Schedule IV - Mortgage Loans on Real Estate (Changes in Mortgage Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract]
Balance, beginning of period	$ 18,790	$ 17,224	$ 13,161
Advances under real estate loans	0	1,566	7,458
Deductions	(9,476)	0	(3,395)
Balance, end of period	$ 9,314	$ 18,790	$ 17,224