XML 61 R50.htm IDEA: XBRL DOCUMENT v3.25.1
Securities - Securities Available for Sale, with Unrealized Losses Segregated by Length of Impairment (Detail) - USD ($)
$ in Thousands
Mar. 31, 2025
Dec. 31, 2024
Schedule of Available-for-Sale Securities [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 2,152,204  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 33,178  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 11,549,481  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 1,395,997  
Debt Securities, Available-for-sale, Unrealized Loss Position 13,701,685  
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 1,429,175 $ 1,563,378
U.S. Treasury [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 0  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 0  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 3,491,195  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 204,459  
Debt Securities, Available-for-sale, Unrealized Loss Position 3,491,195  
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 204,459 249,895
Residential Mortgage Backed Securities [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 1,064,145  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 11,498  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 4,737,614  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 900,255  
Debt Securities, Available-for-sale, Unrealized Loss Position 5,801,759  
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax 911,753 1,029,154
States and political subdivisions [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 1,088,059  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 21,680  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 3,320,672  
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 291,283  
Debt Securities, Available-for-sale, Unrealized Loss Position 4,408,731  
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax $ 312,963 $ 284,329