Changes in Initial Product Warranty Accrual and Expenses Under Initial and Extended Warranties (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Standard Product Warranty Accrual
Initial warranty accrual, beginning balance	$ 1,096	$ 1,699	$ 2,218
Provision for estimated warranty cost	1,214	475	1,705
Warranty expenditures	(861)	(1,078)	(2,224)
Initial warranty accrual, ending balance	1,449	1,096	1,699
Less warranty accrual, long term	519	0	0
Total warranty accrual, current portion	$ 930	$ 1,096	$ 1,699