Fair Market Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	$ 1,357,597	$ 997,261		$ 1,357,597		$ 997,261
Equity securities at fair value	2,523	2,471		2,523		2,471
Assets measured-nonrecurring basis [Abstract]
Collateral dependent loans	1,279	1,768		1,279		1,768
Reconciliation of beginning and ending balances of recurring fair value measurements recognized in balance sheet using significant unobservable (Level 3) inputs [Roll Forward]
Total gains (losses)	(79)		$ (6)	$ 473	$ (1,165)
Minimum [Member]
Other real estate owned [Abstract]
Typical frequency of periodic reviews				12 months
Maximum [Member]
Other real estate owned [Abstract]
Typical frequency of periodic reviews				18 months
Frequency of periodic reviews in general				24 months
U.S. Treasury and Government Agencies [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	245,695	148,793		$ 245,695		148,793
State and Political Subdivisions [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	261,577	140,416		261,577		140,416
U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	757,750	651,807		757,750		651,807
Other Debt Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	92,575	56,245		92,575		56,245
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	181,160	74,991		181,160		74,991
Equity securities at fair value	0	0		0		0
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	1,176,437	922,270		1,176,437		922,270
Equity securities at fair value	0	0		0		0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Equity securities at fair value	2,523	2,471		2,523		2,471
Recurring [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Equity securities at fair value	2,523	2,471		2,523		2,471
Mortgage servicing rights	5,899	4,068		5,899		4,068
Recurring [Member] | U.S. Treasury and Government Agencies [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	245,695	148,793		245,695		148,793
Recurring [Member] | State and Political Subdivisions [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	261,577	140,416		261,577		140,416
Recurring [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	757,750	651,807		757,750		651,807
Recurring [Member] | Other Debt Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	92,575	56,245		92,575		56,245
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Equity securities at fair value	0	0		0		0
Mortgage servicing rights	0	0		0		0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and Government Agencies [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	181,160	74,991		181,160		74,991
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | State and Political Subdivisions [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Debt Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Equity securities at fair value	0	0		0		0
Mortgage servicing rights	0	0		0		0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and Government Agencies [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	64,535	73,802		64,535		73,802
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | State and Political Subdivisions [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	261,577	140,416		261,577		140,416
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	757,750	651,807		757,750		651,807
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Debt Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	92,575	56,245		92,575		56,245
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Equity securities at fair value	2,523	2,471		2,523		2,471
Mortgage servicing rights	5,899	4,068		5,899		4,068
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and Government Agencies [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | State and Political Subdivisions [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Government Sponsored Agency Mortgage-backed Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Debt Securities [Member]
Assets Measured at Fair Value on Recurring Basis [Abstract]
Debt securities available-for-sale	0	0		0		0
Recurring [Member] | Equity Securities [Member]
Reconciliation of beginning and ending balances of recurring fair value measurements recognized in balance sheet using significant unobservable (Level 3) inputs [Roll Forward]
Beginning balance	2,243		1,721	2,471	1,953	1,953
Total unrealized gains (losses) included in net income	280		373	52	141
Issues	0		0	0	0
Settlements	0		0	0	0
Ending balance	2,523	2,471	2,094	2,523	2,094	2,471
Total gains (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	280		373	52	141
Recurring [Member] | Mortgage Servicing Rights [Member]
Reconciliation of beginning and ending balances of recurring fair value measurements recognized in balance sheet using significant unobservable (Level 3) inputs [Roll Forward]
Beginning balance	5,584		2,481	4,068	3,263	3,263
Total unrealized gains (losses) included in net income	(129)		(148)	901	(966)
Issues	674		415	1,410	560
Settlements	(230)		(230)	(480)	(339)
Ending balance	5,899	4,068	2,518	5,899	2,518	4,068
Total gains (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	(129)		(148)	901	(966)
Nonrecurring [Member]
Impaired loan (collateral dependent) [Abstract]
Fair value adjustments on collateral dependent loans	500	0	900	800	1,400	500
Other real estate owned [Abstract]
Other real estate owned, fair value adjustment	300	100	$ 200	400	$ 700	700
Nonrecurring [Member] | Fair Value [Member]
Assets measured-nonrecurring basis [Abstract]
Collateral dependent loans	1,279	1,768		1,279		1,768
Other real estate owned	1,424	2,395		1,424		2,395
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value [Member]
Assets measured-nonrecurring basis [Abstract]
Collateral dependent loans	0	0		0		0
Other real estate owned	0	0		0		0
Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member]
Assets measured-nonrecurring basis [Abstract]
Collateral dependent loans	0	0		0		0
Other real estate owned	0	0		0		0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value [Member]
Assets measured-nonrecurring basis [Abstract]
Collateral dependent loans	1,279	1,768		1,279		1,768
Other real estate owned	$ 1,424	$ 2,395		$ 1,424		$ 2,395