,015
CMBS 12
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.30%	3.30%
Par Value	$ 13,000	$ 13,000
Fair Value	$ 10,802	$ 13,022
CMBS 13
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.30%	3.30%
Par Value	$ 32,000	$ 32,000
Fair Value	$ 27,563	$ 32,074
CMBS 14
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.70%	3.70%
Par Value	$ 24,000	$ 24,000
Fair Value	$ 20,628	$ 24,084
CMBS 15
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.30%	3.30%
Par Value	$ 50,000	$ 50,000
Fair Value	$ 42,408	$ 50,094
CMBS 16
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.70%	3.70%
Par Value	$ 26,000	$ 26,000
Fair Value	$ 22,210	$ 26,029
CMBS 17
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.20%	3.20%
Par Value	$ 15,000	$ 15,000
Fair Value	$ 13,332	$ 15,022
CMBS 18
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.50%	3.50%
Par Value	$ 6,500	$ 6,500
Fair Value	$ 5,606	$ 6,509
CMBS 19
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.90%	3.90%
Par Value	$ 12,000	$ 12,000
Fair Value	$ 10,417	$ 12,022
CMBS 20
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.00%	3.10%
Par Value	$ 20,000	$ 20,000
Fair Value	$ 17,920	$ 20,021
CMBS 21
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.30%	3.40%
Par Value	$ 25,000	$ 25,000
Fair Value	$ 22,221	$ 25,025
CMBS 22
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.10%
Par Value	$ 22,500
Fair Value	$ 18,255
CMBS 23
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.50%
Par Value	$ 16,000
Fair Value	$ 13,166
CMBS 24
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.50%
Par Value	$ 2,000
Fair Value	$ 1,646
CMBS 25
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.10%
Par Value	$ 2,200
Fair Value	$ 1,785
CMBS 26
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.60%
Par Value	$ 12,500
Fair Value	$ 11,153
CMBS 27
Debt Securities, Available-for-sale [Line Items]
Interest Rate	3.00%
Par Value	$ 25,665
Fair Value	$ 23,056
CMBS 28
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.30%
Par Value	$ 28,000
Fair Value	$ 25,601
CMBS 29
Debt Securities, Available-for-sale [Line Items]
Interest Rate	2.60%
Par Value	$ 15,000
Fair Value	$ 13,763