Bank Loans (Risk Category of Loan Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 21,963,460	$ 22,066,763
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	21,441,428	21,594,679
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	162,352	145,241
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	260,291	205,690
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	99,389	121,153
Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,363,547	9,254,939
Residential Real Estate [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,350,966	9,247,024
Residential Real Estate [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,099	4,427
Residential Real Estate [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,482	3,488
Fund Banking [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,737,366	4,096,649
Fund Banking [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,737,366	4,096,649
Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,170,090	4,135,091
Commercial and Industrial [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,879,305	3,851,296
Commercial and Industrial [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	83,152	120,212
Commercial and Industrial [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	146,196	80,848
Commercial and Industrial [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	61,437	82,735
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,749,987	2,672,431
Securities-Based Loans [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,749,987	2,672,431
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,229,903	1,214,450
Construction And Land [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,087,585	1,110,498
Construction And Land [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	58,932	20,100
Construction And Land [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	45,434	45,434
Construction And Land [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	37,952	38,418
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	440,993	423,474
Commercial Real Estate [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	365,294	348,069
Commercial Real Estate [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	13,642
Commercial Real Estate [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	62,057	75,405
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	233,334	225,196
Home Equity Lines Of Credit [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	232,701	224,182
Home Equity Lines Of Credit [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	511	499
Home Equity Lines Of Credit [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	122	515
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	38,240	44,533
Other [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	38,224	44,530
Other [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 16	$ 3