Bank Loans (Activity in Allowance for Loan Losses by Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 122,681	$ 107,482	$ 111,653	$ 99,344
Provision	13,418	1,550	24,911	9,722
Charge-offs	(302)	(4,008)	(920)	(4,044)
Recoveries	0	0	153	2
Ending Balance	135,797	105,024	135,797	105,024
Commercial and Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	66,377	57,594	54,143	44,661
Provision	8,584	(1,511)	21,283	11,420
Charge-offs	(302)	(4,008)	(920)	(4,008)
Recoveries	0	0	153	2
Ending Balance	74,659	52,075	74,659	52,075
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	13,429	6,483	12,897	3,934
Provision	6,437	5,480	6,969	8,029
Charge-offs	0		0
Recoveries	0		0
Ending Balance	19,866	11,963	19,866	11,963
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	14,413	22,615	20,441	28,560
Provision	194	(5,150)	(5,834)	(11,095)
Charge-offs	0		0
Recoveries	0		0
Ending Balance	14,607	17,465	14,607	17,465
Fund Banking [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	12,178	9,758	11,711	8,868
Provision	(660)	2,414	(193)	3,304
Charge-offs	0		0
Recoveries	0		0
Ending Balance	11,518	12,172	11,518	12,172
Construction and Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	12,645	5,854	8,568	8,536
Provision	(1,145)	1,675	2,932	(1,007)
Charge-offs	0		0
Recoveries	0		0
Ending Balance	11,500	7,529	11,500	7,529
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	3,086	3,976	3,157	4,006
Provision	(68)	(658)	(139)	(652)
Charge-offs	0		0	(36)
Recoveries	0		0
Ending Balance	3,018	3,318	3,018	3,318
Home Equity Lines of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	168	922	364	511
Provision	27	(724)	(169)	(313)
Charge-offs	0		0
Recoveries	0		0
Ending Balance	195	198	195	198
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	385	280	372	268
Provision	49	24	62	36
Charge-offs	0		0
Recoveries	0		0
Ending Balance	$ 434	$ 304	$ 434	$ 304