Transactions between the Company and Related Parties - Related Party Transactions (Parenthetical) (Detail) - Bridgeview Facility [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) ft²
Related Party Transaction [Line Items]
Lease of Bridgeview Facility | ft²	40,000
Monthly lease payments | $	$ 22
Maximum rental escalation	2.00%
Extended lease expiration date	Jun. 30, 2020
Provision for lease extension periods	six one year
Notice period prior to expiration of lease	180 days
Rental escalation clause	Annual rent is increased during the initial lease term by the lesser of the increase in the Consumer Price Increase or 2.0%.