Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 112,029	$ 95,579
CECL Adoption		(11,736)
Provision	(3,427)	18,978
Charge-offs	(934)	(20)
Recoveries		1
Ending Balance	107,668	102,802
Commercial And Industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	67,222	69,949
CECL Adoption		(19,940)
Provision	(9,972)	9,955
Charge-offs	(934)	(2)
Ending Balance	56,316	59,962
Residential Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	16,300	14,253
CECL Adoption		3,499
Provision	365	2,233
Ending Balance	16,665	19,985
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	2,015	2,361
CECL Adoption		1,346
Provision	154	(792)
Ending Balance	2,169	2,915
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	8,580	3,564
CECL Adoption		791
Provision	4,480	3,810
Ending Balance	13,060	8,165
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	17,275	4,613
CECL Adoption		2,674
Provision	1,598	3,666
Ending Balance	18,873	10,953
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	374	442
CECL Adoption		39
Provision	(33)	57
Recoveries		1
Ending Balance	341	539
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	263	397
CECL Adoption		(145)
Provision	(19)	49
Charge-offs		(18)
Ending Balance	$ 244	$ 283