SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - LOAN RECEIVABLE (Details) - USD ($)	6 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable in other current assets	$ 8,200,000	$ 7,800,000
Loans receivable in other noncurrent assets	$ 40,700,000	39,500,000
Threshold period in establishing allowance for doubtful accounts	60 days
Allowance for doubtful accounts	$ 0	$ 0
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan term	2 years
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan term	10 years