Fair Value of Financial Instruments (Assets Measured at Fair Value Recurring) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Recurring Basis
Available-for-sale securities	$ 793,285	$ 636,880
Held-to-maturity securities	47,135	48,442
Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Held-to-maturity securities	0	0
Significant Other Observable Inputs (Level 2)
Recurring Basis
Held-to-maturity securities	47,135	48,442
Significant Unobservable Inputs (Level 3)
Recurring Basis
Held-to-maturity securities	0	0
U.S. Treasury and government agencies
Recurring Basis
Available-for-sale securities	0	1
U.S. government sponsored agencies
Recurring Basis
Available-for-sale securities	2,993	5,950
States and political subdivisions
Recurring Basis
Available-for-sale securities	115,249	64,743
Held-to-maturity securities	4,258	4,282
States and political subdivisions | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Held-to-maturity securities	0	0
States and political subdivisions | Significant Other Observable Inputs (Level 2)
Recurring Basis
Held-to-maturity securities	4,258	4,282
States and political subdivisions | Significant Unobservable Inputs (Level 3)
Recurring Basis
Held-to-maturity securities	0	0
Residential mortgage-backed securities
Recurring Basis
Available-for-sale securities	639,327	527,291
Held-to-maturity securities	36,080	36,740
Residential mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Held-to-maturity securities	0	0
Residential mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Held-to-maturity securities	36,080	36,740
Residential mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Held-to-maturity securities	0	0
Commercial mortgage-backed securities
Recurring Basis
Available-for-sale securities	24,348	27,847
Held-to-maturity securities	6,797	7,420
Commercial mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Held-to-maturity securities	0	0
Commercial mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Held-to-maturity securities	6,797	7,420
Commercial mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Held-to-maturity securities	0	0
Bank-issued trust preferred securities
Recurring Basis
Available-for-sale securities	4,776	5,645
Equity securities
Recurring Basis
Available-for-sale securities	6,592	5,403
Recurring Basis [Member]
Recurring Basis
Available-for-sale securities	793,285	636,880
Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	6,383	5,204
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	786,902	631,676
Recurring Basis [Member] | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | U.S. Treasury and government agencies
Recurring Basis
Available-for-sale securities	0	1
Recurring Basis [Member] | U.S. Treasury and government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | U.S. Treasury and government agencies | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	0	1
Recurring Basis [Member] | U.S. Treasury and government agencies | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | U.S. government sponsored agencies
Recurring Basis
Available-for-sale securities	2,993	5,950
Recurring Basis [Member] | U.S. government sponsored agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | U.S. government sponsored agencies | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	2,993	5,950
Recurring Basis [Member] | U.S. government sponsored agencies | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | States and political subdivisions
Recurring Basis
Available-for-sale securities	115,249	64,743
Recurring Basis [Member] | States and political subdivisions | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | States and political subdivisions | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	115,249	64,743
Recurring Basis [Member] | States and political subdivisions | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Residential mortgage-backed securities
Recurring Basis
Available-for-sale securities	639,327	527,291
Recurring Basis [Member] | Residential mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Residential mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	639,327	527,291
Recurring Basis [Member] | Residential mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Commercial mortgage-backed securities
Recurring Basis
Available-for-sale securities	24,348	27,847
Recurring Basis [Member] | Commercial mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Commercial mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	24,348	27,847
Recurring Basis [Member] | Commercial mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Bank-issued trust preferred securities
Recurring Basis
Available-for-sale securities	4,776	5,645
Recurring Basis [Member] | Bank-issued trust preferred securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Bank-issued trust preferred securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	4,776	5,645
Recurring Basis [Member] | Bank-issued trust preferred securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	0	0
Recurring Basis [Member] | Equity securities
Recurring Basis
Available-for-sale securities	6,592	5,403
Recurring Basis [Member] | Equity securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	6,383	5,204
Recurring Basis [Member] | Equity securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	209	199
Recurring Basis [Member] | Equity securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	$ 0	$ 0