Summary of Significant Accounting Policies -Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Jan. 01, 2019
Leases [Line Items]
Lease, practical expedient	false
Operating lease assets	$ 11,899
Operating lease liability	$ 21,179
As reported under Topic 842 [Member]
Leases [Line Items]
Operating lease assets		$ 13,737
Operating lease liability		$ 24,497