Share-based Compensation - Share Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1,838	$ 2,809
Total share-based compensation expense capitalized into inventory		37
Cost of product sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	51	20
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	379	1,763
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1,408	$ 1,026