Stock-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		106 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation	$ 865	$ 1,087	$ 31,301
Cash stock-based compensation			2,644
Total stock-based compensation	865	1,087	33,945
Stock options and ESPP shares issued | Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation	131	165	3,248
Stock options and ESPP shares issued | Selling, General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation	314	622	9,420
Restricted Stock Issued To Employees And Board Members | Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation	184		1,000
Restricted Stock Issued To Employees And Board Members | Selling, General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation	236	300	3,639
Warrants Issued | Selling, General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation			13,994
Modified Stock Option Awards | Selling, General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation			1,500
Purchase Of Interest | Selling, General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation			$ 1,144