Stock-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		109 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation	$ 638	$ 1,039	$ 1,503	$ 2,126	$ 31,939
Cash stock-based compensation					2,644
Total stock-based compensation	638	1,039	1,503	2,126	34,583
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	128	170	259	335	3,376
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	225	466	539	1,088	9,645
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	87		271		1,087
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	198	364	434	664	3,837
Warrants Issued | Selling, General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation		39		39	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