Commitments and Contingencies - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($) ft²	Jun. 30, 2017 USD ($) LeaseTerm RenewalOption	Jun. 30, 2016 USD ($) ft²	Dec. 31, 2016 USD ($)	Mar. 31, 2016 ft²	Feb. 28, 2015 ft²
Operating Leased Assets [Line Items]
Total square footage of leased property | ft²							25,000
Additional operating lease term			2 years
Lease expiration date			Dec. 31, 2018
Security deposit	$ 500,000		$ 500,000		$ 500,000
Restricted cash	468,000		468,000		468,000
Rent expense	1,600,000	$ 1,000,000	2,900,000	$ 1,200,000
Letter of Credit | Bank Of America Merrill Lynch
Operating Leased Assets [Line Items]
Line of credit facility, maximum borrowing capacity					500,000
Collateral Pledged | Certificates of Deposit | Letter of Credit | Bank Of America Merrill Lynch
Operating Leased Assets [Line Items]
Restricted cash	$ 500,000		$ 500,000		$ 500,000
Office Laboratory Lease
Operating Leased Assets [Line Items]
Total square footage of leased property | ft²						56,000
Description of lease			The Company began incurring rent expense when the landlord delivered possession of the facility to the Company
Operating lease initial term			12 years
Operating lease extended term			13 years 6 months
Operating lease commencement date			2016-03
Operating lease, additional space | ft²		7,000
Additional lease option rights exercised | ft²		41,000		41,000
Number of additional renewal terms | LeaseTerm			2
Additional operating lease term			5 years
Office Laboratory Lease | Netherlands
Operating Leased Assets [Line Items]
Operating leases term of expiration			2017-12
Number of renewal options for operating leases | RenewalOption			1