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Investment Securities - Additional Information (Details)
$ in Thousands
 9 Months Ended
Sep. 30, 2024
USD ($)
Position
Security
Dec. 31, 2023
USD ($)
Position
Security
Schedule Of Available For Sale Securities [Line Items]    
Equity securities, at fair value $ 4,424 $ 4,074
Tax rate used to calculate tax-equivalent yields (in hundredths) 21.00%  
Percentage investment book value exceeds stockholders' equity (in hundredths) 10.00%  
Debt securities, available-for-sale, restricted $ 834,100 831,000
Available-for-sale, 12 months or longer, Fair Value 1,050,204 1,075,835
12 months or longer, unrealized losses $ 160,096 $ 192,616
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 28 36
Available-for-sale, 12 months or longer, Fair Value $ 193,524 $ 210,069
12 months or longer, unrealized losses $ 18,091 $ 26,215
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions | Position 0 0
Obligations of States and Political Subdivisions    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 247 237
Available-for-sale, 12 months or longer, Fair Value $ 251,107 $ 241,630
12 months or longer, unrealized losses $ 45,729 $ 49,038
Mortgage-backed Securities: GSE Residential    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 242 263
Available-for-sale, 12 months or longer, Fair Value $ 547,233 $ 566,197
12 months or longer, unrealized losses $ 93,269 $ 113,007
Other Securities    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 40 43
Available-for-sale, 12 months or longer, Fair Value $ 58,340 $ 57,939
12 months or longer, unrealized losses $ 3,007 $ 4,356