Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 85,833	$ 67,466
Provision	2,283	2,043
Charge-offs	(56)	(14)
Recoveries	112	2
Ending Balance	88,172	69,497
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	68,367	54,474
Provision	211	1,971
Charge-offs	(12)	(12)
Ending Balance	68,566	56,433
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	11,228	8,430
Provision	270	349
Recoveries	87
Ending Balance	11,585	8,779
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,978	2,088
Provision	249	(194)
Ending Balance	2,227	1,894
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,778	1,520
Provision	643	(200)
Ending Balance	2,421	1,320
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,241	100
Provision	483	99
Ending Balance	1,724	199
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	310	162
Provision	61	1
Recoveries	1	1
Ending Balance	372	164
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	88	16
Provision	78
Charge-offs	(44)	(2)
Recoveries	24	1
Ending Balance	146	15
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	843	676
Provision	288	17
Ending Balance	$ 1,131	$ 693