Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation	$ 3,528	$ 2,674	$ 5,990	$ 5,525
Cost of Sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation	22	0	22	0
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation	419	511	852	955
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation	$ 3,087	$ 2,163	$ 5,116	$ 4,570