Bank Loans (Schedule Of Balance And Associated Percentage Of Each Major Loan Category In Bank Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 8,581,647	$ 7,014,421
Unamortized loan premium/(discount), net	(12,155)	788
Loans in process	27,984	(856)
Unamortized loan fees, net	5,972	872
Allowance for loan losses	(85,833)	(67,466)	$ (45,163)
Bank loans, net	$ 8,517,615	$ 6,947,759
Gross bank loans, Percent	100.00%	100.00%
Commercial And Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 3,304,234	$ 2,437,938
Allowance for loan losses	$ (68,367)	$ (54,474)	(35,127)
Gross bank loans, Percent	38.50%	34.80%
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 2,875,014	$ 2,593,576
Allowance for loan losses	$ (11,228)	$ (8,430)	(2,660)
Gross bank loans, Percent	33.50%	37.00%
Securities-Based Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 1,786,966	$ 1,819,206
Allowance for loan losses	$ (1,978)	$ (2,088)	(3,094)
Gross bank loans, Percent	20.80%	25.90%
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 318,961	$ 116,258
Allowance for loan losses	$ (1,778)	$ (1,520)	(1,363)
Gross bank loans, Percent	3.70%	1.70%
Construction And Land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 138,245	$ 7,896
Allowance for loan losses	$ (1,241)	$ (100)	(232)
Gross bank loans, Percent	1.60%	0.10%
Home Equity Lines Of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 38,098	$ 15,039
Allowance for loan losses	$ (310)	$ (162)	(371)
Gross bank loans, Percent	0.40%	0.20%
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross bank loans	$ 120,129	$ 24,508
Allowance for loan losses	$ (88)	$ (16)	$ (129)
Gross bank loans, Percent	1.50%	0.30%

Loans and leases payable receivable loans in process.

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Percentage of loans and leases receivable gross carrying amount.

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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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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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