The Incentive Stock Plans - Summary of Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted, Options Outstanding		0
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Grant, Beginning Balance	1,386,561
Options granted, Shares Available for Grant	(5,000)
Options cancelled/forfeited/expired, Shares Available for Grant	14,750
Restricted stock awards granted, Shares Available for Grant	(341,517)
Restricted stock awards forfeited, Shares Available for Grant	61,925
Additional shares of stock issued, Shares Available for Grant	(69,472)
Shares Available for Grant, Ending Balance	1,047,247	1,386,561
Options Outstanding, Beginning Balance	1,207,504
Options granted, Options Outstanding	5,000
Options cancelled/forfeited/expired, Options Outstanding	(14,750)
Options exercised, Options Outstanding	(586,531)
Options Outstanding, Ending Balance	611,223	1,207,504
Exercisable as of September 30, 2018, Options Outstanding	607,889
Aggregate Intrinsic Value	$ 5,544	$ 5,737
Exercisable as of September 30, 2018, Aggregate Intrinsic Value	$ 5,537
Weighted Average Exercise Price, Beginning Balance	$ 11.81
Options granted, Weighted Average Exercise Price	18.95
Options cancelled/forfeited/expired, Weighted Average Exercise Price	12.27
Options exercised, Weighted Average Exercise Price	11.48
Weighted Average Exercise Price, Ending Balance	12.18	$ 11.81
Exercisable as of September 30, 2018, Weighted Average Exercise Price	$ 12.14
Weighted Average Remaining Contractual Life	4 years 4 months 24 days	5 years 3 months 18 days
Exercisable as of September 30, 2018, Weighted Average Remaining Contractual Life	4 years 4 months 24 days