Stock-Based Compensation Recognized on Condensed Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 3,268	$ 2,541	$ 1,850
Research and Development Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	482	554	450
Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,786	$ 1,987	$ 1,400