Bank Loans (Activity In The Allowance For Loan Losses By Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 115,821	$ 90,472	$ 95,579	$ 85,833
CECL Adoption			(11,736)
Provision	(1,777)	929	30,369	5,565
Charge-offs	(23)	(56)	(193)	(166)
Recoveries	92	15	94	128
Ending Balance	114,113	91,360	114,113	91,360
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	65,503	69,263	69,949	68,367
CECL Adoption			(19,940)
Provision	10,303	(1,070)	25,949	(116)
Charge-offs	(1)	(21)	(153)	(79)
Recoveries	4		4
Ending Balance	75,809	68,172	75,809	68,172
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	24,043	12,042	14,253	11,228
CECL Adoption			3,499
Provision	(6,360)	519	(69)	1,246
Recoveries		1		88
Ending Balance	17,683	12,562	17,683	12,562
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,807	2,311	2,361	1,978
CECL Adoption			1,346
Provision	95	(130)	(1,805)	203
Ending Balance	1,902	2,181	1,902	2,181
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	10,647	2,478	3,564	1,778
CECL Adoption			791
Provision	(2,730)	425	3,562	1,125
Ending Balance	7,917	2,903	7,917	2,903
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	13,075	2,402	4,613	1,241
CECL Adoption			2,674
Provision	(2,889)	865	2,899	2,026
Ending Balance	10,186	3,267	10,186	3,267
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	499	421	442	310
CECL Adoption			39
Provision	(205)	13	(188)	123
Recoveries	87	1	88	2
Ending Balance	381	435	381	435
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	247	179	194	88
CECL Adoption			58
Provision	9	38	21	156
Charge-offs	(22)	(35)	(40)	(87)
Recoveries	1	13	2	38
Ending Balance	$ 235	195	235	195
Unallocated [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance		1,376	203	843
CECL Adoption			$ (203)
Provision		269		802
Ending Balance		$ 1,645		$ 1,645

Loans and leases receivable allowance impact of current expected credit loss adoption.

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Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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