Segment Reporting - Summary of Balance Sheet Information by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Goodwill	$ 2,868,068		$ 2,868,068	$ 2,631,465
Total assets	80,279,750		79,025,073
Net interest income	612,192	$ 567,739
Non-interest income	92,606	99,353
Total segment revenues	704,798	667,092
Compensation and benefits	198,645	188,540
Occupancy	19,717	19,439
Technology and equipment	47,719	45,836
Marketing	4,027	4,281
Segment pre-tax, pre-provision net revenue	361,154	331,169
Provision for credit losses	77,500	45,500
Total consolidated income before income taxes	283,654	285,669
Intangible assets amortization	9,237	9,194
Operating Segments
Segment Reporting Information [Line Items]
Net interest income	617,548	633,857
Non-interest income	84,552	99,319
Total segment revenues	702,100	733,176
Segment pre-tax, pre-provision net revenue	417,142	454,703
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Goodwill	1,960,363		1,960,363
Total assets	43,207,484		43,010,580
Net interest income	319,123	341,942
Non-interest income	28,958	34,280
Total segment revenues	348,081	376,222
Compensation and benefits	52,109	50,758
Occupancy	0	0
Technology and equipment	2,111	1,958
Marketing	0	0
Other segment items	52,362	53,509
Segment pre-tax, pre-provision net revenue	241,499	269,997
Intangible assets amortization	2,800	3,000
Operating Segments | Healthcare Financial Services
Segment Reporting Information [Line Items]
Goodwill	285,670		285,670
Total assets	481,222		488,194
Net interest income	96,361	86,138
Non-interest income	29,390	31,061
Total segment revenues	125,751	117,199
Compensation and benefits	23,337	21,362
Occupancy	0	0
Technology and equipment	8,764	8,006
Marketing	0	0
Other segment items	23,619	22,759
Segment pre-tax, pre-provision net revenue	70,031	65,072
Occupancy and technology depreciation	1,500	1,300
Intangible assets amortization	3,500	2,600
Operating Segments | Consumer Banking
Segment Reporting Information [Line Items]
Goodwill	622,035		622,035
Total assets	13,296,178		12,932,260
Net interest income	202,064	205,777
Non-interest income	26,204	33,978
Total segment revenues	228,268	239,755
Compensation and benefits	37,284	36,895
Occupancy	14,348	14,538
Technology and equipment	3,049	2,428
Marketing	1,982	1,847
Other segment items	65,993	64,413
Segment pre-tax, pre-provision net revenue	105,612	119,634
Occupancy and technology depreciation	2,500	2,300
Intangible assets amortization	1,800	2,200
Segment Reporting, Reconciling Item, Corporate Nonsegment
Segment Reporting Information [Line Items]
Goodwill	0		0
Total assets	23,294,866		$ 22,594,039
Non-interest income	8,054	34
Total segment revenues	2,698	(66,084)
Segment pre-tax, pre-provision net revenue	$ (55,988)	$ (123,534)