Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 90,472	$ 73,775	$ 85,833	$ 67,466
Provision	929	6,924	5,565	13,244
Charge-offs	(56)		(166)	(14)
Recoveries	15	1	128	4
Ending Balance	91,360	80,700	91,360	80,700
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	69,263	59,572	68,367	54,474
Provision	(1,070)	5,008	(116)	10,118
Charge-offs	(21)		(79)	(12)
Ending Balance	68,172	64,580	68,172	64,580
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	12,042	9,328	11,228	8,430
Provision	519	1,165	1,246	2,063
Recoveries	1		88
Ending Balance	12,562	10,493	12,562	10,493
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,311	1,928	1,978	2,088
Provision	(130)	(5)	203	(165)
Ending Balance	2,181	1,923	2,181	1,923
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,478	1,672	1,778	1,520
Provision	425	90	1,125	242
Ending Balance	2,903	1,762	2,903	1,762
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,402	303	1,241	100
Provision	865	600	2,026	803
Ending Balance	3,267	903	3,267	903
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	421	229	310	162
Provision	13		123	65
Recoveries	1		2	2
Ending Balance	435	229	435	229
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	179	13	88	16
Provision	38	(3)	156	(5)
Charge-offs	(35)		(87)	(2)
Recoveries	13	1	38	2
Ending Balance	195	11	195	11
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,376	730	843	676
Provision	269	69	802	123
Ending Balance	$ 1,645	$ 799	$ 1,645	$ 799