Fair Value Measurements, Assets and Liabilities Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	$ 371,839	$ 355,303
U.S. Treasury [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	148,740	128,585
State and political subdivisions [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	210,273	211,489
Readily Available Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	0
Total	417,033	370,550
Observable Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	(3,447)	(2,349)
Total	259,756	258,625
Company Determined Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	0
Total	2,611,521	2,603,233
Recurring Basis [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	368,392	352,954
Recurring Basis [Member] | U.S. Treasury [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	148,740	128,585
Recurring Basis [Member] | State and political subdivisions [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	210,273	211,489
Recurring Basis [Member] | Other securities (FHLB, FHLMC and FNMA) [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	12,826	15,229
Recurring Basis [Member] | Interest rate swaps [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	(3,447)	(2,349)
Recurring Basis [Member] | Readily Available Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	148,740	128,585
Recurring Basis [Member] | Readily Available Market Prices [Member] | U.S. Treasury [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	148,740	128,585
Recurring Basis [Member] | Readily Available Market Prices [Member] | State and political subdivisions [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	0	0
Recurring Basis [Member] | Readily Available Market Prices [Member] | Other securities (FHLB, FHLMC and FNMA) [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	0	0
Recurring Basis [Member] | Readily Available Market Prices [Member] | Interest rate swaps [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	0
Recurring Basis [Member] | Observable Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	219,652	224,369
Recurring Basis [Member] | Observable Market Prices [Member] | U.S. Treasury [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	0	0
Recurring Basis [Member] | Observable Market Prices [Member] | State and political subdivisions [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	210,273	211,489
Recurring Basis [Member] | Observable Market Prices [Member] | Other securities (FHLB, FHLMC and FNMA) [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	12,826	15,229
Recurring Basis [Member] | Observable Market Prices [Member] | Interest rate swaps [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	(3,447)	(2,349)
Recurring Basis [Member] | Company Determined Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	0	0
Recurring Basis [Member] | Company Determined Market Prices [Member] | U.S. Treasury [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	0	0
Recurring Basis [Member] | Company Determined Market Prices [Member] | State and political subdivisions [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	0	0
Recurring Basis [Member] | Company Determined Market Prices [Member] | Other securities (FHLB, FHLMC and FNMA) [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	0	$ 0
Recurring Basis [Member] | Company Determined Market Prices [Member] | Interest rate swaps [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	$ 0