Bank Loans (Aging of Recorded Investment in Past Due Loans) (Details) - USD ($)		Sep. 30, 2023		Dec. 31, 2022
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		$ 16,002,000		$ 12,612,000
Total		20,452,389,000		20,602,558,000
Non-Accrual		49,647,000	[1]	10,102,000	[2]
Restructured		146,000	[1]	150,000	[2]
Nonperforming loans with no allowance		926,000	[1]	0	[2]
Total		50,719,000	[1]	10,252,000	[2]
Loans past due 90 days and still accruing interest		0		0
30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		5,176,000		2,510,000
90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		10,826,000		10,102,000
Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		20,436,387,000		20,589,946,000
Residential Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		6,612,000		3,133,000
Total		7,957,027,000		7,371,671,000
Non-Accrual		616,000	[1]	870,000	[2]
Restructured		146,000	[1]	150,000	[2]
Nonperforming loans with no allowance		924,000	[1]	0	[2]
Total		1,686,000	[1]	1,020,000	[2]
Residential Real Estate [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		5,072,000		2,445,000
Residential Real Estate [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,540,000		688,000
Residential Real Estate [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		7,950,415,000		7,368,538,000
Commercial and Industrial [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		9,233,000		9,226,000
Total		4,367,671,000		4,897,176,000
Non-Accrual		9,233,000	[1]	9,226,000	[2]
Restructured	[1]	0
Nonperforming loans with no allowance	[1]	0
Total		9,233,000	[1]	9,226,000	[2]
Commercial and Industrial [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Commercial and Industrial [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		9,233,000		9,226,000
Commercial and Industrial [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		4,358,438,000		4,887,950,000
Fund Banking [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Total		4,114,889,000		4,182,641,000
Fund Banking [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Fund Banking [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Fund Banking [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		4,114,889,000		4,182,641,000
Securities-Based Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Total		2,317,631,000		2,724,551,000
Securities-Based Loans [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Securities-Based Loans [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Securities-Based Loans [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		2,317,631,000		2,724,551,000
Commercial Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Total		670,907,000		675,599,000
Non-Accrual	[1]	39,747,000
Restructured	[1]	0
Nonperforming loans with no allowance	[1]	0
Total	[1]	39,747,000
Commercial Real Estate [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Commercial Real Estate [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Commercial Real Estate [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		670,907,000		675,599,000
Construction and Land [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Total		851,709,000		593,191,000
Construction and Land [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0
Construction and Land [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		0		0
Construction and Land [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		851,709,000		593,191,000
Home Equity Lines of Credit [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		73,000		211,000
Total		123,995,000		107,136,000
Non-Accrual	[1]	22,000
Restructured	[1]	0
Nonperforming loans with no allowance	[1]	0
Total	[1]	22,000
Home Equity Lines of Credit [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		51,000		29,000
Home Equity Lines of Credit [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		22,000		182,000
Home Equity Lines of Credit [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		123,922,000		106,925,000
Other [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		84,000		42,000
Total		48,560,000		50,593,000
Non-Accrual		29,000	[1]	6,000	[2]
Restructured	[1]	0
Nonperforming loans with no allowance		2,000	[1]	0	[2]
Total		31,000	[1]	6,000	[2]
Other [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		53,000		36,000
Other [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		31,000		6,000
Other [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		$ 48,476,000		$ 50,551,000

[1] There were no loans past due 90 days and still accruing interest at September 30, 2023.

[2] There were no loans past due 90 days and still accruing interest at December 31, 2022.