Schedule IV - Mortgage Loans on Real Estate (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) property	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Mortgage Loans On Real Estate [Line Items]
Face Amount of Mortgages	$ 12,750,000
Carrying Amount of Mortgages	8,661,000
Principal Amount of Loans Subject to Delinquent Principal or Interest	0
Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at beginning of year	10,930,000	$ 14,430,000	$ 17,482,000
New mortgage loans	500,000	7,307,000	3,547,000
Collections of principal	(2,319,000)	(10,807,000)	(6,599,000)
Cost of mortgages sold	(450,000)	0	0
Balance at the close of year	8,661,000	10,930,000	14,430,000
Mortgages held for federal income tax purposes	8,661,000	10,930,000	14,430,000
Payments to acquire mortgage notes receivable	$ 500,000	$ 7,307,000	$ 3,547,000
Paramus, NJ
Mortgage Loans On Real Estate [Line Items]
Interest Rate	9.00%
Maturity Date	Feb. 01, 2022
Prior Liens	$ 0
Face Amount of Mortgages	6,000,000
Carrying Amount of Mortgages	3,338,000
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
Marlow Heights, MD
Mortgage Loans On Real Estate [Line Items]
Interest Rate	7.00%
Maturity Date	May 14, 2016
Prior Liens	$ 0
Face Amount of Mortgages	750,000
Carrying Amount of Mortgages	750,000
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
4 properties in FL and GA
Mortgage Loans On Real Estate [Line Items]
Number of Properties | property	4
Interest Rate	6.25%
Maturity Date	Jun. 30, 2015
Prior Liens	$ 0
Face Amount of Mortgages	5,500,000
Carrying Amount of Mortgages	4,073,000
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
Corpus Christi, TX
Mortgage Loans On Real Estate [Line Items]
Interest Rate	4.50%
Maturity Date	Mar. 01, 2018
Prior Liens	$ 0
Face Amount of Mortgages	500,000
Carrying Amount of Mortgages	500,000
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0