Income Taxes (Reconciliation of Expected Income Tax Benefit Computed Using Federal Statutory Income Tax Rate) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Tax Disclosure [Abstract]                      
Computed tax expense                 $ 12,604 $ 12,220 $ 12,008
Tax exempt income                 (704) (510) (623)
Income from life insurance                 (503) (459) (484)
State taxes, net of federal benefit                 328 260 297
Low income housing credits                 (286) (299) (328)
Goodwill impairment                 0 991 0
Other                 1 (71) 12
Income tax expense $ 2,523 $ 3,154 $ 3,001 $ 2,762 $ 3,560 $ 2,952 $ 2,952 $ 2,668 $ 11,440 $ 12,132 $ 10,882
Income tax rate used for calculations                 35.00% 35.00%