Expense Recognized for Stock Appreciation Units (Detail) (Stock Appreciation Rights (SARs), USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	$ (78)	$ (21)
Cost of Goods Sold
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	(24)	(5)
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	(32)	(9)
Selling and Marketing Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	(13)	(4)
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated share based compensation expense	$ (9)	$ (3)