Subsequent Event - Additional Information (Detail) - 130 Brookline Street [Member] $ in Millions		1 Months Ended	3 Months Ended
	Apr. 05, 2019 USD ($) ft²	Oct. 31, 2014	Mar. 31, 2019
Subsequent Event [Line Items]
Lease renewal term operating lease		5 years
Option to extend description operating lease			option to extend the term of the lease for an additional five-year period. In April 2019, the Company executed an amendment to the lease to extend the term of the lease for the additional five-year period. Refer to Note 11, Subsequent Event, for additional information regarding this lease amendment.
Operating lease, existence of option to extend		true
Lease expiration date			Jan. 31, 2020
Subsequent Event [Member]
Subsequent Event [Line Items]
Area of rentable square feet | ft²	15,169
Lease renewal term operating lease	5 years
Lessee operating lease extended expiration date	Jan. 31, 2025
Option to extend description operating lease	option to extend the term of the 130 Brookline Lease by five years from the original expiration date of January 31, 2020 to January 31, 2025, unless earlier terminated in accordance with the terms of the 130 Brookline Lease (the “Extension Term”)
Operating lease, existence of option to extend	true
Base rent	$ 0.1
Percentage of annual increase in lease	3.00%
Tenant improvement allowance	$ 0.2