Leases - Additional Information (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Weighted-average lease term	9 years	9 years
Operating lease ROU assets	$ 18,200	$ 18,200
Operating lease ROU liabilities	21,204	21,204
Operating lease, expense	$ 700	$ 1,300
Weighted average discount rate	3.29%	3.29%
Maximum [Member]
Operating lease terms	21 years	21 years
Operating lease term extensions	10 years	10 years
Minimum [Member]
Operating lease terms	1 year	1 year
Operating lease term extensions	5 years	5 years