Bank Loans (Risk Category Of Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 11,170,813	$ 9,752,616
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	10,824,109	9,676,864
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	130,332	49,244
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	202,728	13,568
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	13,644	12,940
Commercial And Industrial
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,296,089	3,438,953
Commercial And Industrial | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,995,351	3,365,800
Commercial And Industrial | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	105,759	48,241
Commercial And Industrial | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	182,728	11,972
Commercial And Industrial | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,251	12,940
Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,956,670	3,309,548
Residential Mortgage | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,955,421	3,307,719
Residential Mortgage | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		417
Residential Mortgage | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		1,412
Residential Mortgage | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,249
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,933,974	2,098,211
Securities-Based Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,933,974	2,098,211
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	366,485	428,549
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	356,008	427,963
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	10,333	586
Commercial Real Estate [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	144
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	501,681	398,839
Construction And Land [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	467,441	398,839
Construction And Land [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	14,240
Construction And Land [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	20,000
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	75,507	51,205
Home Equity Lines Of Credit [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	75,507	51,021
Home Equity Lines Of Credit [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		184
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	40,407	27,311
Other [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 40,407	$ 27,311