Stock Compensation Expense, Net of Amounts Capitalized into Inventory (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Compensation expense	$ 748,000	$ 891,000	$ 2,776,000	$ 3,110,000
Research and Development Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocation of stock-based compensation expense	198,000	273,000	576,000	896,000
Selling, General and Administrative Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocation of stock-based compensation expense	550,000	618,000	2,145,000	2,214,000
Restructuring Charges
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocation of stock-based compensation expense			55,000
1995 Equity Incentive Plan (the Equity Plan)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Compensation expense	733,000	883,000	2,744,000	3,078,000
Allocation of stock-based compensation expense	25,000		28,000
Employee Stock Purchase Plans
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Compensation expense	$ 15,000	$ 8,000	$ 32,000	$ 32,000