Securities - Exposure to Bond Issuers that Exceeded 10% of Stockholders' Equity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Concentration Risk [Line Items]
Amortized Cost	$ 380,147	$ 238,548
Stockholders' Equity, Total
Concentration Risk [Line Items]
Amortized Cost	270,749
Fair Value	269,786
Stockholders' Equity, Total | Federal Home Loan Bank (FHLB)
Concentration Risk [Line Items]
Amortized Cost	33,327
Fair Value	33,306
Stockholders' Equity, Total | Federal Home Loan Mortgage Corporation (Freddie Mac-FHLMC)
Concentration Risk [Line Items]
Amortized Cost	95,209
Fair Value	94,507
Stockholders' Equity, Total | Federal Farm Credit Bank (FFCB)
Concentration Risk [Line Items]
Amortized Cost	142,213
Fair Value	$ 141,973