Supplementary Balance Sheet Information - Allowance for Sales Returns (Details) - Allowance for sales returns - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	$ 115	$ 133	$ 114
Provisions	(14)	(18)	19
Write-offs and Adjustments	0	0	0
Balance at End of Period	$ 101	$ 115	$ 133