Investment Securities (Summary of Amortized Cost and Fair Value of Available-For-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	$ 686,128	$ 749,187	$ 614,744
Investment securities available-for-sale, Unrealized Gains	2,545	3,003	4,005
Investment securities available-for-sale, Unrealized Losses	2,967	3,326	2,774
Available-for-sale Securities, Total	685,706	748,864	615,975
US Treasury Securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	8,270	8,272
Investment securities available-for-sale, Unrealized Gains	24	0
Investment securities available-for-sale, Unrealized Losses	0	13
Available-for-sale Securities, Total	8,294	8,259
Government sponsored agencies [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	227,424	263,658	88,503
Investment securities available-for-sale, Unrealized Gains	683	356	346
Investment securities available-for-sale, Unrealized Losses	200	511	141
Available-for-sale Securities, Total	227,907	263,503	88,708
State and political subdivisions [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	26,476	45,157	40,165
Investment securities available-for-sale, Unrealized Gains	503	1,087	1,443
Investment securities available-for-sale, Unrealized Losses	14	17	0
Available-for-sale Securities, Total	26,965	46,227	41,608
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	213,621	240,465	265,673
Investment securities available-for-sale, Unrealized Gains	742	885	1,117
Investment securities available-for-sale, Unrealized Losses	1,694	1,543	1,422
Available-for-sale Securities, Total	212,669	239,807	265,368
Collateralized Mortgage Obligations [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	167,768	145,316	154,035
Investment securities available-for-sale, Unrealized Gains	245	261	376
Investment securities available-for-sale, Unrealized Losses	981	1,194	1,128
Available-for-sale Securities, Total	167,032	144,383	153,283
Corporate bonds [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	39,680	44,930	64,979
Investment securities available-for-sale, Unrealized Gains	76	213	456
Investment securities available-for-sale, Unrealized Losses	78	48	83
Available-for-sale Securities, Total	39,678	45,095	65,352
Preferred stock [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	2,889	1,389	1,389
Investment securities available-for-sale, Unrealized Gains	272	201	267
Investment securities available-for-sale, Unrealized Losses	0	0	0
Available-for-sale Securities, Total	$ 3,161	$ 1,590	$ 1,656