Bank Loans (Risk Category of Loan Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	$ 20,452,389	$ 20,602,558
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	20,063,652	20,427,527
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	177,943	108,027
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	199,982	56,899
Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	10,812	10,105
Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	7,957,027	7,371,671
Residential Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	7,955,487	7,370,717
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0	266
Residential Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Residential Real Estate [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	1,540	688
Commercial and Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	4,367,671	4,897,176
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	4,122,791	4,743,290
Commercial and Industrial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	75,483	87,761
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	160,164	56,899
Commercial and Industrial [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	9,233	9,226
Fund Banking [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	4,114,889	4,182,641
Fund Banking [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	4,114,889	4,182,641
Fund Banking [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Fund Banking [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Fund Banking [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Securities-Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	2,317,631	2,724,551
Securities-Based Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	2,317,629	2,724,548
Securities-Based Loans [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Securities-Based Loans [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Securities-Based Loans [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	2	3
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	670,907	675,599
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	553,124	655,599
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	77,979	20,000
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	39,804
Construction and Land [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	851,709	593,191
Construction and Land [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	827,228	593,191
Construction and Land [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	24,481
Construction and Land [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Construction and Land [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Home Equity Lines of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	123,995	107,136
Home Equity Lines of Credit [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	123,973	106,954
Home Equity Lines of Credit [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Home Equity Lines of Credit [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Home Equity Lines of Credit [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	22	182
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	48,560	50,593
Other [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	48,531	50,587
Other [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	0
Other [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	14
Other [Member] | Doubtful [Member]
Financing Receivable Recorded Investment [Line Items]
Gross bank loans	$ 15	$ 6