Income Taxes (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
	Oct. 01, 2018	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Income Taxes
Statutory federal tax rate (as a percent)	21.00%	21.00%	24.50%	21.00%	24.50%	24.50%
Effective tax rate (as a percent)		26.00%		128.10%
Income (loss) before income taxes		$ 2,039	$ (2,009)	$ 335	$ (6,869)
Decrease in tax expense attributable to expiration of stock option grants		$ 300		$ 300
Increase in tax expense					$ 17,954