Fair Value Measurements, Assets and Liabilities Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	$ 254,984	$ 267,537
U.S. Treasury [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	39,894	27,482
State and political subdivisions [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Securities available for sale	166,331	178,395
Readily Available Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	0
Total	36,792	38,197
Observable Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	(3,464)	(3,938)
Total	289,311	298,877
Company Determined Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	0
Total	2,387,186	2,251,094
Recurring Basis [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	251,520	263,599
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	39,894	27,482
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	166,331	178,395
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	48,759	61,660
Recurring Basis [Member] | Interest rate swaps [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Derivative Financial Instruments	(3,464)	(3,938)
Recurring Basis [Member] | Readily Available Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	0	0
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	0	0
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] | Observable Market Prices [Member]
Summary of assets and liabilities measured at fair value on a recurring basis [Abstract]
Total	251,520	263,599
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	39,894	27,482
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	166,331	178,395
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	48,759	61,660
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	(3,464)	(3,938)
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