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Investment Securities - Additional Information (Details)
 6 Months Ended
Jun. 30, 2023
USD ($)
Security
Dec. 31, 2022
USD ($)
Securities
Security
Schedule Of Available For Sale Securities [Line Items]    
Equity securities, at fair value $ 409,000 $ 311,000
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 $ 904,000,000 770,000,000
Available-for-sale, 12 months or longer, Fair Value 1,092,621,000 677,083,000
12 months or longer, unrealized losses $ 211,927,000 $ 143,282,000
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 43 16
Available-for-sale, 12 months or longer, Fair Value $ 213,600,000 $ 163,520,000
12 months or longer, unrealized losses $ 31,540,000 $ 28,914,000
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions | Securities   0
Obligations of States and Political Subdivisions    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 225 36
Available-for-sale, 12 months or longer, Fair Value $ 230,437,000 $ 45,419,000
12 months or longer, unrealized losses $ 55,831,000 $ 16,624,000
Mortgage-backed Securities: GSE Residential    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 251 91
Available-for-sale, 12 months or longer, Fair Value $ 590,760,000 $ 461,446,000
12 months or longer, unrealized losses $ 119,552,000 $ 96,900,000
Other Securities    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 42 5
Available-for-sale, 12 months or longer, Fair Value $ 57,824,000 $ 6,698,000
12 months or longer, unrealized losses $ 5,004,000 $ 844,000