SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mortgage loans on real estate
Balance at the beginning of the period	$ 223,907	$ 229,801	$ 217,529
New mortgage loans	14,525		13,250
Other additions	6,839	11,913	7,435
Land conveyance		(4)
Amortization of mortgage premium	(4)	(17,863)	(10)
Collections of principal	(2,136)		(8,278)
Foreclosures		60
Loan loss reserve	(192)		(125)
Balance at the end of the period	$ 242,939	$ 223,907	$ 229,801