v3.25.2
Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Available for Sale (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Dec. 31, 2024
Schedule of Investments [Line Items]    
Debt Securities, Available-for-sale, Amortized Cost $ 18,030,136 $ 16,602,158
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax 33,543 4,845
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 1,450,993 1,563,378
Debt Securities, Available-for-sale, Allowance for Credit Loss 0 0
Securities available for sale, at estimated fair value 16,612,686 15,043,625
US Treasury Securities [Member]    
Schedule of Investments [Line Items]    
Debt Securities, Available-for-sale, Amortized Cost 3,023,961 3,692,215
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax 0 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 183,022 249,895
Debt Securities, Available-for-sale, Allowance for Credit Loss 0 0
Securities available for sale, at estimated fair value 2,840,939 3,442,320
Residential Mortgage Backed Securities [Member]    
Schedule of Investments [Line Items]    
Debt Securities, Available-for-sale, Amortized Cost 9,716,684 8,024,704
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax 31,912 2,352
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 898,333 1,029,154
Debt Securities, Available-for-sale, Allowance for Credit Loss 0 0
Securities available for sale, at estimated fair value 8,850,263 6,997,902
US States and Political Subdivisions Debt Securities [Member]    
Schedule of Investments [Line Items]    
Debt Securities, Available-for-sale, Amortized Cost 5,246,131 4,842,060
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax 1,631 2,493
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 369,638 284,329
Debt Securities, Available-for-sale, Allowance for Credit Loss 0 0
Securities available for sale, at estimated fair value 4,878,124 4,560,224
Other Investments [Member]    
Schedule of Investments [Line Items]    
Debt Securities, Available-for-sale, Amortized Cost 43,360 43,179
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax 0 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 0 0
Debt Securities, Available-for-sale, Allowance for Credit Loss 0 0
Securities available for sale, at estimated fair value $ 43,360 $ 43,179