Total Compensation Cost from Share-Based Payments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	$ 35,421	$ 20,341	$ 7,675
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	15,150	9,846	3,782
Selling, general and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	20,271	10,495	3,893
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	16,364	10,626	2,893
Stock and stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	18,458	9,467	4,601
Purchases of common stock at a discount
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation cost	$ 599	$ 248	$ 181