Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Furniture and fixtures	$ 1,793		$ 1,784
Leasehold improvements	19,862		19,676
Construction in progress	8,209
Property Plant And Equipment Gross	55,268		45,566
Less: accumulated depreciation	(35,469)		(30,923)
Property Plant And Equipment Net	19,799		14,643
Laboratory Equipment
Property, Plant and Equipment [Line Items]
Property, and equipment, useful life	5 years
Property and equipment other, gross	21,201		19,994
Computer Equipment And Software
Property, Plant and Equipment [Line Items]
Property, and equipment, useful life	3 years
Property and equipment other, gross	$ 4,203		$ 4,112
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property, and equipment, useful life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, and equipment, useful life	-	[1]
Construction in progress
Property, Plant and Equipment [Line Items]
Property, and equipment, useful life	0 years

[1] Shorter of asset life or lease term