Loans Held for Investment - Loan Risk Ratings (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan	Mar. 31, 2020 USD ($)
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	14	12
Carrying value | $	$ 278,225	$ 242,078	$ 271,487
Weighted average risk rating	3.5	2.9
Percentage of Value	100.00%	100.00%
Risk Rating, 1
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	0	0
Carrying value | $	$ 0	$ 0
Risk Rating, 2
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	1	1
Carrying value | $	$ 24,547	$ 24,462
Risk Rating, 3
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	7	11
Carrying value | $	$ 137,789	$ 217,616
Risk Rating, 4
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	6	0
Carrying value | $	$ 115,889	$ 0
Percentage of Value	42.00%
Risk Rating, 5
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans | loan	0	0
Carrying value | $	$ 0	$ 0