Significant Accounting Policies - Summary of Impact of New Revenue Standard on Opening Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018
PROPERTY, PLAN AND EQUIPMENT
Machinery, equipment and furniture	$ 59,637	$ 59,302	$ 50,606
Accumulated depreciation and amortization	(64,108)	(63,457)	(55,846)
OTHER ASSETS
Deferred instrument costs, net			1,239
NON-CURRENT LIABILITIES
Deferred income taxes	(3,861)	(3,731)	(3,769)
SHAREHOLDERS' EQUITY
Retained earnings	$ (52,291)	(49,486)	$ (49,602)
New Revenue Standard Adjustment [Member] | Accounting Standards Update 2014-09 [Member]
PROPERTY, PLAN AND EQUIPMENT
Machinery, equipment and furniture		8,696
Accumulated depreciation and amortization		(7,611)
OTHER ASSETS
Deferred instrument costs, net		(1,239)
NON-CURRENT LIABILITIES
Deferred income taxes		(38)
SHAREHOLDERS' EQUITY
Retained earnings		$ 116