v3.26.1
Bank Loans (Aging of the Recorded Investment in Past Due Loans) (Details) - USD ($)
Mar. 31, 2026
Dec. 31, 2025
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans $ 21,963,460,000 $ 22,066,763,000
Nonperforming loans with allowance 62,807,000 81,465,000
Nonperforming loans with no allowance 43,186,000 43,694,000
Total 105,993,000 125,159,000
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 gross bank loans 55,311,000 70,094,000
90 or More Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 99,713,000 [1] 104,676,000 [2]
Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 155,024,000 174,770,000
Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 21,808,436,000 21,891,993,000
Residential Real Estate [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 9,363,547,000 9,254,939,000
Nonperforming loans with allowance 3,656,000 1,033,000
Nonperforming loans with no allowance 2,826,000 2,455,000
Total 6,482,000 3,488,000
Residential Real Estate [Member] | 30 - 89 Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 16,759,000 16,269,000
Residential Real Estate [Member] | 90 or More Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 6,482,000 [1] 3,488,000 [2]
Residential Real Estate [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 23,241,000 19,757,000
Residential Real Estate [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 9,340,306,000 9,235,182,000
Commercial and Industrial [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 4,170,090,000 4,135,091,000
Nonperforming loans with allowance 59,151,000 80,429,000
Nonperforming loans with no allowance 2,286,000 2,307,000
Total 61,437,000 82,736,000
Commercial and Industrial [Member] | 30 - 89 Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 34,747,000 51,000,000
Commercial and Industrial [Member] | 90 or More Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 47,675,000 [1] 55,236,000 [2]
Commercial and Industrial [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 82,422,000 106,236,000
Commercial and Industrial [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 4,087,668,000 4,028,855,000
Fund Banking [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 3,737,366,000 4,096,649,000
Fund Banking [Member] | 30 - 89 Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 2,835,000 1,774,000
Fund Banking [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 2,835,000 1,774,000
Fund Banking [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 3,734,531,000 4,094,875,000
Securities-Based Loans [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 2,749,987,000 2,672,431,000
Securities-Based Loans [Member] | 30 - 89 Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 362,000 514,000
Securities-Based Loans [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 362,000 514,000
Securities-Based Loans [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 2,749,625,000 2,671,917,000
Construction And Land [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 1,229,903,000 1,214,450,000
Nonperforming loans with no allowance 37,952,000 38,417,000
Total 37,952,000 38,417,000
Construction And Land [Member] | 90 or More Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 45,434,000 [1] 45,434,000 [2]
Construction And Land [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 45,434,000 45,434,000
Construction And Land [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 1,184,469,000 1,169,016,000
Commercial Real Estate [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 440,993,000 423,474,000
Commercial Real Estate [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 440,993,000 423,474,000
Home Equity Lines Of Credit [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 233,334,000 225,196,000
Nonperforming loans with no allowance 122,000 515,000
Total 122,000 515,000
Home Equity Lines Of Credit [Member] | 30 - 89 Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 525,000 499,000
Home Equity Lines Of Credit [Member] | 90 or More Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 122,000 [1] 515,000 [2]
Home Equity Lines Of Credit [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 647,000 1,014,000
Home Equity Lines Of Credit [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 232,687,000 224,182,000
Other [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 38,240,000 44,533,000
Nonperforming loans with allowance   3,000
Total   3,000
Other [Member] | 30 - 89 Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 83,000 38,000
Other [Member] | 90 or More Days Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans [2]   3,000
Other [Member] | Financial Asset, Past Due [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans 83,000 41,000
Other [Member] | Current Balance [Member]    
Financing Receivable Recorded Investment Past Due [Line Items]    
Total gross bank loans $ 38,157,000 $ 44,492,000
[1] There were no loans past due 90 days and still accruing interest at March 31, 2026.
[2] There were no loans past due 90 days and still accruing interest at December 31, 2025.