Fair Value of Financial Instruments Recurring basis (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments
Total held-to-maturity securities	$ 48,442	$ 46,094
Total available-for-sale securities	636,880	606,108
U.S. Treasury and government agencies
Investments
Total available-for-sale securities	1	20
U.S. government sponsored agencies
Investments
Total available-for-sale securities	5,950	319
States and political subdivisions
Investments
Total available-for-sale securities	64,743	50,962
Residential mortgage-backed securities
Investments
Total available-for-sale securities	527,291	510,097
Commercial mortgage-backed securities
Investments
Total available-for-sale securities	27,847	32,304
Bank-issued trust preferred securities
Investments
Total available-for-sale securities	5,645	7,829
Equity securities
Investments
Total available-for-sale securities	5,403	4,577
Fair Value | Fair Value
Investments
Total held-to-maturity securities	48,442	46,094
Fair Value | Recurring Basis
Investments
Total available-for-sale securities	636,880	606,108
Fair Value | U.S. Treasury and government agencies | Recurring Basis
Investments
Total available-for-sale securities	1	20
Fair Value | U.S. government sponsored agencies | Recurring Basis
Investments
Total available-for-sale securities	5,950	319
Fair Value | States and political subdivisions | Fair Value
Investments
Total held-to-maturity securities	4,282	3,929
Fair Value | States and political subdivisions | Recurring Basis
Investments
Total available-for-sale securities	64,743	50,962
Fair Value | Residential mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	36,740	34,530
Fair Value | Residential mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	527,291	510,097
Fair Value | Commercial mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	7,420	7,635
Fair Value | Commercial mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	27,847	32,304
Fair Value | Bank-issued trust preferred securities | Recurring Basis
Investments
Total available-for-sale securities	5,645	7,829
Fair Value | Equity securities | Recurring Basis
Investments
Total available-for-sale securities	5,403	4,577
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value
Investments
Total held-to-maturity securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring Basis
Investments
Total available-for-sale securities	5,204	4,443
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury and government agencies | Recurring Basis
Investments
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government sponsored agencies | Recurring Basis
Investments
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | States and political subdivisions | Fair Value
Investments
Total held-to-maturity securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | States and political subdivisions | Recurring Basis
Investments
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Bank-issued trust preferred securities | Recurring Basis
Investments
Total available-for-sale securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities | Recurring Basis
Investments
Total available-for-sale securities	5,204	4,443
Significant Other Observable Inputs (Level 2) | Fair Value
Investments
Total held-to-maturity securities	48,442	46,094
Significant Other Observable Inputs (Level 2) | Recurring Basis
Investments
Total available-for-sale securities	631,676	601,665
Significant Other Observable Inputs (Level 2) | U.S. Treasury and government agencies | Recurring Basis
Investments
Total available-for-sale securities	1	20
Significant Other Observable Inputs (Level 2) | U.S. government sponsored agencies | Recurring Basis
Investments
Total available-for-sale securities	5,950	319
Significant Other Observable Inputs (Level 2) | States and political subdivisions | Fair Value
Investments
Total held-to-maturity securities	4,282	3,929
Significant Other Observable Inputs (Level 2) | States and political subdivisions | Recurring Basis
Investments
Total available-for-sale securities	64,743	50,962
Significant Other Observable Inputs (Level 2) | Residential mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	36,740	34,530
Significant Other Observable Inputs (Level 2) | Residential mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	527,291	510,097
Significant Other Observable Inputs (Level 2) | Commercial mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	7,420	7,635
Significant Other Observable Inputs (Level 2) | Commercial mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	27,847	32,304
Significant Other Observable Inputs (Level 2) | Bank-issued trust preferred securities | Recurring Basis
Investments
Total available-for-sale securities	5,645	7,829
Significant Other Observable Inputs (Level 2) | Equity securities | Recurring Basis
Investments
Total available-for-sale securities	199	134
Significant Unobservable Inputs (Level 3) | Fair Value
Investments
Total held-to-maturity securities	0	0
Significant Unobservable Inputs (Level 3) | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | U.S. Treasury and government agencies | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | U.S. government sponsored agencies | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | States and political subdivisions | Fair Value
Investments
Total held-to-maturity securities	0	0
Significant Unobservable Inputs (Level 3) | States and political subdivisions | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | Residential mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	0	0
Significant Unobservable Inputs (Level 3) | Residential mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | Commercial mortgage-backed securities | Fair Value
Investments
Total held-to-maturity securities	0	0
Significant Unobservable Inputs (Level 3) | Commercial mortgage-backed securities | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | Bank-issued trust preferred securities | Recurring Basis
Investments
Total available-for-sale securities	0	0
Significant Unobservable Inputs (Level 3) | Equity securities | Recurring Basis
Investments
Total available-for-sale securities	$ 0	$ 0