Changes in Initial Product Warranty Accrual and Expenses Under Initial and Extended Warranties (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Movement in Standard Product Warranty Accrual
Initial warranty accrual, beginning balance	$ 930	$ 1,096
Provision for estimated warranty cost	970	148
Warranty expenditures	(233)	(219)
Initial warranty accrual, ending balance	1,667	1,025
Less warranty accrual, long-term	640	0	519
Total warranty accrual, current portion	$ 1,027	$ 1,025	$ 930