Income Taxes - Summary of Deferred Income Taxes Assets And Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Document Fiscal Year Focus	2017
Noncurrent deferred tax assets:
Amortization and fixed assets	$ 1,835	$ 4,109
Accounts receivable	396	815
Inventories	2,254	2,899
Pension obligations	2,903	4,623
Warranty obligations	973	2,519
Accrued benefits	787	1,060
Foreign exchange contracts	89	460
Restricted stock	73	145
Tax credits carryforwards	1,611	2,238
Net operating loss carryforwards	24,784	20,130
Other temporary differences not currently available for tax purposes	(411)	2,135
Total noncurrent deferred tax assets	35,294	41,133
Valuation allowance	(15,021)	(12,546)
Net noncurrent deferred tax assets	20,273	28,587
Noncurrent deferred tax liabilities:
Amortization and fixed assets	(100)	(764)
Net operating loss carryforwards	0	2,178
Other temporary differences not currently available for tax purposes	60	(1,430)
Total noncurrent tax liabilities	(40)	(16)
Total net deferred tax asset	$ 20,233	$ 28,571