Schedule IV (Consolidated) - Mortgage Loans on Real Estate - Carrying Amount of Mortgage Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in carrying amount of mortgage loans
Balance at beginning of the year	$ 1,462	$ 2,995	$ 242
Additions during the year - new mortgage loans	2,386	1,471	2,821
Collections of principal	1,165	3,004	68
Balance at the end of the year	$ 2,683	$ 1,462	$ 2,995