Segment and Geographic Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011 years segment productcandidate product workforcereduction	Jun. 30, 2010	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segment			1
Net revenue	$ 119,591	$ 110,135	$ 231,728	$ 212,223
Long-lived assets	116,005		116,005		118,528
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	112,298	104,375	217,288	200,831
Percentage of revenue by geographic segments	93.90%	94.80%	93.80%	94.60%
Long-lived assets	114,675		114,675		117,095
Percentage of long-lived assets by geographic segments	98.90%		98.90%		98.80%
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	6,494	4,727	12,369	9,595
Percentage of revenue by geographic segments	5.40%	4.30%	5.30%	4.50%
Long-lived assets	1,230		1,230		1,213
Percentage of long-lived assets by geographic segments	1.10%		1.10%		1.00%
Rest of world [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	799	1,033	2,071	1,797
Percentage of revenue by geographic segments	0.70%	0.90%	0.90%	0.90%
Long-lived assets	$ 100		$ 100		$ 220
Percentage of long-lived assets by geographic segments	0.10%		0.10%		0.20%