Summary of Significant Accounting Policies - Effects of Adoption of 2014-09 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Oct. 01, 2018	Sep. 30, 2018
Statement of Financial Position [Abstract]
Contract asset	$ 8,910		$ 8,910		$ 10,140	$ 0
Inventories, net	11,944		11,944		11,727	18,269
Contract liabilities (included within accrued liabilities)	1,000		1,000			0
Deferred income taxes	2,112		2,112			2,413
Retained earnings	30,743		30,743		40,695	37,097
Income Statement [Abstract]
Net sales	24,873	$ 28,681	81,331	$ 80,726
Cost of goods sold	23,486	25,402	75,119	72,889
Loss before income tax benefit	(7,706)	(1,750)	(10,727)	(4,937)
Net loss	$ (7,370)	$ (1,532)	$ (9,911)	$ (4,481)
Basic net loss per share (in dollars per share)	$ (1.32)	$ (0.28)	$ (1.78)	$ (0.81)
Diluted net loss per share (in dollars per share)	$ (1.32)	$ (0.28)	$ (1.78)	$ (0.81)
Income tax benefit	$ (336)	$ (218)	$ (816)	$ (456)
Accounting Standards Update 2014-09
Income Statement [Abstract]
Cost of goods sold			(210)
Previous Accounting Method
Statement of Financial Position [Abstract]
Contract asset	0		0			0
Inventories, net	17,170		17,170			18,269
Contract liabilities (included within accrued liabilities)	1,000		1,000
Deferred income taxes	2,112		2,112
Retained earnings	27,059		27,059			$ 37,097
Income Statement [Abstract]
Net sales	24,723		82,561
Cost of goods sold	22,849		76,435
Loss before income tax benefit	(7,219)		(10,813)
Net loss	$ (6,883)		$ (9,997)
Basic net loss per share (in dollars per share)	$ (1.23)		$ (1.80)
Diluted net loss per share (in dollars per share)	$ (1.23)		$ (1.80)
Effect of Accounting Change | Accounting Standards Update 2014-09
Statement of Financial Position [Abstract]
Contract asset	$ 8,910		$ 8,910		10,140
Inventories, net	(5,226)		(5,226)		(6,542)
Contract liabilities (included within accrued liabilities)	0		0
Deferred income taxes	0		0
Retained earnings	3,684		3,684		$ 3,598
Income Statement [Abstract]
Net sales	150		(1,230)
Cost of goods sold	637		(1,316)
Loss before income tax benefit	(487)		86
Net loss	$ (487)		$ 86
Basic net loss per share (in dollars per share)	$ (0.09)		$ 0.02
Diluted net loss per share (in dollars per share)	$ (0.09)		$ 0.02