Fair Value of Assets and Liabilities - Balances of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Assets:
Available-for-Sale: Fair Value	$ 2,666,723	$ 2,844,823
Loans Held for Sale	3,359	1,035
Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	96,540	95,265
Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,637	48,628
Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	788,754	794,658
Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	675,204	732,828
Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	744,714	793,871
Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	1,558,711	1,672,366
Commercial - Government Agencies or Sponsored Agencies
Assets:
Available-for-Sale: Fair Value	138,793	145,667
Fair Value, Measurements, Recurring
Assets:
Available-for-Sale: Fair Value	2,666,723	2,844,823
Loans Held for Sale	3,359	1,035
Mortgage Servicing Rights	695	717
Other Assets	53,202	47,755
Derivatives	162,753	47,717
Total Assets Measured at Fair Value on a Recurring Basis	2,886,732	2,942,047
Liabilities:
Derivatives	$ 162,517	$ 168,037
Derivative Liability Statement Of Financial Position [ExtensibleEnumeration]	Other Liabilities	Other Liabilities
Total Liabilities Measured at Fair Value on a Recurring Basis	$ 162,517	$ 168,037
Fair Value, Measurements, Recurring | Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	221,081	233,906
Fair Value, Measurements, Recurring | Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	96,540	95,265
Fair Value, Measurements, Recurring | Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,637	48,628
Fair Value, Measurements, Recurring | Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	788,754	794,658
Fair Value, Measurements, Recurring | Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	675,204	732,828
Fair Value, Measurements, Recurring | Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	744,714	793,871
Fair Value, Measurements, Recurring | Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	138,793
Fair Value, Measurements, Recurring | Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	1,558,711	1,672,366
Fair Value, Measurements, Recurring | Commercial - Government Agencies or Sponsored Agencies
Assets:
Available-for-Sale: Fair Value		145,667
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Assets:
Available-for-Sale: Fair Value	142,478	141,944
Loans Held for Sale	0	0
Mortgage Servicing Rights	0	0
Other Assets	53,202	47,755
Derivatives	0	0
Total Assets Measured at Fair Value on a Recurring Basis	195,680	189,699
Liabilities:
Derivatives	$ 0	$ 0
Derivative Liability Statement Of Financial Position [ExtensibleEnumeration]	Other Liabilities	Other Liabilities
Total Liabilities Measured at Fair Value on a Recurring Basis	$ 0	$ 0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	142,478	141,944
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Commercial - Government Agencies or Sponsored Agencies
Assets:
Available-for-Sale: Fair Value		0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Available-for-Sale: Fair Value	2,524,245	2,702,879
Loans Held for Sale	3,359	1,035
Mortgage Servicing Rights	0	0
Other Assets	0	0
Derivatives	34	1,822
Total Assets Measured at Fair Value on a Recurring Basis	2,527,638	2,705,736
Liabilities:
Derivatives	$ 0	$ 70
Derivative Liability Statement Of Financial Position [ExtensibleEnumeration]	Other Liabilities	Other Liabilities
Total Liabilities Measured at Fair Value on a Recurring Basis	$ 0	$ 70
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	78,603	91,962
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	96,540	95,265
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	1,637	48,628
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	788,754	794,658
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	675,204	732,828
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	744,714	793,871
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	138,793
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	1,558,711	1,672,366
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3)
Assets:
Available-for-Sale: Fair Value	0	0
Loans Held for Sale	0	0
Mortgage Servicing Rights	695	717
Other Assets	0	0
Derivatives	162,719	45,895
Total Assets Measured at Fair Value on a Recurring Basis	163,414	46,612
Liabilities:
Derivatives	$ 162,517	$ 167,967
Derivative Liability Statement Of Financial Position [ExtensibleEnumeration]	Other Liabilities	Other Liabilities
Total Liabilities Measured at Fair Value on a Recurring Basis	$ 162,517	$ 167,967
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Debt Securities Issued by the U.S. Treasury and Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Debt Securities Issued by States and Political Subdivisions
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Debt Securities Issued by Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Debt Securities Issued by Corporations
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Residential - Government Agencies
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Residential - U.S. Government-Sponsored Enterprises
Assets:
Available-for-Sale: Fair Value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Commercial - Government Agencies
Assets:
Available-for-Sale: Fair Value	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Mortgage-Backed Securities
Assets:
Available-for-Sale: Fair Value	$ 0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 3) | Commercial - Government Agencies or Sponsored Agencies
Assets:
Available-for-Sale: Fair Value		$ 0