Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) Loan	Dec. 31, 2018 USD ($) Loan
Accounting Policies [Abstract]
Threshold period of delinquency	90 days
Number of loans on non-accrual status | Loan	0	0
Percentage of senior mortgage loan transferred to third-party	100.00%
Maximum insured amount of each cash account | $	$ 250,000	$ 250,000