Income Taxes - CarryForwards (Details) - USD ($) $ in Thousands		12 Months Ended
	Jul. 10, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Net operating loss (NOL) carryforwards
Deferred tax assets related to available federal and state NOL carryforwards		$ 27,900	$ 28,400
Deferred tax assets related to available foreign NOL carryforwards		13,009	$ 10,163
Blended effective tax rate (as a percentage)			24.50%
Tax benefit relating to adjustment in corporate tax rate			$ 10,700
Increase (decrease) in valuation allowance		2,600
Valuation allowance		41,909	39,337
Undistributed foreign earnings		2,800
Cash and cash equivalents held overseas on which taxes would be incurred upon repatriation		21,000	14,400
Reconciliation of unrecognized tax benefits
Beginning balance		0	0	$ 725
Additions based on positions related to the current year		0	0	0
Additions for tax positions of prior years		273	107	1,426
Reductions for tax positions of prior years		0	(107)	(229)
Settlements		0	0	(1,922)
Ending balance		273	$ 0	$ 0
Foreign
Net operating loss (NOL) carryforwards
NOL's subject to expiration		400
Reconciliation of unrecognized tax benefits
Unrecognized tax benefits related to foreign operations		300
Machinio
Net operating loss (NOL) carryforwards
Percentage acquired	100.00%
Consideration paid	$ 19,900
Acquisition, deferred tax liability	$ 700
Acquisition, net operating loss		1,400
Machinio | Deferred Tax Asset Related To Business Acquisition
Net operating loss (NOL) carryforwards
Increase (decrease) in valuation allowance		$ 700