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Investment Securities - Additional Information (Details)
 9 Months Ended
Sep. 30, 2022
USD ($)
Security
Dec. 31, 2021
USD ($)
Security
Schedule Of Available For Sale Securities [Line Items]    
Equity securities, at fair value $ 317,000 $ 397,000
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 $ 818,000,000 590,000,000
Available-for-sale, 12 months or longer, Fair Value 554,983,000 186,350,000
12 months or longer, unrealized losses $ 126,058,000 $ 4,627,000
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 16 6
Available-for-sale, 12 months or longer, Fair Value $ 132,392,000 $ 139,846,000
12 months or longer, unrealized losses $ 25,129,000 $ 2,936,000
Held-to-maturity, securities in unrealized loss positions, qualitative disclosure, number of positions | Security   0
Obligations of States and Political Subdivisions    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 36 0
Available-for-sale, 12 months or longer, Fair Value $ 37,212,000 $ 0
12 months or longer, unrealized losses $ 17,340,000 $ 0
Mortgage-backed Securities: GSE Residential    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 91 15
Available-for-sale, 12 months or longer, Fair Value $ 379,400,000 $ 46,504,000
12 months or longer, unrealized losses $ 83,018,000 $ 1,691,000
Other Securities    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 5 0
Available-for-sale, 12 months or longer, Fair Value $ 5,979,000 $ 0
12 months or longer, unrealized losses $ 571,000 $ 0