Business Segments - Financial Information by Business Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Interest and dividend income	$ 183,589	$ 134,117	$ 520,198	$ 364,738
Interest expense	65,907	9,616	156,618	20,299
NET INTEREST INCOME	117,682	124,501	363,580	344,439
Provision for credit losses	6,327	(535)	12,932	(4,785)
Net interest income after provision for credit losses	111,355	125,036	350,648	349,224
Non-interest income	30,879	32,256	90,372	89,622
Non-interest expense	97,939	91,941	290,498	266,511
Income before provision for income taxes	44,295	65,351	150,522	172,335
Provision for income taxes	7,453	12,318	26,458	32,432
Net income	36,842	53,033	124,064	139,903
Preferred stock dividends	2,531	2,531	7,594	7,594
Net income available to common shareholders	34,311	50,502	116,470	132,309
Community Banking [Member]
Segment Reporting Information [Line Items]
Interest and dividend income	183,589	134,117	520,198	364,738
Interest expense	65,907	9,616	156,618	20,299
NET INTEREST INCOME	117,682	124,501	363,580	344,439
Provision for credit losses	6,327	(535)	12,932	(4,785)
Net interest income after provision for credit losses	111,355	125,036	350,648	349,224
Non-interest income	24,175	25,739	69,256	68,743
Non-interest expense	92,815	88,144	276,247	254,484
Income before provision for income taxes	42,715	62,631	143,657	163,483
Provision for income taxes	7,121	11,747	25,016	30,573
Net income	35,594	50,884	118,641	132,910
Preferred stock dividends	2,531	2,531	7,594	7,594
Net income available to common shareholders	33,063	48,353	111,047	125,316
Trust and Investment Services [Member]
Segment Reporting Information [Line Items]
Non-interest income	6,704	6,517	21,116	20,879
Non-interest expense	5,124	3,797	14,251	12,027
Income before provision for income taxes	1,580	2,720	6,865	8,852
Provision for income taxes	332	571	1,442	1,859
Net income	1,248	2,149	5,423	6,993
Net income available to common shareholders	$ 1,248	$ 2,149	$ 5,423	$ 6,993