Bank Loans (Risk Category Of Loan Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	$ 17,761,548	$ 16,743,487
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	17,587,865	16,553,018
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	38,000	54,817
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	118,874	127,831
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	16,809	7,821
Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	6,008,507	5,482,026
Residential Mortgage | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	6,007,175	5,480,693
Residential Mortgage | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans		84
Residential Mortgage | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	1,332	1,249
Commercial And Industrial
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	7,656,507	7,345,753
Commercial And Industrial | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	7,504,185	7,193,435
Commercial And Industrial | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	38,000	38,000
Commercial And Industrial | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	98,845	107,747
Commercial And Industrial | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	15,477	6,571
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	2,954,212	2,880,158
Securities-Based Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	2,954,212	2,880,158
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	499,825	409,847
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	499,825	407,298
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans		2,548
Commercial Real Estate [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans		1
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	87,901	82,508
Home Equity Lines Of Credit [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	87,872	82,479
Home Equity Lines Of Credit [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans		29
Home Equity Lines Of Credit [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	29
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	521,623	511,084
Construction And Land [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	501,623	476,844
Construction And Land [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans		14,240
Construction And Land [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	20,000	20,000
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	32,973	32,111
Other [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	$ 32,973	$ 32,111