Stockholder's Equity - Share-Based Employee Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share based compensation expense	$ 2,924	$ 3,082	$ 5,671	$ 6,097
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share based compensation expense	485	397	1,159	788
Selling, general and administrative expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share based compensation expense	$ 2,439	$ 2,685	$ 4,512	$ 5,309