Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Taxes [Line Items]
United States statutory tax rate	35.00%	35.00%	35.00%
Cash and cash equivalents held by foreign subsidiaries	$ 7,600
Temporary difference related to undistributed earnings	12,800	$ 13,000	$ 14,400
Valuation allowance against net deferred tax assets	20,087	7,715
United States
Income Taxes [Line Items]
Net operating loss, carryforwards	$ 24,100
Net operating loss, carryforwards expiration year	2037
Valuation allowance against net deferred tax assets	$ 23,600	4,000
Canada
Income Taxes [Line Items]
Net operating loss, carryforwards	$ 18,600
Net operating loss, carryforwards expiration year	2033
Valuation allowance against net deferred tax assets	$ 4,700	$ 3,700
Russia
Income Taxes [Line Items]
Net operating loss, carryforwards	$ 900
Net operating loss, carryforwards expiration year	2026
United Kingdom
Income Taxes [Line Items]
Net operating loss, carryforwards	$ 100