Bank Loans (Risk Category Of Loan Portfolio) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 12,898,807	$ 11,170,813
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,586,626	10,824,109
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	107,046	130,332
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	196,754	202,728
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	8,381	13,644
Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,567,467	3,956,670
Residential Mortgage | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,562,689	3,955,421
Residential Mortgage | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,381
Residential Mortgage | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,148
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	4,950,516	4,296,089
Commercial And Industrial | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	4,708,163	3,995,351
Commercial And Industrial | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	68,006	105,759
Commercial And Industrial | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	167,251	182,728
Commercial And Industrial | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	7,096	12,251
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,331,737	1,933,974
Securities-Based Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	2,331,737	1,933,974
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	370,517	366,485
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	339,707	356,008
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	22,419	10,333
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	8,355
Commercial Real Estate [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	36	144
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	76,839	75,507
Home Equity Lines Of Credit [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	76,839	75,507
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	563,552	501,681
Construction And Land [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	529,312	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	38,179	40,407
Other [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 38,179	$ 40,407