Bank Loans (Risk Category of Loan Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 21,177,141	$ 20,879,745
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	20,656,659	20,349,043
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	199,349	173,237
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	176,064	213,523
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	145,069	143,942
Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,085,945	8,565,193
Residential Real Estate [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,072,915	8,557,320
Residential Real Estate [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	529	3,600
Residential Real Estate [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,501	4,273
Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,760,005	4,062,029
Commercial and Industrial [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,479,761	3,662,866
Commercial and Industrial [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	130,925	169,637
Commercial and Industrial [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	43,478	152,515
Commercial and Industrial [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	105,841	77,011
Fund Banking [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,881,895	3,854,222
Fund Banking [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,881,895	3,854,222
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,565,897	2,389,593
Securities-Based Loans [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,565,897	2,389,593
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,166,895	1,242,002
Construction And Land [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,062,495	1,200,590
Construction And Land [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	20,100
Construction And Land [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	45,155
Construction And Land [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	39,145	41,412
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	437,570	518,923
Commercial Real Estate [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	316,396	437,062
Commercial Real Estate [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	47,748
Commercial Real Estate [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	73,426	56,420
Commercial Real Estate [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		25,441
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	218,320	193,850
Home Equity Lines Of Credit [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	216,794	193,535
Home Equity Lines Of Credit [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	22
Home Equity Lines Of Credit [Member] \| Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,504	315
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	60,614	53,933
Other [Member] \| Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	60,506	53,855
Other [Member] \| Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	25
Other [Member] \| Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 83	$ 78