Bank Loans (Aging of the Recorded Investment in Past Due Loans) (Details) - USD ($)		Mar. 31, 2025		Dec. 31, 2024
Financing Receivable Recorded Investment Past Due [Line Items]
Total		$ 20,372,268,000		$ 20,879,745,000
Non-accrual		116,232,000	[1]	77,966,000	[2]
Nonperforming loans with no allowance		44,659,000	[1]	82,934,000	[2]
Total		160,891,000	[1]	160,900,000	[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		85,052,000		72,100,000
90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		85,017,000		31,856,000
Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		170,069,000		103,956,000
Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		20,202,199,000		20,775,789,000
Residential Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		8,699,229,000		8,565,193,000
Non-accrual		3,409,000	[1]	1,433,000	[2]
Nonperforming loans with no allowance		2,840,000	[1]	2,463,000	[2]
Total		6,249,000	[1]	3,896,000	[2]
Residential Real Estate [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		11,311,000		12,057,000
Residential Real Estate [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		6,249,000		4,273,000
Residential Real Estate [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		17,560,000		16,330,000
Residential Real Estate [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		8,681,669,000		8,548,863,000
Commercial and Industrial [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,678,411,000		4,062,029,000
Non-accrual		112,359,000	[1]	76,254,000	[2]
Nonperforming loans with no allowance		756,000	[1]	13,504,000	[2]
Total		113,115,000	[1]	89,758,000	[2]
Commercial and Industrial [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		66,273,000		59,396,000
Commercial and Industrial [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		78,020,000		27,190,000
Commercial and Industrial [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		144,293,000		86,586,000
Commercial and Industrial [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,534,118,000		3,975,443,000
Fund Banking [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,659,294,000		3,854,222,000
Fund Banking [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		7,000,000
Fund Banking [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		7,000,000
Fund Banking [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,652,294,000		3,854,222,000
Securities-Based Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		2,404,960,000		2,389,593,000
Securities-Based Loans [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		115,000
Securities-Based Loans [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		115,000
Securities-Based Loans [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		230,000
Securities-Based Loans [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		2,404,730,000		2,389,593,000
Construction And Land [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		1,206,876,000		1,242,002,000
Nonperforming loans with no allowance		40,894,000	[1]	41,412,000	[2]
Total		40,894,000	[1]	41,412,000	[2]
Construction And Land [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		1,206,876,000		1,242,002,000
Commercial Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		472,550,000		518,923,000
Nonperforming loans with no allowance	[2]			25,441,000
Total	[2]			25,441,000
Commercial Real Estate [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		472,550,000		518,923,000
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		195,811,000		193,850,000
Non-accrual		411,000	[1]	201,000	[2]
Nonperforming loans with no allowance		142,000	[1]	114,000	[2]
Total		553,000	[1]	315,000	[2]
Home Equity Lines Of Credit [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		352,000		640,000
Home Equity Lines Of Credit [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		553,000		315,000
Home Equity Lines Of Credit [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		905,000		955,000
Home Equity Lines Of Credit [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		194,906,000		192,895,000
Other [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		55,137,000		53,933,000
Non-accrual		53,000	[1]	78,000	[2]
Nonperforming loans with no allowance	[1]	27,000
Total		80,000	[1]	78,000	[2]
Other [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		1,000		7,000
Other [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		80,000		78,000
Other [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		81,000		85,000
Other [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		$ 55,056,000		$ 53,848,000

[1] There were no loans past due 90 days and still accruing interest at March 31, 2025

[2] There were no loans past due 90 days and still accruing interest at December 31, 2024.