Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 95,579	$ 85,833
CECL Adoption	(11,736)
Provision	18,978	2,283
Charge-offs	(20)	(56)
Recoveries	1	112
Ending Balance	102,802	88,172
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	69,949	68,367
CECL Adoption	(19,940)
Provision	9,955	211
Charge-offs	(2)	(12)
Ending Balance	59,962	68,566
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	14,253	11,228
CECL Adoption	3,499
Provision	2,233	270
Recoveries		87
Ending Balance	19,985	11,585
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,361	1,978
CECL Adoption	1,346
Provision	(792)	249
Ending Balance	2,915	2,227
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	3,564	1,778
CECL Adoption	791
Provision	3,810	643
Ending Balance	8,165	2,421
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	4,613	1,241
CECL Adoption	2,674
Provision	3,666	483
Ending Balance	10,953	1,724
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	442	310
CECL Adoption	39
Provision	57	61
Recoveries	1	1
Ending Balance	539	372
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	194	88
CECL Adoption	58
Provision	49	78
Charge-offs	(18)	(44)
Recoveries		24
Ending Balance	283	146
Unallocated [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	203	843
CECL Adoption	$ (203)
Provision		288
Ending Balance		$ 1,131