Segment Reporting - Summary of Balance Sheet Information by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Goodwill	$ 2,868,068		$ 2,868,068		$ 2,868,068	$ 2,631,465
Total assets	81,914,270		81,914,270		79,025,073
Net interest income	621,182	$ 572,297	1,233,374	$ 1,140,036
Non-interest income	94,657	42,298	187,263	141,651
Total segment revenues	715,839	614,595	1,420,637	1,281,687
Compensation and benefits	199,930	186,850	398,575	375,390
Occupancy	19,337	15,103	39,054	34,542
Technology and equipment	45,932	45,303	93,651	91,139
Marketing	5,171	4,107	9,198	8,388
Segment pre-tax, pre-provision net revenue	370,125	288,574	731,279	619,743
Provision for credit losses	46,500	59,000	124,000	104,500
Total consolidated income before income taxes	323,625	229,574	607,279	515,243
Intangible assets amortization	9,093	8,716	18,330	17,910
Operating Segments
Segment Reporting Information [Line Items]
Net interest income	628,815	631,931	1,246,363	1,265,788
Non-interest income	83,906	86,367	168,458	185,686
Total segment revenues	712,721	718,298	1,414,821	1,451,474
Segment pre-tax, pre-provision net revenue	425,852	446,538	842,994	901,241
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Goodwill	1,960,363		1,960,363		1,960,363
Total assets	43,908,431		43,908,431		43,010,580
Net interest income	318,518	337,588	637,641	679,530
Non-interest income	30,628	34,510	59,586	68,790
Total segment revenues	349,146	372,098	697,227	748,320
Compensation and benefits	50,807	49,904	102,916	100,662
Occupancy	0	0	0	0
Technology and equipment	2,336	2,051	4,447	4,009
Marketing	0	0	0	0
Other segment items	55,229	52,633	107,591	106,142
Segment pre-tax, pre-provision net revenue	240,774	267,510	482,273	537,507
Occupancy and technology depreciation	100	100	100	100
Intangible assets amortization	2,700	1,700	5,500	4,700
Operating Segments | Healthcare Financial Services
Segment Reporting Information [Line Items]
Goodwill	285,670		285,670		285,670
Total assets	477,234		477,234		488,194
Net interest income	97,625	91,664	193,986	177,802
Non-interest income	28,687	27,465	58,077	58,526
Total segment revenues	126,312	119,129	252,063	236,328
Compensation and benefits	24,171	22,915	47,508	44,277
Occupancy	0	0	0	0
Technology and equipment	7,524	8,092	16,288	16,098
Marketing	0	0	0	0
Other segment items	23,758	20,260	47,377	43,019
Segment pre-tax, pre-provision net revenue	70,859	67,862	140,890	132,934
Occupancy and technology depreciation	1,500	1,300	2,900	2,600
Intangible assets amortization	3,400	3,600	6,900	6,300
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Goodwill	622,035		622,035		622,035
Total assets	13,499,277		13,499,277		12,932,260
Net interest income	212,672	202,679	414,736	408,456
Non-interest income	24,591	24,392	50,795	58,370
Total segment revenues	237,263	227,071	465,531	466,826
Compensation and benefits	37,285	36,526	74,569	73,421
Occupancy	13,835	13,683	28,183	28,221
Technology and equipment	2,917	2,331	5,966	4,759
Marketing	2,043	1,714	4,025	3,561
Other segment items	66,964	61,651	132,957	126,064
Segment pre-tax, pre-provision net revenue	114,219	111,166	219,831	230,800
Occupancy and technology depreciation	2,400	2,300	5,000	4,600
Intangible assets amortization	1,800	2,100	3,600	4,300
Segment Reporting, Reconciling Item, Corporate Nonsegment
Segment Reporting Information [Line Items]
Goodwill	0		0		0
Total assets	24,029,328		24,029,328		$ 22,594,039
Non-interest income	10,751	(44,069)	18,805	(44,035)
Total segment revenues	3,118	(103,703)	5,816	(169,787)
Segment pre-tax, pre-provision net revenue	$ (55,727)	$ (157,964)	$ (111,715)	$ (281,498)