Stock-based Compensation - Restricted Stock and Restricted Stock Unit Activity (Details) - Restricted Stock Awards	12 Months Ended
	Sep. 30, 2021 $ / shares shares
Performance Vesting
Shares/ Units
Nonvested at beginning of period (in shares) | shares	259,944
Granted (in shares) | shares	133,726
Vested (in shares) | shares	(55,619)
Forfeited (in shares) | shares	(25,455)
Nonvested at end of period (in shares) | shares	312,596
Weighted Average Grant Date Fair Value Per Share
Nonvested at beginning of period (in dollars per share) | $ / shares	$ 78.92
Granted (in dollars per share) | $ / shares	68.69
Vested (in dollars per share) | $ / shares	80.06
Forfeited (in dollars per share) | $ / shares	72.98
Nonvested at end of period (in dollars per share) | $ / shares	$ 74.33
Time Vesting
Shares/ Units
Nonvested at beginning of period (in shares) | shares	93,673
Granted (in shares) | shares	48,340
Vested (in shares) | shares	(30,313)
Forfeited (in shares) | shares	(1,400)
Nonvested at end of period (in shares) | shares	110,300
Weighted Average Grant Date Fair Value Per Share
Nonvested at beginning of period (in dollars per share) | $ / shares	$ 76.45
Granted (in dollars per share) | $ / shares	64.29
Vested (in dollars per share) | $ / shares	77.15
Forfeited (in dollars per share) | $ / shares	72.70
Nonvested at end of period (in dollars per share) | $ / shares	$ 70.98