DESCRIPTION OF BUSINESS AND PRINCIPLES OF INTERIM STATEMENTS - Commercial Loan Investments and Accounts Receivable (Details)	3 Months Ended
	Dec. 31, 2015 Transaction	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Commercial Loan Investment Impairment
Allowance for impairment of loans		$ 0	$ 0
Accounts Receivable
Allowance for doubtful accounts		0	0
Trade Accounts Receivable Golf Operations
Accounts Receivable
Accounts receivable		353,000	349,000
Accounts Receivable Income Properties Tenant Reimbursable Expenses
Accounts Receivable
Accounts receivable		813,000	895,000
Accounts Receivable Real Estate Operations [Member]
Accounts Receivable
Accounts receivable		$ 2,100,000	$ 2,200,000
Number of closed land transactions | Transaction	2