Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2016
Valuation allowance - deferred tax assets
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 5,952		$ 5,914		$ 862
Charged to costs and expenses		521		136		5,260
Charged to Other Accounts		0		0		0
Deductions		3,182		98		208
Balance at end of period		3,291		5,952		5,914
Valuation account - doubtful accounts
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		341		209		285
Charged to costs and expenses		729		127		10
Charged to Other Accounts		40	[1]	20	[2]	0
Deductions	[3]	37		15		86
Balance at end of period		1,073		341		209
Reserve for future returns and pricing adjustments
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		2,169		1,991		1,817
Charged to costs and expenses		10,715		10,447		9,946
Charged to Other Accounts		0		0		0
Deductions		10,324		10,269		9,772
Balance at end of period		$ 2,560		$ 2,169		$ 1,991

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

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

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