EQUITY-BASED INCENTIVE AWARDS - Stock Options (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2016 USD ($) item $ / shares shares	Sep. 30, 2015 USD ($) $ / shares shares
Omnibus plan and stock option activity
Number of incentive plans | item	2
Number of shares of the company's common stock permitted for issuance under the plan | shares	225,000
Number of shares awarded pursuant to the plan | shares	173,555
Number of additional shares that may be awarded under the plan | shares	51,445
Stock Options
Omnibus plan and stock option activity
Vesting period	5 years	5 years
Estimated fair value of the stock option awards using the Black-Scholes option pricing model | $	$ 0.1	$ 0.1
Expiration period	10 years	10 years
Stock Option Pricing Assumptions
Risk-free interest rate (as a percent)	1.98%	1.93%
Dividend yield (as a percent)	0.90%	0.90%
Expected volatility (as a percent)	24.30%	22.70%
Expected life	6 years	6 years
Stock options issued and outstanding
Number Outstanding (in shares) | shares	22,800	21,100
Weighted-Average Exercise Price (in dollars per share) | $ / shares	$ 69.79	$ 64.16
Number Exercisable (in shares) | shares	9,200
Exercisable, Weighted-Average Exercise Price (in dollars per share) | $ / shares	$ 59.05
Number of Shares
Granted (in shares) | shares	5,500	6,000
Exercised (in shares) | shares	(3,800)
Weighted Average Exercise Price
Granted (in dollars per share) | $ / shares	$ 83.90
Exercised (in dollars per share) | $ / shares	$ 58.95
Aggregate intrinsic value and fair value of options outstanding
Compensation expense related to the amortization of all equity - based compensation awards | $	$ 0.1	$ 0.1
Total unamortized compensation expense | $	$ 0.2
Amortization period of unamortized compensation expense	40 months
Aggregate intrinsic value of options outstanding | $	$ 0.5	0.3
Aggregate intrinsic value of options exercisable | $	0.3	0.2
Total intrinsic value of options | $	0.1	1.6
Total fair value of options vested | $	$ 0.4	$ 0.4