Bank Loans (Risk Category Of Loan Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 13,631,287	$ 11,170,813
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	13,380,137	10,824,109
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	105,330	130,332
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	137,733	202,728
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	8,087	13,644
Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,952,372	3,956,670
Residential Mortgage | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,951,039	3,955,421
Residential Mortgage | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	84
Residential Mortgage | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,249	1,249
Commercial And Industrial
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	5,033,313	4,296,089
Commercial And Industrial | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,824,500	3,995,351
Commercial And Industrial | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	91,090	105,759
Commercial And Industrial | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	110,918	182,728
Commercial And Industrial | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,805	12,251
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,581,705	1,933,974
Securities-Based Loans [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,581,705	1,933,974
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	369,502	366,485
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	362,738	356,008
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		10,333
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,731
Commercial Real Estate [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	33	144
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	82,230	75,507
Home Equity Lines Of Credit [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	82,230	75,507
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	576,362	501,681
Construction And Land [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	542,122	467,441
Construction And Land [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	14,240	14,240
Construction And Land [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	20,000	20,000
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	35,803	40,407
Other [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 35,803	$ 40,407