XML 49 R39.htm IDEA: XBRL DOCUMENT v3.23.3
Investment Securities - Additional Information (Details)
 9 Months Ended
Sep. 30, 2023
USD ($)
Security
Dec. 31, 2022
USD ($)
Securities
Security
Schedule Of Available For Sale Securities [Line Items]    
Equity securities, at fair value $ 3,932,000 $ 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 $ 860,000,000 770,000,000
Available-for-sale, 12 months or longer, Fair Value 1,039,657,000 677,083,000
12 months or longer, unrealized losses $ 250,785,000 $ 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 40 16
Available-for-sale, 12 months or longer, Fair Value $ 208,428,000 $ 163,520,000
12 months or longer, unrealized losses $ 33,681,000 $ 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 235 36
Available-for-sale, 12 months or longer, Fair Value $ 219,250,000 $ 45,419,000
12 months or longer, unrealized losses $ 72,090,000 $ 16,624,000
Mortgage-backed Securities: GSE Residential    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 278 91
Available-for-sale, 12 months or longer, Fair Value $ 555,338,000 $ 461,446,000
12 months or longer, unrealized losses $ 139,349,000 $ 96,900,000
Other Securities    
Schedule Of Available For Sale Securities [Line Items]    
Number of securities in unrealized loss positions | Security 43 5
Available-for-sale, 12 months or longer, Fair Value $ 56,641,000 $ 6,698,000
12 months or longer, unrealized losses $ 5,665,000 $ 844,000