Loans and Leases - Credit Quality Indicators (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable
Loans and leases	$ 53,056,223		$ 52,505,168
Current period gross write-offs
Total	56,618	$ 39,791
Consumer portfolio
Financing Receivable
Total financing receivable, Current fiscal year	332,734		1,298,754
Total financing receivable, Fiscal year before current fiscal year	1,503,949		763,519
Total financing receivable, Two years before current fiscal year	740,780		1,924,258
Total financing receivable, Three years before current fiscal year	1,905,000		2,156,856
Total financing receivable, Four years before current fiscal year	2,130,056		811,965
Total financing receivable, More than five years before current fiscal year	3,150,300		2,420,593
Revolving Loans Amortized Cost Basis	1,029,434		1,061,222
Loans and leases	10,792,253		10,437,167
Current period gross write-offs
Current fiscal year	615		3,467
Fiscal year before current fiscal year	244		17
Two years before current fiscal year	8		34
Three years before current fiscal year	0		20
Four years before current fiscal year	0		115
More than five years before current fiscal year	46		784
Revolving Loans Amortized Cost Basis	139		573
Total	1,052	$ 1,330	5,010
Consumer portfolio | Residential
Financing Receivable
Total financing receivable, Current fiscal year	282,069		1,151,655
Total financing receivable, Fiscal year before current fiscal year	1,275,748		697,121
Total financing receivable, Two years before current fiscal year	677,811		1,862,151
Total financing receivable, Three years before current fiscal year	1,844,680		2,082,332
Total financing receivable, Four years before current fiscal year	2,057,497		770,546
Total financing receivable, More than five years before current fiscal year	2,985,195		2,289,864
Revolving Loans Amortized Cost Basis	0		0
Loans and leases	9,123,000		8,853,669
Current period gross write-offs
Current fiscal year	0		0
Fiscal year before current fiscal year	0		0
Two years before current fiscal year	0		0
Three years before current fiscal year	0		0
Four years before current fiscal year	0		0
More than five years before current fiscal year	15		147
Revolving Loans Amortized Cost Basis	0		0
Total	15		147
Consumer portfolio | Home equity
Financing Receivable
Total financing receivable, Current fiscal year	9,271		37,780
Total financing receivable, Fiscal year before current fiscal year	37,024		64,724
Total financing receivable, Two years before current fiscal year	61,483		61,048
Total financing receivable, Three years before current fiscal year	59,408		72,184
Total financing receivable, Four years before current fiscal year	70,358		40,991
Total financing receivable, More than five years before current fiscal year	164,239		129,910
Revolving Loans Amortized Cost Basis	990,346		1,021,055
Loans and leases	1,392,129		1,427,692
Current period gross write-offs
Current fiscal year	0		0
Fiscal year before current fiscal year	51		0
Two years before current fiscal year	0		0
Three years before current fiscal year	0		0
Four years before current fiscal year			2
More than five years before current fiscal year	6		444
Revolving Loans Amortized Cost Basis	101		351
Total	158		797
Consumer portfolio | Other consumer
Financing Receivable
Total financing receivable, Current fiscal year	41,394		109,319
Total financing receivable, Fiscal year before current fiscal year	191,177		1,674
Total financing receivable, Two years before current fiscal year	1,486		1,059
Total financing receivable, Three years before current fiscal year	912		2,340
Total financing receivable, Four years before current fiscal year	2,201		428
Total financing receivable, More than five years before current fiscal year	866		819
Revolving Loans Amortized Cost Basis	39,088		40,167
Loans and leases	277,124		155,806
Current period gross write-offs
Current fiscal year	615		3,467
Fiscal year before current fiscal year	193		17
Two years before current fiscal year	8		34
Three years before current fiscal year	0		20
Four years before current fiscal year	0		113
More than five years before current fiscal year	25		193
Revolving Loans Amortized Cost Basis	38		222
Total	879		4,066
800+ | Consumer portfolio | Residential
Financing Receivable
Total financing receivable, Current fiscal year	54,360		312,771
Total financing receivable, Fiscal year before current fiscal year	466,968		299,006
Total financing receivable, Two years before current fiscal year	289,341		909,109
Total financing receivable, Three years before current fiscal year	908,689		1,097,807
Total financing receivable, Four years before current fiscal year	1,065,848		433,950
Total financing receivable, More than five years before current fiscal year	1,308,236		956,478
Revolving Loans Amortized Cost Basis	0		0
Loans and leases	4,093,442		4,009,121
800+ | Consumer portfolio | Home equity
Financing Receivable
Total financing receivable, Current fiscal year	2,601		12,313
Total financing receivable, Fiscal year before current fiscal year	13,140		25,226
Total financing receivable, Two years before current fiscal year	25,403		23,512
Total financing receivable, Three years before current fiscal year	24,795		32,695
Total financing receivable, Four years before current fiscal year	30,267		22,705
Total financing receivable, More than five years before current fiscal year	73,551		53,844
Revolving Loans Amortized Cost Basis	347,289		365,741
Loans and leases	517,046		536,036
800+ | Consumer portfolio | Other consumer
Financing Receivable
Total financing receivable, Current fiscal year	1,294		4,920
Total financing receivable, Fiscal year before current fiscal year	8,541		312
Total financing receivable, Two years before current fiscal year	268		218
Total financing receivable, Three years before current fiscal year	182		1,765
Total financing receivable, Four years before current fiscal year	1,738		50
Total financing receivable, More than five years before current fiscal year	246		284
Revolving Loans Amortized Cost Basis	13,253		31,549
Loans and leases	25,522		39,098
740-799 | Consumer portfolio | Residential
Financing Receivable
Total financing receivable, Current fiscal year	197,127		649,118
Total financing receivable, Fiscal year before current fiscal year	616,387		258,699
Total financing receivable, Two years before current fiscal year	242,333		567,545
Total financing receivable, Three years before current fiscal year	571,212		656,599
Total financing receivable, Four years before current fiscal year	665,571		235,749
Total financing receivable, More than five years before current fiscal year	852,295		623,989
Revolving Loans Amortized Cost Basis	0		0
Loans and leases	3,144,925		2,991,699
740-799 | Consumer portfolio | Home equity
Financing Receivable
Total financing receivable, Current fiscal year	2,375		12,238
Total financing receivable, Fiscal year before current fiscal year	11,925		21,831
Total financing receivable, Two years before current fiscal year	19,149		20,718
Total financing receivable, Three years before current fiscal year	18,099		23,517
Total financing receivable, Four years before current fiscal year	24,747		10,861
Total financing receivable, More than five years before current fiscal year	41,401		33,703
Revolving Loans Amortized Cost Basis	312,316		330,691
Loans and leases	430,012		453,559
740-799 | Consumer portfolio | Other consumer
Financing Receivable
Total financing receivable, Current fiscal year	16,146		45,001
Total financing receivable, Fiscal year before current fiscal year	76,296		721
Total financing receivable, Two years before current fiscal year	522		301
Total financing receivable, Three years before current fiscal year	213		165
Total financing receivable, Four years before current fiscal year	145		124
Total financing receivable, More than five years before current fiscal year	272		266
Revolving Loans Amortized Cost Basis	7,459		3,550
Loans and leases	101,053		50,128
670-739 | Consumer portfolio | Residential
Financing Receivable
Total financing receivable, Current fiscal year	29,925		172,886
Total financing receivable, Fiscal year before current fiscal year	170,615		123,354
Total financing receivable, Two years before current fiscal year	121,947		317,373
Total financing receivable, Three years before current fiscal year	287,984		271,247
Total financing receivable, Four years before current fiscal year	260,903		80,318
Total financing receivable, More than five years before current fiscal year	650,268		550,252
Revolving Loans Amortized Cost Basis	0		0
Loans and leases	1,521,642		1,515,430
670-739 | Consumer portfolio | Home equity
Financing Receivable
Total financing receivable, Current fiscal year	4,034		11,416
Total financing receivable, Fiscal year before current fiscal year	10,122		14,298
Total financing receivable, Two years before current fiscal year	12,891		12,732
Total financing receivable, Three years before current fiscal year	11,412		13,074
Total financing receivable, Four years before current fiscal year	12,676		6,242
Total financing receivable, More than five years before current fiscal year	32,253		28,638
Revolving Loans Amortized Cost Basis	233,267		224,449
Loans and leases	316,655		310,849
670-739 | Consumer portfolio | Other consumer
Financing Receivable
Total financing receivable, Current fiscal year	23,395		57,952
Total financing receivable, Fiscal year before current fiscal year	103,824		432
Total financing receivable, Two years before current fiscal year	513		372
Total financing receivable, Three years before current fiscal year	352		313
Total financing receivable, Four years before current fiscal year	238		220
Total financing receivable, More than five years before current fiscal year	213		188
Revolving Loans Amortized Cost Basis	16,803		3,349
Loans and leases	145,338		62,826
580-669 | Consumer portfolio | Residential
Financing Receivable
Total financing receivable, Current fiscal year	612		16,643
Total financing receivable, Fiscal year before current fiscal year	21,028		13,382
Total financing receivable, Two years before current fiscal year	21,521		55,507
Total financing receivable, Three years before current fiscal year	62,529		35,292
Total financing receivable, Four years before current fiscal year	44,028		16,738
Total financing receivable, More than five years before current fiscal year	119,859		109,240
Revolving Loans Amortized Cost Basis	0		0
Loans and leases	269,577		246,802
580-669 | Consumer portfolio | Home equity
Financing Receivable
Total financing receivable, Current fiscal year	261		1,755
Total financing receivable, Fiscal year before current fiscal year	1,780		2,570
Total financing receivable, Two years before current fiscal year	2,926		1,685
Total financing receivable, Three years before current fiscal year	2,867		2,172
Total financing receivable, Four years before current fiscal year	1,988		754
Total financing receivable, More than five years before current fiscal year	13,393		9,471
Revolving Loans Amortized Cost Basis	67,227		67,745
Loans and leases	90,442		86,152
580-669 | Consumer portfolio | Other consumer
Financing Receivable
Total financing receivable, Current fiscal year	556		1,417
Total financing receivable, Fiscal year before current fiscal year	2,487		116
Total financing receivable, Two years before current fiscal year	116		105
Total financing receivable, Three years before current fiscal year	104		69
Total financing receivable, Four years before current fiscal year	57		25
Total financing receivable, More than five years before current fiscal year	109		81
Revolving Loans Amortized Cost Basis	1,102		1,150
Loans and leases	4,531		2,963
579 and below | Consumer portfolio | Residential
Financing Receivable
Total financing receivable, Current fiscal year	45		237
Total financing receivable, Fiscal year before current fiscal year	750		2,680
Total financing receivable, Two years before current fiscal year	2,669		12,617
Total financing receivable, Three years before current fiscal year	14,266		21,387
Total financing receivable, Four years before current fiscal year	21,147		3,791
Total financing receivable, More than five years before current fiscal year	54,537		49,905
Revolving Loans Amortized Cost Basis	0		0
Loans and leases	93,414		90,617
579 and below | Consumer portfolio | Home equity
Financing Receivable
Total financing receivable, Current fiscal year	0		58
Total financing receivable, Fiscal year before current fiscal year	57		799
Total financing receivable, Two years before current fiscal year	1,114		2,401
Total financing receivable, Three years before current fiscal year	2,235		726
Total financing receivable, Four years before current fiscal year	680		429
Total financing receivable, More than five years before current fiscal year	3,641		4,254
Revolving Loans Amortized Cost Basis	30,247		32,429
Loans and leases	37,974		41,096
579 and below | Consumer portfolio | Other consumer
Financing Receivable
Total financing receivable, Current fiscal year	3		29
Total financing receivable, Fiscal year before current fiscal year	29		93
Total financing receivable, Two years before current fiscal year	67		63
Total financing receivable, Three years before current fiscal year	61		28
Total financing receivable, Four years before current fiscal year	23		9
Total financing receivable, More than five years before current fiscal year	26		0
Revolving Loans Amortized Cost Basis	471		569
Loans and leases	$ 680		$ 791