Stock-Based Compensation (Details 2) (USD $)	1 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allocation of stock-based compensation expense
Stock-based compensation expense		$ 24,916,000	$ 19,009,000	$ 20,000,000
Information related to share-based compensation
Expense recorded in connection with stock option modification	900,000
Non-employee options and RSUs
Allocation of stock-based compensation expense
Stock-based compensation expense		307,000	1,186,000	501,000
RSAs
Allocation of stock-based compensation expense
Stock-based compensation expense		5,498,000	398,000	470,000
Information related to share-based compensation
Total unrecognized compensation cost related to unvested stock-based compensation		5,389,000
Weighted-average remaining service period of recognition of unrecognized compensation cost (in years)		4.5
Stock options
Allocation of stock-based compensation expense
Stock-based compensation expense		4,528,000	7,003,000	10,271,000
Information related to share-based compensation
Total unrecognized compensation cost related to unvested stock-based compensation		7,293,000
Weighted-average remaining service period of recognition of unrecognized compensation cost (in years)		2.8
RSUs
Allocation of stock-based compensation expense
Stock-based compensation expense		13,290,000	9,783,000	7,473,000
Information related to share-based compensation
Total unrecognized compensation cost related to unvested stock-based compensation		12,449,000
Weighted-average remaining service period of recognition of unrecognized compensation cost (in years)		2.0
RSAs performance-contingent | Senior management
Information related to share-based compensation
Maximum potential expenses associated with 2011 performance-contingent restricted stock grant		31,900,000
RSAs performance-contingent | Officer
Information related to share-based compensation
Maximum potential expenses associated with 2011 performance-contingent restricted stock grant		475,000
Employee stock purchase plan
Allocation of stock-based compensation expense
Stock-based compensation expense		1,293,000	639,000	1,285,000
Research and development
Allocation of stock-based compensation expense
Stock-based compensation expense		13,422,000	10,322,000	11,542,000
Research and development | RSAs performance-contingent | Senior management
Information related to share-based compensation
Maximum potential expenses associated with 2011 performance-contingent restricted stock grant		6,300,000
General and administrative
Allocation of stock-based compensation expense
Stock-based compensation expense		11,494,000	8,687,000	8,458,000
General and administrative | RSAs performance-contingent | Senior management
Information related to share-based compensation
Maximum potential expenses associated with 2011 performance-contingent restricted stock grant		$ 25,600,000