Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2015
Valuation Allowance - Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 5,914		$ 862	$ 572
Increase to costs and expenses		136		5,260	316
Valuation Allowances and Reserves, Additions for Charges to Other Accounts		0		0	0
Deductions		98		208	26
Balance at end of period		5,952		5,914	862
Valuation Account - Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		209		285	367
Increase to costs and expenses		127		10	4
Valuation Allowances and Reserves, Additions for Charges to Other Accounts		20	[1]	0	0
Deductions	[2]	15		86	86
Balance at end of period		341		209	285
Reserve for Future Returns and Pricing Adjustments
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		1,991		1,817	1,662
Increase to costs and expenses		10,447		9,946	7,002
Valuation Allowances and Reserves, Additions for Charges to Other Accounts		0		0	0
Deductions		10,269		9,772	6,847
Balance at end of period		$ 2,169		$ 1,991	$ 1,817

[1] Established through purchase accounting relating to the acquisition of SMART Temps

[2] Uncollectible accounts charged against allowance, net of recoveries