Property and Equipment, net (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Property and equipment, net
Property and equipment, gross	$ 1,039	$ 590
Less accumulated depreciation and amortization	(435)	(350)
Property and equipment, net	604	240
Laboratory equipment
Property and equipment, net
Estimated useful life	4 years
Property and equipment, gross	358	328
Furniture and fixtures
Property and equipment, net
Estimated useful life	5 years
Property and equipment, gross	103	98
Office and computer equipment
Property and equipment, net
Estimated useful life	3 years
Property and equipment, gross	85	85
Leasehold improvements
Property and equipment, net
Property and equipment, gross	79	79
Construction in process
Property and equipment, net
Property and equipment, gross	$ 414