Stock-Based Compensation - Stock Option Plans (Details) - Employee and Directors Stock Options - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Nov. 19, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Fair value assumptions
Fair Value (in dollars per share)	$ 9.66
Dividend Yield (as a percent)	2.38%
Risk-Free Interest Rate (as a percent)	1.65%
Expected Volatility (as a percent)	35.00%
Expected Life	5 years
Stock-based employee compensation expense		$ 261	$ 178	$ 518	$ 331
Remaining unrecognized compensation expense		$ 2,100		$ 2,100
Weighted average period for recognition				2 years
Activity under stock option plans, number of shares
Outstanding at beginning of the period (in shares)				482,391
Granted (in shares)				91,466
Exercised (in shares)				(12,400)
Outstanding at end of the period (in shares)		561,457		561,457
Vested or expected to vest (in shares)		519,065		519,065
Exercisable at end of period (in shares)		245,517		245,517
Weighted Average Exercise Prices
Outstanding at beginning of the period (in dollars per share)				$ 38.05
Granted (in dollars per share)				37.00
Exercised (in dollars per share)				34.00
Outstanding at end of period (in dollars per share)		$ 37.97		37.97
Vested or expected to vest (in dollars per share)		37.90		37.90
Exercisable at end of the period (in dollars per share)		$ 42.17		$ 42.17
Outstanding at end of the period, Weighted Average Remaining Contractual Life				7 years 6 months 26 days
Vested or expected to vest, Weighted Average Remaining Contractual Life				7 years 7 months 21 days
Exercisable at end of the period, Weighted Average Remaining Contractual Life				5 years 6 months 4 days