Subsequent Events - Additional Information (Detail) - Research Facility in Madison - ft²		1 Months Ended
	Jan. 01, 2019	Jan. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Additional office space leases, in square feet			60,000
Subsequent Event
Subsequent Event [Line Items]
Additional office space leases, in square feet		13,000
Lease extended term		through September 2029
Initial term of amended lease commencement date	Jan. 01, 2019