Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Blended tax rate		24.50%
Income tax expense (benefit)	$ (207)
Tax act, incomplete accounting, change in tax rate, deferred tax asset, provisional income tax expense (benefit)	$ 267
Tax act, transition tax		$ 240
Operating Loss Carryforwards [Line Items]
Liability for uncertain tax positions, excluding any related interest and penalties		53	$ 69
Portion of liability related to uncertain tax position which, if recognized, would impact the effective tax rate		53
Accrued (reversal of accrued) interest		21
Interest and penalties from continuing operations		2
Undistributed earnings of foreign subsidiaries		11,363
Revenue commissioners, Ireland | Subsidiaries
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		5,458
Foreign tax authority
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		1,956
Domestic tax authority
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		11,727
State tax authority
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		165
State and local jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		27,125
General Business Tax Credit Carryforward | Domestic tax authority
Operating Loss Carryforwards [Line Items]
Tax credit carryforward		$ 999