Schedule IV - Mortgage Loans on Real Estate (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Rollforward of Mortgage loans on real estate
Balance at beginning of period	$ 0	$ 0	$ 1,900
Deductions during period:
Principal repayments and reductions	0	0	(1,900)
Deductions during period, total	0	0	(1,900)
Balance at end of period	$ 0	$ 0	$ 0