SHARE-BASED COMPENSATION PLANS (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Mar. 06, 2012	Mar. 02, 2012	Mar. 01, 2012
Omnibus Incentive Plan [Abstract]
Number of equity incentive awards		6
Number of shares authorized for issuance (in shares)					4,934,444
Number of shares authorized other than options or Sars (in shares)					2,030,952
Number of shares authorized for incentive stock options (in shares)					2,538,690
Number of shares authorized under newly issued plan					2,901,360
Number of shares available under previously existing plan (in shares)					2,033,084
Special cash dividend, leveraged recapitalization							$ 15.0000
Recapitalization ratio						1.45068
Closing price on dividend payment date							$ 51.9200
Opening price on ex-dividend date						$ 35.7900
Share based compensation expense		$ 13,306	$ 12,646	$ 11,643
Employee stock purchase plan [Abstract]
Number of shares issued, employee stock ownership plan (in shares)		70,645	61,364	38,050
Stock Options Activity [Roll Forward]
Exercised (in shares)		(976,645)	(1,085,965)	(74,019)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation - tax benefit		4,118	4,060	4,145
Total share-based compensation expense, net of tax		9,188	8,586	7,498
Number of non-employee directors who have completed two full terms of service					5
Fair value of awards for completing minimum full terms of service	749
Cost of Goods Sold [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense		1,541	1,221	986
Research, Development and technical [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense		1,105	1,060	908
Selling and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense		1,392	1,124	1,025
General and Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense		9,268	9,241	8,724
Director [Member]
Directors' deferred compensation plan [Abstract]
Cumulative number of shares deferred (in shares)		71,781	47,530
Deposit Share Plan [Member]
Omnibus Incentive Plan [Abstract]
Deposit share plan match in restricted shares (in hundredths)		50.00%
Employee Stock Purchase Plan [Member]
Omnibus Incentive Plan [Abstract]
Number of shares authorized for issuance (in shares)		814,625					975,000
Share based compensation expense		735	508	360
Employee stock purchase plan [Abstract]
Percentage annual earnings withheld to purchase stock, maximum (in hundredths)		10.00%
Maximum discounted stock purchase price (in hundredths)		85.00%
Number of shares issued, employee stock ownership plan (in shares)		70,645	61,364	38,050
Share based compensation arrangements, Fair value assumptions and methodology [Abstract]
Weighted-average grant date fair value - ESPP (in dollars per share)		$ 8.7800	$ 9.0500	$ 7.4500
Expected term (in years)		6 months	6 months	6 months
Expected volatility (in hundredths)		36.00%	28.00%	33.00%
Risk-free rate of return (in hundredths)		0.10%	0.20%	0.30%
Dividend yield (in hundredths)		0.00%	0.00%	0.00%
Directors' Deferred Compensation Plan [Member]
Omnibus Incentive Plan [Abstract]
Share based compensation expense		95	83	68
Stock Options [Member]
Omnibus Incentive Plan [Abstract]
Stock based compensation, contractual term (in years)		10 years
Stock based compensation, vesting period (in years)		4 years
Share based compensation expense		6,802	6,871	7,081
Share based compensation arrangements, Fair value assumptions and methodology [Abstract]
Weighted-average grant date fair value (in dollars per share)		$ 15.6600	$ 16.4900	$ 13.4200
Expected term (in years)		6 years 4 months 16 days	6 years 3 months 12 days	6 years 4 months 5 days
Expected volatility (in hundredths)		38.00%	36.00%	39.00%
Risk-free rate of return (in hundredths)		1.30%	2.10%	2.60%
Dividend yield (in hundredths)		0.00%	0.00%	0.00%
Stock Options Activity [Roll Forward]
Outstanding, beginning of period (in shares)		3,950,537
Granted (in shares)		477,444
Exercised (in shares)		(976,645)
Forfeited or canceled (in shares)		(98,104)
Mandatory proportional adjustment to stock options		1,780,394
Outstanding, end of period (in shares)		5,133,626	3,950,537
Exercisable, end of period ( in shares)		3,585,204
Expected to vest, end of period (in shares)		1,388,924
Weighted average exercise price, outstanding, beginning of period (in dollars per share)		$ 39.5200
Weighted average exercise price, granted (in dollars per share)		$ 39.5700
Weighted average exercise price, exercised (in dollars per share)		$ 34.9200
Weighted average exercise price, forfeited or canceled (in dollars per share)		$ 36.7600
Weighted average exercise price, outstanding, end of period (in dollars per share)		$ 26.7500	$ 39.5200
Weighted average exercise price, exercisable, end of period (in dollars per share)		$ 27.1800
Weighted average exercise price, expected to vest, end of period (in dollars per share)		$ 26.2100
Weighted average remaining contractual term, outstanding, end of period (in years)		4 years 11 months 25 days
Weighted average remaining contractual term, exercisable, end of period (in years)		3 years 4 months 26 days
Weighted average remaining contractual term, expected to vest, end of period (in years)		8 years 3 months 20 days
Aggregate intrinsic value, outstanding, end of period		44,262
Aggregate intrinsic value, exercisable, end of period		29,725
Aggregate intrinsic value, expected to vest, end of period		12,399
Closing stock price (in dollars per share)		$ 35.1400
Total intrinsic value of options exercised		6,879	13,135	492
Cash received from options exercised		34,107	35,955	2,283
Actual tax benefit realized for the tax deductions from options exercised		2,239	4,401	175
Total fair value of stock options vested		6,796	6,321	8,494
Total unrecognized share-based compensation expense		9,623
Compensation cost, weighted-average period for recognition (in years)		2 years 6 months
Restricted Stock [Member]
Omnibus Incentive Plan [Abstract]
Stock based compensation, vesting period (in years)		4 years
Share based compensation expense		5,674	5,184	4,134
Stock Options Activity [Roll Forward]
Total unrecognized share-based compensation expense		8,084
Compensation cost, weighted-average period for recognition (in years)		2 years 6 months
Restricted stock and restricted stock awards units [Roll Forward]
Restricted stocks awards and units, nonvested, beginning of period (in shares)		369,681
Restricted stocks awards and units, granted (in shares)		164,170
Restricted stocks awards and units, vested (in shares)		(167,159)
Restricted stocks awards and units, forfeited (in shares)		(10,242)
Mandatory proportional adjustment to restricted stock units		37,674
Restricted stocks awards and units, nonvested, end of period (in shares)		394,124	369,681
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)		$ 34.2900
Weighted average grant date fair value, granted (in dollars per share)		$ 39.7700
Weighted average grant date fair value, vested (in dollars per share)		$ 34.6000
Weighted average grant date fair value, forfeited (in dollars per share)		$ 31.5500
Weighted average grant date fair value, nonvested, end of period (in dollars per share)		$ 34.1500	$ 34.2900
Total fair values of restricted stock awards and restricted stock units vested		$ 5,784	$ 4,452	$ 3,209