v3.26.3
Investment Securities, AFS and HTM Contractual Maturities (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Amortized Cost    
Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One $ 4,750  
Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five 6,243  
Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 0  
Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 2,606  
Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Amortized Cost 13,599  
Available for Sale, Total debt securities 6,443,528 $ 5,367,813
Fair Value    
Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One 3,059  
Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five 6,002  
Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 0  
Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 2,385  
Debt Securities, Available-for-Sale, Maturity, without Single Maturity Date, Fair Value 11,446  
Available for Sale, Total debt securities $ 6,198,828 5,397,563
Ratio of Fair Value to Amortized Cost, AFS 96.20%  
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Year One $ 7,118  
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year One through Five 90,248  
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 5 through 10 333,317  
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, after Year 10 1,147,141  
Held to Maturity, Total Debt Securities 1,577,824  
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 3,462,220 3,602,576
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, Year One 7,080  
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five 87,290  
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 302,799  
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 908,585  
Held to Maturity, Securities, Debt Securities 1,305,754  
Debt Securities, Held-to-Maturity, Fair Value $ 2,804,882 3,190,994
Ratio of Fair Value to Amortized Cost, HTM 81.00%  
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Amortized Cost    
Available for Sale, Total debt securities $ 0  
Fair Value    
Available for Sale, Total debt securities 0  
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 284,928 302,817
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value 224,916 258,827
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]    
Amortized Cost    
Available for Sale, Total debt securities 86,587 95,977
Fair Value    
Available for Sale, Total debt securities 86,048 95,046
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 0  
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value 0  
US Government-sponsored Enterprises Debt Securities [Member]    
Amortized Cost    
Available for Sale, Total debt securities 174,150 283
Fair Value    
Available for Sale, Total debt securities 164,502 269
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 0  
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value 0  
US Government Sponsored-Enterprise Insured Loans | Residential Mortgage-Backed Securities [Member]    
Amortized Cost    
Available for Sale, Total debt securities 146,337 134,142
Fair Value    
Available for Sale, Total debt securities 134,464 129,863
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 771,047 823,630
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value 598,700 696,462
US Government Sponsored-Enterprise Insured Loans | Commercial Mortgage-Backed Securities [Member]    
Amortized Cost    
Available for Sale, Total debt securities 369,363 17,959
Fair Value    
Available for Sale, Total debt securities 347,399 16,958
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 752,924 763,370
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value 609,904 650,366
Government National Mortgage Association (GNMA) [Member] | Residential Mortgage-Backed Securities [Member]    
Amortized Cost    
Available for Sale, Total debt securities 5,542,393 5,000,015
Fair Value    
Available for Sale, Total debt securities 5,352,106 5,039,829
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 36,181 39,123
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value 31,634 36,884
Government National Mortgage Association (GNMA) [Member] | Commercial Mortgage-Backed Securities [Member]    
Amortized Cost    
Available for Sale, Total debt securities 111,099 113,374
Fair Value    
Available for Sale, Total debt securities 102,863 109,556
Amortized Cost    
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss 39,316 44,552
Fair Value    
Debt Securities, Held-to-Maturity, Fair Value $ 33,974 $ 40,138