Acquisitions - Additional Information (Detail) - Highlands Bancorp, Inc. $ / shares in Units, $ in Thousands		3 Months Ended		12 Months Ended
	Jan. 04, 2019 USD ($) branch $ / shares shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition, Contingent Consideration [Line Items]
Number of bank branches operated | branch	4
Conversion ratio (in shares) | shares	1.015
Consideration paid through common stock (in shares) | shares	2,837,524
Stock option payout price per share (in dollars per share) | $ / shares	$ 14.71
Average strike price (usd per share) | $ / shares	$ 8.09
Cash paid in connection with cancellation of the old stock options	$ 797
Goodwill adjustments			$ 1,700
Merger and acquisition integration-related expenses		$ 447		$ 3,200	$ 464