Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 85,833	$ 67,466
Provision	9,977	18,366
Charge-offs	(386)	(14)
Recoveries	155	15
Ending Balance	95,579	85,833
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	68,367	54,474
Provision	1,821	13,896
Charge-offs	(239)	(12)
Recoveries		9
Ending Balance	69,949	68,367
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	11,228	8,430
Provision	2,974	2,798
Charge-offs	(41)
Recoveries	92
Ending Balance	14,253	11,228
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,978	2,088
Provision	383	(110)
Ending Balance	2,361	1,978
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,778	1,520
Provision	1,786	258
Ending Balance	3,564	1,778
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,241	100
Provision	3,372	1,141
Ending Balance	4,613	1,241
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	310	162
Provision	129	145
Recoveries	3	3
Ending Balance	442	310
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	88	16
Provision	152	71
Charge-offs	(106)	(2)
Recoveries	60	3
Ending Balance	194	88
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	843	676
Provision	(640)	167
Ending Balance	$ 203	$ 843