Bank Loans (Risk Category of Loan Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 25,866,033	$ 22,066,763
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	25,382,333	21,594,679
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	177,713	145,241
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	183,090	205,690
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	122,897	121,153
Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,821,336	9,254,939
Residential Real Estate [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,809,610	9,247,024
Residential Real Estate [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,314	4,427
Residential Real Estate [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,412	3,488
Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,720,505	4,135,091
Commercial and Industrial [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,417,437	3,851,296
Commercial and Industrial [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	70,466	120,212
Commercial and Industrial [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	156,341	80,848
Commercial and Industrial [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	76,261	82,735
Fund Banking [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,719,233	4,096,649
Fund Banking [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,719,233	4,096,649
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,992,963	2,672,431
Securities-Based Loans [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,992,963	2,672,431
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	926,412	1,214,450
Construction And Land [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	840,137	1,110,498
Construction And Land [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	39,701	20,100
Construction And Land [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	0	45,434
Construction And Land [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	46,574	38,418
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	372,212	423,474
Commercial Real Estate [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	289,841	348,069
Commercial Real Estate [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	58,196
Commercial Real Estate [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	24,175	75,405
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	261,243	225,196
Home Equity Lines Of Credit [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	261,081	224,182
Home Equity Lines Of Credit [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		499
Home Equity Lines Of Credit [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	162	515
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	52,129	44,533
Other [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	52,031	44,530
Other [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	36	$ 3
Other [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 62