Schedule IV - Mortgage Loans on Real Estate - Reconciles Mortgage Loans on Real Estate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Balance at beginning of period	$ 49,929
Additions during period:
Loan fundings	191,437	$ 49,848
Amortization of deferred fees and expenses on loans	296	81
Deductions during period:
Collections of principal	(2,455)
Balance at end of period	$ 239,207	$ 49,929