Leases - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating lease description	The Company leases office space and equipment, and certain office space is subleased. Management determines if a contract is a lease at the inception of the arrangement and reviews all options to extend, terminate, or purchase its right-of-use assets at the inception of the lease and accounts for these options when they are reasonably certain of being exercised.
Operating lease liability not yet commenced	$ 1.5