EQUITY-BASED INCENTIVE AWARDS - Restricted Stock Unit Activity (Details) - Restricted Stock Units	3 Months Ended
	Dec. 31, 2017 $ / shares shares
Number of Shares
Nonvested restricted stock units at the beginning of the period (in shares) | shares	27,521
Granted (in shares) | shares	13,000
Vested (in shares) | shares	(13,710)
Nonvested restricted stock units at the end of the period (in shares) | shares	26,811
Weighted Average Fair Value
Nonvested restricted stock units at the beginning of the period (in dollars per share) | $ / shares	$ 92.25
Granted (in dollars per share) | $ / shares	90.50
Vested (in dollars per share) | $ / shares	90.97
Nonvested restricted stock units at the end of the period (in dollars per share) | $ / shares	$ 97.85