Supplementary Balance Sheet Information (Tables)

12 Months Ended

Sep. 30, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Accounts Receivable

The following is a summary of accounts receivable at September 30, 2021 and 2020 (in thousands):

	September 30,
	2021		2020
Accounts receivable	$	124,195	$	101,937
Less allowance for expected credit losses		(4,318)		(7,146)
Accounts receivable, net	$	119,877	$	94,791

Allowance for Doubtful Accounts Activity

The allowance for expected credit losses for the fiscal years ended September 30, 2021, 2020 and 2019 is as follows (in thousands):

	Balance at				Reversals of		Balance at
	Beginning of				Bad Debt		End of
Description	Period		Provisions		Expense		Period
2021 Allowance for expected credit losses	$	7,146	$	3,445	$	(6,273)	$	4,318
2020 Allowance for expected credit losses		3,548		4,600		(1,002)		7,146
2019 Allowance for expected credit losses		463		3,327		(242)		3,548

Summary of Inventories

The following is a summary of inventories at September 30, 2021 and 2020 (in thousands):

	September 30,
	2021		2020
Inventories
Raw materials and purchased parts	$	27,644	$	17,991
Work-in-process		4,787		3,315
Finished goods		27,967		15,819
Total inventories	$	60,398	$	37,125

The activity for excess and obsolete inventory reserves is as follows for the fiscal years ended September 30, 2021, 2020 and 2019 (in thousands):

	Balance at				Inventory		Balance at
	Beginning of				Disposals and		End of
Description	Period			Provisions	Adjustments		Period
2021 Reserves for excess and obsolete inventory	$	3,136	$	1,522	$	(977)	$	3,681
2020 Reserves for excess and obsolete inventory		3,157		1,515		(1,536)		3,136
2019 Reserves for excess and obsolete inventory		3,421		1,815		(2,079)		3,157

Valuation Allowance for Deferred Tax Assets Activity

The activity for valuation allowance for deferred tax assets is as follows for the fiscal years ended September 30, 2021, 2020 and 2019 (in thousands):

	Balance at						Balance at
	Beginning of		Charged to		Charged to		End of
Description	Period		Income Tax Benefit		Other Accounts		Period
2021 Valuation allowance for deferred tax assets	$	10,623	$	(3,247)	$	1,216	$	8,592
2020 Valuation allowance for deferred tax assets		12,843		(2,514)		294		10,623
2019 Valuation allowance for deferred tax assets		14,613		(1,834)		64		12,843

Product Warranty and Retrofit Activity on Gross Basis

	Amount
Balance at September 30, 2018	$	2,561
Accruals for warranties during the year		2,014
Costs incurred during the year		(2,261)
Balance at September 30, 2019		2,314
Accruals for warranties during the year		2,779
Costs incurred during the year		(2,882)
Balance at September 30, 2020		2,211
Accruals for warranties during the year		2,300
Costs incurred during the year		(2,181)
Balance at September 30, 2021	$	2,330