Segment Reporting - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Segment	Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of operating business segment	1
Number of components within business segment	2
Property and equipment, net	$ 72,215	$ 78,576
UCB [Member]
Segment Reporting Information [Line Items]
Percentage revenue from clients	30.00%
Roche [Member]
Segment Reporting Information [Line Items]
Percentage revenue from clients	23.00%	27.00%
Affymax, Inc. [Member]
Segment Reporting Information [Line Items]
Percentage revenue from clients	11.00%	16.00%
United States [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	62,500	67,700
Percent of net book value of property and equipment	87.00%	86.00%
India [Member]
Segment Reporting Information [Line Items]
Property and equipment, net	$ 9,700	$ 10,900
Percent of net book value of property and equipment	13.00%	14.00%