EQUITY-BASED INCENTIVE AWARDS: (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
EQUITY-BASED INCENTIVE AWARDS:
Number of shares of the company's common stock permitted for issuance under the plan	150,000
Number of shares awarded pursuant to the plan	108,925
Number of shares that may be awarded under the plan	41,075
Stock options issued and outstanding
Weighted-Average Exercise Price (in dollars per share)	$ 54.53
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 54.53
Stock Options
Omnibus plan and stock option activity
Vesting period	5 years
Estimated fair value of the stock option awards using the Black-Scholes option pricing model	$ 0.1
Stock Option Pricing Assumptions
Risk-free interest rate (as a percent)	2.39%
Dividend yield (as a percent)	1.10%
Expected volatility (as a percent)	27.90%
Expected life	6 years
Expiration period	10 years
Stock options issued and outstanding
Number Outstanding (in shares)	37,042	30,583
Weighted-Average Exercise Price (in dollars per share)	$ 29.43	$ 24.05
Number Exercisable (in shares)	27,242
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 20.72
Number of Shares
Outstanding at the beginning of the period (in shares)	30,583
Granted (in shares)	6,500
Exercised (in shares)	(41)
Outstanding at the end of the period (in shares)	37,042	30,583
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)	$ 24.05
Granted (in dollars per share)	$ 54.74
Exercised (in dollars per share)	$ 28.80
Outstanding at the end of the period (in dollars per share)	$ 29.43	$ 24.05
Aggregate intrinsic value and fair value of options outstanding
Total unamortized compensation expense	0.1
Amortization period of unamortized compensation expense	40 months
Aggregate intrinsic value of options outstanding	1.3	1.0
Aggregate intrinsic value of options exercisable	1.2	1.0
Total intrinsic value of options exercised	0.1	0.1
Total fair value of options vested	$ 0.1	$ 0.1
Stock Options | Fiscal 2003
Stock options issued and outstanding
Number Outstanding (in shares)	42
Remaining Weighted-Average Contractual Life	25 days
Weighted-Average Exercise Price (in dollars per share)	$ 28.80
Number Exercisable (in shares)	42
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 28.80
Number of Shares
Outstanding at the end of the period (in shares)	42
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 28.80
Stock Options | Fiscal 2007
Stock options issued and outstanding
Number Outstanding (in shares)	25,000
Remaining Weighted-Average Contractual Life	4 years 2 months 12 days
Weighted-Average Exercise Price (in dollars per share)	$ 18.00
Number Exercisable (in shares)	25,000
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 18.00
Number of Shares
Outstanding at the end of the period (in shares)	25,000
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 18.00
Stock Options | Fiscal 2010
Stock options issued and outstanding
Number Outstanding (in shares)	5,500
Remaining Weighted-Average Contractual Life	7 years 6 months 29 days
Weighted-Average Exercise Price (in dollars per share)	$ 51.50
Number Exercisable (in shares)	2,200
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 51.50
Number of Shares
Outstanding at the end of the period (in shares)	5,500
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)	6,500
Remaining Weighted-Average Contractual Life	9 years 1 month 2 days
Weighted-Average Exercise Price (in dollars per share)	$ 54.74
Number of Shares
Outstanding at the end of the period (in shares)	6,500
Weighted Average Exercise Price
Outstanding at the end of the period (in dollars per share)	$ 54.74
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