Product Warranty Costs - Product Warranty Liability (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Dec. 31, 2013
Composition of balance:        
Short-term $ 975 $ 981    
Long-term 1,686 1,633    
Total warranty balance $ 2,661 $ 2,614 $ 3,100 $ 3,090