Summary of Company's Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 37,233	$ 32,377
Less accumulated depreciation	(17,103)	(17,328)
Property and equipment, net	20,130	15,049
Lab equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	8,332	7,728
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,210	306
Software and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,955	1,126
Building
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,856	1,856
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	21,359	10,058
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 521	$ 11,303