Annual report pursuant to Section 13 and 15(d)

SHARE-BASED PAYMENTS - Narrative (Details)

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SHARE-BASED PAYMENTS - Narrative (Details) - USD ($)
$ in Thousands
12 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2015
Share-based compensation, aggregate disclosures [Abstract]      
Stock options outstanding 0    
Future income tax benefit from compensation expense recognized   $ 1,720 $ 418
Proceeds from the exercise of stock options $ 14 6,406 4,015
All Plans      
Share-based compensation, aggregate disclosures [Abstract]      
Total stock-based compensation cost 14,562 10,612 9,097
Future income tax benefit from compensation expense recognized 5,534 4,139 3,548
Proceeds from the exercise of stock options 14 6,406 4,015
Tax benefit realized from options exercised $ 3 $ 932 350
Options vested (in shares) 0 0  
All Plans | Stock Options      
Share-based compensation, aggregate disclosures [Abstract]      
Stock options outstanding 0 77,733  
Intrinsic value of options exercised $ 9 $ 2,692 $ 931
All Plans | Restricted Stock      
Share-based compensation, aggregate disclosures [Abstract]      
Unrecognized compensation cost on unvested awards $ 7,205    
Weighted average period of recognition of unrecognized compensation cost on non-vested awards 1 year 6 months    
All Plans | Restricted Stock | Prior to Fiscal Year 2013 | After 3 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 50.00%    
All Plans | Restricted Stock | Prior to Fiscal Year 2013 | After 4 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 16.67%    
All Plans | Restricted Stock | Prior to Fiscal Year 2013 | After 5 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 16.67%    
All Plans | Restricted Stock | Prior to Fiscal Year 2013 | After 6 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 16.66%    
All Plans | Restricted Stock | Fiscal 2013 and Thereafter | After 3 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 50.00%    
All Plans | Restricted Stock | Minimum      
Share-based compensation, aggregate disclosures [Abstract]      
Expiration period (in years) 3 years    
All Plans | Restricted Stock | Maximum      
Share-based compensation, aggregate disclosures [Abstract]      
Expiration period (in years) 5 years    
2012 Equity Incentive Plan      
Share-based compensation, aggregate disclosures [Abstract]      
Term of plan (in years) 10 years    
Maximum number of shares available for grants or awards (in shares) 2,500,000    
Shares reserved for future issuance under award plan (in shares) 589,238    
Retirement Eligible Employees      
Share-based compensation, aggregate disclosures [Abstract]      
Total stock-based compensation cost $ 3,337    
Pre-defined Levels of Adjusted Earnings Per Share | Restricted Stock | Fiscal 2013 and Thereafter | After 4 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 8.33%    
Pre-defined Levels of Adjusted Earnings Per Share | Restricted Stock | Fiscal 2013 and Thereafter | After 5 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 8.33%    
Pre-defined Levels of Adjusted Earnings Per Share | Restricted Stock | Fiscal 2013 and Thereafter | After 6 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 8.33%    
Pre-defined Levels of Appreciation in the Market Value of Common Stock | Restricted Stock | Fiscal 2013 and Thereafter | After 4 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 8.33%    
Pre-defined Levels of Appreciation in the Market Value of Common Stock | Restricted Stock | Fiscal 2013 and Thereafter | After 5 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 8.33%    
Pre-defined Levels of Appreciation in the Market Value of Common Stock | Restricted Stock | Fiscal 2013 and Thereafter | After 6 Years      
Share-based compensation, aggregate disclosures [Abstract]      
Vesting percentage 8.33%    
Director Fee Plans      
Director Fee Plan, aggregate disclosures [Abstract]      
Shares deferred under the director fee plan (in shares) 16,139    
Value of annual stock-based grant $ 125    
Option awards outstanding and vested (in shares) 0    
Total restricted stock awards granted to date (in shares) 161,724    
Restricted stock awards unvested (in shares) 25,157    
Director Fee Plans | Stock Options      
Director Fee Plan, aggregate disclosures [Abstract]      
Total stock options granted to date (in shares) 22,300    
2014 Director Fee Plan      
Share-based compensation, aggregate disclosures [Abstract]      
Shares reserved for future issuance under award plan (in shares) 150,000    
Director Fee Plan, aggregate disclosures [Abstract]      
Annual retainer fee paid to non-employee directors $ 75    
Annual retainer fee paid to non-employee chairman of the board $ 175    
Total restricted stock awards granted to date (in shares) 58,574