SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Goodwill impairment charge	$ 0	$ 0	$ 0
Goodwill
Goodwill, Balance at beginning of period	4,718	4,718
Additions	46,987
Goodwill, Balance at end of period	$ 51,705	$ 4,718	$ 4,718