Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 45,163	$ 29,787
Provision	6,136	4,259
Charge-offs	(1)
Recoveries		4
Ending Balance	51,298	34,050
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	35,127	24,748
Provision	3,662	2,952
Ending Balance	38,789	27,700
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	3,094	1,607
Provision	299	(2)
Ending Balance	3,393	1,605
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	129	105
Provision	(22)	(21)
Ending Balance	107	84
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,660	1,241
Provision	1,530	88
Recoveries		1
Ending Balance	4,190	1,330
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,363	264
Provision	255	1,022
Recoveries		3
Ending Balance	1,618	1,289
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	371	290
Provision	(85)	(23)
Charge-offs	(1)
Ending Balance	285	267
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	232	78
Provision	205	40
Ending Balance	437	118
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,187	1,454
Provision	292	203
Ending Balance	$ 2,479	$ 1,657