Fair Value of Financial Instruments (Assets Measured at Fair Value Recurring) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Recurring Basis
Available-for-sale securities	$ 797,021	$ 777,940
Held-to-maturity securities	42,808	43,227
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	42,808	43,227
Significant Unobservable Inputs (Level 3)
Recurring Basis
Held-to-maturity securities	0	0
U.S. government sponsored agencies
Recurring Basis
Available-for-sale securities		1,000
States and political subdivisions
Recurring Basis
Available-for-sale securities	104,560	117,230
Held-to-maturity securities	4,463	4,041
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	4,463	4,041
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	672,106	626,567
Held-to-maturity securities	33,690	33,762
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	33,690	33,762
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	7,128	19,291
Held-to-maturity securities	4,655	5,424
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	4,655	5,424
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	5,154	4,899
Equity securities
Recurring Basis
Available-for-sale securities	8,073	8,953
Recurring Basis [Member]
Recurring Basis
Available-for-sale securities	797,021	777,940
Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	7,914	8,734
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	789,107	769,206
Recurring Basis [Member] | 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		1,000
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
Recurring Basis [Member] | U.S. government sponsored agencies | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities		1,000
Recurring Basis [Member] | U.S. government sponsored agencies | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities		0
Recurring Basis [Member] | States and political subdivisions
Recurring Basis
Available-for-sale securities	104,560	117,230
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	104,560	117,230
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	672,106	626,567
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	672,106	626,567
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	7,128	19,291
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	7,128	19,291
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	5,154	4,899
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	5,154	4,899
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	8,073	8,953
Recurring Basis [Member] | Equity securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Recurring Basis
Available-for-sale securities	7,914	8,734
Recurring Basis [Member] | Equity securities | Significant Other Observable Inputs (Level 2)
Recurring Basis
Available-for-sale securities	159	219
Recurring Basis [Member] | Equity securities | Significant Unobservable Inputs (Level 3)
Recurring Basis
Available-for-sale securities	$ 0	$ 0