Condensed Financial Information - Parent Company Only - Schedule of Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets:
Cash and due from banks	$ 62,555	$ 50,571
Interest-earning deposits with other banks	157,303	74,557
Cash and cash equivalents	219,858	125,128	$ 109,420	$ 75,409
Investments in subsidiaries, at equity in net assets:
Other assets	3,291	680
Total assets	6,336,496	5,380,924
Liabilities:
Subordinated notes	183,515	94,818
Other liabilities	52,198	44,514
Total liabilities	5,644,024	4,705,802
Shareholders' equity:	692,472	675,122	624,133	603,374
Total liabilities and shareholders' equity	6,336,496	5,380,924
Parent Company [Member]
Assets:
Cash and due from banks	154,422	82,673
Interest-earning deposits with other banks	211	177
Cash and cash equivalents	154,633	82,850	$ 79,042	$ 73,756
Investments in securities	818	1,004
Investments in subsidiaries, at equity in net assets:
Bank	719,146	685,387
Non-banks	0	0
Other assets	16,579	18,355
Total assets	891,176	787,596
Liabilities:
Dividends payable	0	5,865
Subordinated notes	183,515	94,818
Other liabilities	15,189	11,791
Total liabilities	198,704	112,474
Shareholders' equity:	692,472	675,122
Total liabilities and shareholders' equity	$ 891,176	$ 787,596