STOCK-BASED COMPENSATION - Restricted Stock and Restricted Stock Unit Activity (Details) - Restricted Stock Awards - $ / shares	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Shares/ Units
Vested (in shares)	(128,135)	(88,533)	(91,221)
Performance Vesting
Shares/ Units
Nonvested at beginning of period (in shares)	293,019
Granted (in shares)	216,476
Vested (in shares)	(60,388)
Forfeited (in shares)	(51,837)
Nonvested at end of period (in shares)	397,270	293,019
Weighted Average Grant Date Fair Value Per Share
Nonvested at beginning of period (in dollars per share)	$ 36.18
Granted (in dollars per share)	36.69
Vested (in dollars per share)	40.01
Forfeited (in dollars per share)	33.06
Nonvested at end of period (in dollars per share)	$ 36.28	$ 36.18
Time Vesting
Shares/ Units
Nonvested at beginning of period (in shares)	141,093
Granted (in shares)	61,247
Vested (in shares)	(67,747)
Forfeited (in shares)	(5,289)
Nonvested at end of period (in shares)	129,304	141,093
Weighted Average Grant Date Fair Value Per Share
Nonvested at beginning of period (in dollars per share)	$ 42.02
Granted (in dollars per share)	51.78
Vested (in dollars per share)	43.95
Forfeited (in dollars per share)	45.45
Nonvested at end of period (in dollars per share)	$ 44.89	$ 42.02