Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 73,775	$ 54,202	$ 67,466	$ 45,163
Provision	6,924	7,990	13,244	19,980
Charge-offs			(14)	(2,953)
Recoveries	1	37	4	39
Ending Balance	80,700	62,229	80,700	62,229
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	59,572	40,805	54,474	35,127
Provision	5,008	6,312	10,118	12,239
Charge-offs			(12)	(250)
Recoveries		35		36
Ending Balance	64,580	47,152	64,580	47,152
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,928	3,600	2,088	3,094
Provision	(5)	(288)	(165)	218
Ending Balance	1,923	3,312	1,923	3,312
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	9,328	5,569	8,430	2,660
Provision	1,165	1,566	2,063	4,475
Ending Balance	10,493	7,135	10,493	7,135
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,672	932	1,520	1,363
Provision	90	95	242	2,367
Charge-offs				(2,703)
Ending Balance	1,762	1,027	1,762	1,027
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	229	283	162	371
Provision		(13)	65	(102)
Recoveries		1	2	2
Ending Balance	229	271	229	271
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	303	224	100	232
Provision	600	9	803	1
Ending Balance	903	233	903	233
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	13	105	16	129
Provision	(3)	(3)	(5)	(27)
Charge-offs			(2)
Recoveries	1	1	2	1
Ending Balance	11	103	11	103
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	730	2,684	676	2,187
Provision	69	312	123	809
Ending Balance	$ 799	$ 2,996	$ 799	$ 2,996