EQUITY-BASED INCENTIVE AWARDS: (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
EQUITY-BASED INCENTIVE AWARDS
Number of shares of the company's common stock permitted for issuance under the plan			225,000
Number of shares awarded pursuant to the plan			161,588
Number of shares that may be awarded under the plan			63,412
Stock Options
Omnibus incentive plan and stock option activity
Granted (in shares)	6,000	0
Vesting period	5 years
Share Based Compensation Arrangement by Share Based Payment Award Options Grants in Period Grant Date Fair Value	$ 0.1
Stock Option Pricing Assumptions
Risk-free interest rate (as a percent)	1.93%
Dividend yield (as a percent)	0.90%
Expected volatility (as a percent)	22.70%
Expected life	6 years
Stock options issued and outstanding
Number Outstanding (in shares)	41,600	41,600	21,100	41,600
Weighted-Average Exercise Price (in dollars per share)	$ 33.69	$ 33.69	$ 64.16	$ 33.69
Number Exercisable (in shares)			9,100
Exercisable, Weighted-Average Exercise Price (in dollars per share)			$ 56.03
Number of Shares
Outstanding at the beginning of the period (in shares)	41,600
Granted (in shares)	6,000	0
Exercised (in shares)	(26,500)
Outstanding at the end of the period (in shares)	21,100	41,600
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)	$ 33.69
Granted (in dollars per share)	81.03
Exercised (in dollars per share)	20.14
Outstanding at the end of the period (in dollars per share)	$ 64.16	$ 33.69
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			$ 0.1
Amortization period of unamortized compensation expense	41 months
Aggregate intrinsic value of options outstanding			0.3	$ 2.1
Aggregate intrinsic value of options exercisable			$ 0.2	$ 1.8
Total intrinsic value of options	$ 1.6	0.1
Total fair value of options vested	$ 0.4	$ 0.4
Expiration period	10 years
Stock Options | Chief Executive Officer and Chairman
Number of Shares
Exercised (in shares)	(25,000)
Weighted Average Exercise Price
Exercised (in dollars per share)	$ 18.00
Stock Options | Fiscal 2010
Stock options issued and outstanding
Number Outstanding (in shares)	3,500		3,500
Remaining Weighted-Average Contractual Life	4 years 6 months 29 days
Weighted-Average Exercise Price (in dollars per share)	$ 51.50		$ 51.50
Number Exercisable (in shares)			3,500
Exercisable, Weighted-Average Exercise Price (in dollars per share)			$ 51.50
Number of Shares
Outstanding at the end of the period (in shares)	3,500
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 51.50
Stock Options | Fiscal 2012
Stock options issued and outstanding
Number Outstanding (in shares)	4,900		4,900
Remaining Weighted-Average Contractual Life	6 years 1 month 2 days
Weighted-Average Exercise Price (in dollars per share)	$ 55.15		$ 55.15
Number Exercisable (in shares)			2,700
Exercisable, Weighted-Average Exercise Price (in dollars per share)			$ 55.04
Number of Shares
Outstanding at the end of the period (in shares)	4,900
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 55.15
Stock Options | Fiscal 2012 | Minimum
Stock options issued and outstanding
Exercisable, Weighted-Average Exercise Price (in dollars per share)			53.80
Stock Options | Fiscal 2012 | Maximum
Stock options issued and outstanding
Exercisable, Weighted-Average Exercise Price (in dollars per share)			$ 65.97
Stock Options | Fiscal 2013
Stock options issued and outstanding
Number Outstanding (in shares)	6,700		6,700
Remaining Weighted-Average Contractual Life	7 years 26 days
Weighted-Average Exercise Price (in dollars per share)	$ 62.33		$ 62.33
Number Exercisable (in shares)			2,900
Exercisable, Weighted-Average Exercise Price (in dollars per share)			$ 62.33
Number of Shares
Outstanding at the end of the period (in shares)	6,700
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 62.33
Stock Options | Fiscal 2015
Stock options issued and outstanding
Number Outstanding (in shares)	6,000		6,000
Remaining Weighted-Average Contractual Life	9 years 3 months 29 days
Weighted-Average Exercise Price (in dollars per share)	$ 81.03		$ 81.03
Number of Shares
Outstanding at the end of the period (in shares)	6,000
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 81.03