Bank Loans (Aging of the Recorded Investment in Past Due Loans) (Details) - USD ($)		Dec. 31, 2024		Dec. 31, 2023
Financing Receivable Recorded Investment Past Due [Line Items]
Total		$ 20,879,745,000		$ 19,441,467,000
Non-accrual		77,966,000	[1]	42,366,000	[2]
Nonperforming loans with no allowance		82,934,000	[1]	3,090,000	[2]
Total		160,900,000	[1]	45,456,000	[2]
Loans past due 90 days and still accruing interest		0		0
Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		103,956,000		22,043,000
30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		72,100,000		15,927,000
90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		31,856,000		6,116,000
Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		20,775,789,000		19,419,424,000
Residential Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		8,565,193,000		8,047,647,000
Non-accrual		1,433,000	[1]	3,090,000	[2]
Nonperforming loans with no allowance		2,463,000	[1]	1,000,000	[2]
Total		3,896,000	[1]	4,090,000	[2]
Residential Real Estate [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		16,330,000		19,257,000
Residential Real Estate [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		12,057,000		15,312,000
Residential Real Estate [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		4,273,000		3,945,000
Residential Real Estate [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		8,548,863,000		8,028,390,000
Commercial and Industrial [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		4,062,029,000		3,566,987,000
Non-accrual	[1]	76,254,000
Nonperforming loans with no allowance		13,504,000	[1]	2,022,000	[2]
Total		89,758,000	[1]	2,022,000	[2]
Commercial and Industrial [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		86,586,000		2,022,000
Commercial and Industrial [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		59,396,000
Commercial and Industrial [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		27,190,000		2,022,000
Commercial and Industrial [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,975,443,000		3,564,965,000
Fund Banking [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,854,222,000		3,633,126,000
Fund Banking [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		3,854,222,000		3,633,126,000
Securities-Based Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		2,389,593,000		2,306,455,000
Nonperforming loans with no allowance	[2]			3,000
Total	[2]			3,000
Securities-Based Loans [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total				3,000
Securities-Based Loans [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total				3,000
Securities-Based Loans [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		2,389,593,000		2,306,452,000
Construction And Land [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		1,242,002,000		1,034,370,000
Nonperforming loans with no allowance	[1]	41,412,000
Total	[1]	41,412,000
Construction And Land [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		1,242,002,000		1,034,370,000
Commercial Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		518,923,000		660,631,000
Non-accrual	[2]			39,195,000
Nonperforming loans with no allowance	[1]	25,441,000
Total		25,441,000	[1]	39,195,000	[2]
Commercial Real Estate [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		518,923,000		660,631,000
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		193,850,000		136,270,000
Non-accrual		201,000	[1]	22,000	[2]
Nonperforming loans with no allowance		114,000	[1]	65,000	[2]
Total		315,000	[1]	87,000	[2]
Home Equity Lines Of Credit [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		955,000		657,000
Home Equity Lines Of Credit [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		640,000		570,000
Home Equity Lines Of Credit [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		315,000		87,000
Home Equity Lines Of Credit [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		192,895,000		135,613,000
Other [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		53,933,000		55,981,000
Non-accrual		78,000	[1]	59,000	[2]
Total		78,000	[1]	59,000	[2]
Other [Member] | Financial Asset, Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		85,000		104,000
Other [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		7,000		45,000
Other [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		78,000		59,000
Other [Member] | Current Balance [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total		$ 53,848,000		$ 55,877,000

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

[2] There were no loans past due 90 days and still accruing interest at December 31, 2023.