Bank Loans (Activity in the Allowance for Credit Losses on Loans by Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 139,308	$ 128,292
Provision	12,551	4,558
Charge-offs	(11,806)	(3,570)
Recoveries	8	933
Ending Balance	140,061	130,213
Commercial and Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	92,698	67,077
Provision	11,402	1,447
Charge-offs	(11,806)	(3,570)
Recoveries		933
Ending Balance	92,294	65,887
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	8,057	21,386
Provision	1,309	(697)
Ending Balance	9,366	20,689
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	11,061	13,855
Provision	111	(1,348)
Ending Balance	11,172	12,507
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	12,866	11,817
Provision	385	6,772
Ending Balance	13,251	18,589
Fund Banking [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	10,792	10,173
Provision	(546)	(1,410)
Ending Balance	10,246	8,763
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,917	3,035
Provision	11	33
Ending Balance	2,928	3,068
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	317	371
Provision	(147)	(125)
Ending Balance	170	246
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	600	578
Provision	26	(114)
Recoveries	8
Ending Balance	$ 634	$ 464