SEGMENT REPORTING - Operating Segments and Reconciliation of Information to Condensed Consolidated Financial Statements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Interest income	$ 495,667	$ 450,284	$ 423,560
Interest expense	68,663	25,766	60,401
Provision/ (credit) for credit losses	34,372	(45,556)	85,669
Non-interest income	87,019	102,055	102,716
Non-interest expenses	257,293	260,470	255,782
Income before income tax expense	222,358	311,659	124,424
Income tax expense	56,059	76,552	27,471
Net income	166,299	235,107	96,953
Assets	13,833,119	12,590,726	12,798,429
Inter-Segment Elimination
Segment Reporting Information [Line Items]
Interest income	(132)	(12)	(13)
Interest expense	(132)	(12)	(13)
Provision/ (credit) for credit losses	0	0	0
Non-interest income	(16,780)	(7,411)	(865)
Non-interest expenses	(719)	(868)	(865)
Income before income tax expense	(16,061)	(6,543)	0
Income tax expense	0	0	0
Net income	(16,061)	(6,543)	0
Assets	(92,341)	(67,659)	(71,211)
Community Banking | Operating Segments
Segment Reporting Information [Line Items]
Interest income	495,665	450,284	423,560
Interest expense	68,795	25,778	60,414
Provision/ (credit) for credit losses	34,372	(45,556)	85,669
Non-interest income	62,424	80,077	78,940
Non-interest expenses	238,953	240,996	237,910
Income before income tax expense	215,969	309,143	118,507
Income tax expense	49,670	74,036	25,907
Net income	166,299	235,107	92,600
Assets	13,853,476	12,590,176	12,800,537
Insurance | Operating Segments
Segment Reporting Information [Line Items]
Interest income	123	2	6
Interest expense	0	0	0
Provision/ (credit) for credit losses	0	0	0
Non-interest income	19,449	7,011	6,810
Non-interest expenses	3,755	5,869	5,686
Income before income tax expense	15,817	1,144	1,130
Income tax expense	4,472	339	313
Net income	11,345	805	817
Assets	17,777	9,110	11,335
Investment Management | Operating Segments
Segment Reporting Information [Line Items]
Interest income	11	10	7
Interest expense	0	0	0
Provision/ (credit) for credit losses	0	0	0
Non-interest income	21,926	22,378	17,831
Non-interest expenses	15,304	14,473	13,051
Income before income tax expense	6,633	7,915	4,787
Income tax expense	1,917	2,177	1,251
Net income	4,716	5,738	3,536
Assets	$ 54,207	$ 59,099	$ 57,768