Bank Loans (Unpaid Principal Balances Of Loans and Amount Of Allowance Allocated Based Upon Impairment Method by Portfolio Segment) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	$ 8,182	$ 8,703
Allowance for Loan Losses, Collectively Evaluated for Impairment	87,397	77,130
Allowance for Loan Losses, Total	95,579	85,833	$ 67,466
Recorded Investment in Loans, Individually Evaluated for Impairment	14,587	24,401
Recorded Investment in Loans, Collectively Evaluated for Impairment	9,738,029	8,557,246
Recorded Investment in Loans, Total	9,752,616	8,581,647
Commercial And Industrial [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	8,158	8,678
Allowance for Loan Losses, Collectively Evaluated for Impairment	61,791	59,689
Allowance for Loan Losses, Total	69,949	68,367	54,474
Recorded Investment in Loans, Individually Evaluated for Impairment	12,991	23,677
Recorded Investment in Loans, Collectively Evaluated for Impairment	3,425,962	3,280,557
Recorded Investment in Loans, Total	3,438,953	3,304,234
Residential Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	24	24
Allowance for Loan Losses, Collectively Evaluated for Impairment	14,229	11,204
Allowance for Loan Losses, Total	14,253	11,228	8,430
Recorded Investment in Loans, Individually Evaluated for Impairment	1,412	519
Recorded Investment in Loans, Collectively Evaluated for Impairment	3,308,136	2,874,495
Recorded Investment in Loans, Total	3,309,548	2,875,014
Securities-Based Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	2,361	1,978
Allowance for Loan Losses, Total	2,361	1,978	2,088
Recorded Investment in Loans, Collectively Evaluated for Impairment	2,098,211	1,786,966
Recorded Investment in Loans, Total	2,098,211	1,786,966
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	3,564	1,778
Allowance for Loan Losses, Total	3,564	1,778	1,520
Recorded Investment in Loans, Collectively Evaluated for Impairment	428,549	318,961
Recorded Investment in Loans, Total	428,549	318,961
Construction And Land [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	4,613	1,241
Allowance for Loan Losses, Total	4,613	1,241	100
Recorded Investment in Loans, Collectively Evaluated for Impairment	398,839	138,245
Recorded Investment in Loans, Total	398,839	138,245
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	442	310
Allowance for Loan Losses, Total	442	310	162
Recorded Investment in Loans, Individually Evaluated for Impairment	184	184
Recorded Investment in Loans, Collectively Evaluated for Impairment	51,021	37,914
Recorded Investment in Loans, Total	51,205	38,098
Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		1
Allowance for Loan Losses, Collectively Evaluated for Impairment	194	87
Allowance for Loan Losses, Total	194	88	16
Recorded Investment in Loans, Individually Evaluated for Impairment		21
Recorded Investment in Loans, Collectively Evaluated for Impairment	27,311	120,108
Recorded Investment in Loans, Total	27,311	120,129
Qualitative [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment	203	843
Allowance for Loan Losses, Total	$ 203	$ 843	$ 676

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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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 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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