Disclosures of Fair Values of Financial Instruments - Assets Measured at Fair Value on Recurring Basis (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Available-for-sale securities:
Total available-for-sale securities	$ 1,218,985,000	$ 1,421,422,000
Equity securities, at fair value	311,000	397,000
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale securities:
Total available-for-sale securities	220,527,000	203,815,000
Obligations of States and Political Subdivisions
Available-for-sale securities:
Total available-for-sale securities	287,698,000	395,457,000
Mortgage-backed Securities
Available-for-sale securities:
Total available-for-sale securities	627,880,000	791,038,000
Other Securities
Available-for-sale securities:
Total available-for-sale securities	82,880,000	31,112,000
Fair Value, Recurring
Available-for-sale securities:
Total available-for-sale securities	1,218,985,000	1,421,422,000
Equity securities, at fair value	311,000	397,000
Derivative assets: interest rate swaps	4,253,000	809,000
Assets, Fair Value Disclosure, Total	1,223,549,000	1,422,628,000
Derivative liabilities: interest swaps	3,100,000	1,476,000
Fair Value, Recurring | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale securities:
Total available-for-sale securities	220,527,000	203,815,000
Fair Value, Recurring | Obligations of States and Political Subdivisions
Available-for-sale securities:
Total available-for-sale securities	287,698,000	395,457,000
Fair Value, Recurring | Mortgage-backed Securities
Available-for-sale securities:
Total available-for-sale securities	627,880,000	791,038,000
Fair Value, Recurring | Other Securities
Available-for-sale securities:
Total available-for-sale securities	82,880,000	31,112,000
Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale securities:
Total available-for-sale securities	0	0
Equity securities, at fair value	311,000	397,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring
Available-for-sale securities:
Total available-for-sale securities	0	0
Equity securities, at fair value	311,000	397,000
Derivative assets: interest rate swaps	0	0
Assets, Fair Value Disclosure, Total	311,000	397,000
Derivative liabilities: interest swaps	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale securities:
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Obligations of States and Political Subdivisions
Available-for-sale securities:
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Mortgage-backed Securities
Available-for-sale securities:
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Recurring | Other Securities
Available-for-sale securities:
Total available-for-sale securities	0	0
Significant Other Observable Inputs (Level 2)
Available-for-sale securities:
Total available-for-sale securities	1,209,736,000	1,421,323,000
Equity securities, at fair value	0	0
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring
Available-for-sale securities:
Total available-for-sale securities	1,209,735,000	1,421,323,000
Equity securities, at fair value	0	0
Derivative assets: interest rate swaps	4,253,000	809,000
Assets, Fair Value Disclosure, Total	1,213,988,000	1,422,132,000
Derivative liabilities: interest swaps	3,100,000	1,476,000
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale securities:
Total available-for-sale securities	220,527,000	203,815,000
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Obligations of States and Political Subdivisions
Available-for-sale securities:
Total available-for-sale securities	287,698,000	395,358,000
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Mortgage-backed Securities
Available-for-sale securities:
Total available-for-sale securities	627,880,000	791,038,000
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring | Other Securities
Available-for-sale securities:
Total available-for-sale securities	73,630,000	31,112,000
Significant Unobservable Inputs (Level 3)
Available-for-sale securities:
Total available-for-sale securities	9,250,000	99,000
Equity securities, at fair value	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring
Available-for-sale securities:
Total available-for-sale securities	9,250,000	99,000
Equity securities, at fair value	0	0
Derivative assets: interest rate swaps	0	0
Assets, Fair Value Disclosure, Total	9,250,000	99,000
Derivative liabilities: interest swaps	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies
Available-for-sale securities:
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Obligations of States and Political Subdivisions
Available-for-sale securities:
Total available-for-sale securities	0	99,000
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Mortgage-backed Securities
Available-for-sale securities:
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring | Other Securities
Available-for-sale securities:
Total available-for-sale securities	$ 9,250,000	$ 0