DESCRIPTION OF BUSINESS AND PRINCIPLES OF INTERIM STATEMENTS - Accounts Receivable and Income Taxes (Details)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 Transaction
Accounts Receivable
Allowance for doubtful accounts	$ 0	$ 0
Income Taxes
Reserves for uncertain income tax positions	0
Receivables related to tenant reimbursable expenses
Accounts Receivable
Accounts receivable	553,000	125,000
Accounts receivable related to real estate operations
Accounts Receivable
Accounts receivable	2,400,000	3,800,000
Number of closed land transactions | Transaction			2
Trade accounts receivable related to golf operations
Accounts Receivable
Accounts receivable	$ 472,000	$ 326,000