COMMITMENTS AND CONTINGENCIES - Leases (Details) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2018 ft² $ / ft² period	Jul. 31, 2015 ft²	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Apr. 30, 2012 ft²
Leases
Aggregate rent payable			$ 10,989		$ 10,989
Enterprise FM Trust
Leases
Aggregate rent payable			1,000		$ 1,000
Enterprise FM Trust | Minimum
Leases
Lease terms					24 months
Enterprise FM Trust | Maximum
Leases
Lease terms					48 months
Office and laboratory
Leases
Rent expense			200	$ 100	$ 1,200	$ 400
Lease of cars
Leases
Rent expense			$ 100	$ 800	800	$ 2,400
New lease Newark
Leases
Square feet agreed to lease (sqft) | ft²								52,500
Additional square feet obligated lease (sqft) | ft²		8,000
Percent of subleased facility			60.00%
Aggregate rent payable			$ 6,800		6,800
Deferred rent			1,400		1,400		$ 1,400
Liability for deferred tenant improvement allowance			3,000		3,000
Lake Forest Illinois Building
Leases
Square feet agreed to lease (sqft) | ft²	31,000
Lease terms	5 years 6 months
Number of renewal periods (period) | period	1
Renewal terms	5 years
Written notice period	12 months
Initial annual base rent (in dollars per square foot) | $ / ft²	18.00
Annual increase in base rent (in dollars per square foot) | $ / ft²	0.50
Tenant improvement allowance (in dollars per square foot) | $ / ft²	28.00
Aggregate rent payable			$ 3,100		$ 3,100