Securities (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Securities available-for-sale [Abstract]
Amortized Cost	$ 706,023,000	$ 700,492,000
Gross Unrealized Gains	19,514,000	16,306,000
Gross Unrealized Losses	10,616,000	23,342,000
Fair Value	714,920,906	693,456,314
Securities pledged as collateral to secure public funds and other deposits or securities sold under agreements to repurchase	598,900,000
Securities held-to-maturity [Abstract]
Amortized Cost	38,107,000	39,796,000
Gross Unrealized Gains	186,000	72,000
Gross Unrealized Losses	181,000	1,051,000
Fair Value	38,112,282	38,817,467
Available-for-sale, Amortized Cost [Abstract]
Due in one year or less	7,676,000
Due in one year to five years	38,854,000
Due in five years to ten years	152,474,000
Due after ten years	63,294,000
Mortgage-backed securities	429,834,000
Asset-backed securities	13,891,000
Amortized Cost	706,023,000
Available-for-sale, Fair Value [Abstract]
Due in one year or less	7,725,000
Due in one year to five years	40,900,000
Due in five years to ten years	154,797,000
Due after ten years	62,079,000
Mortgage-backed securities	435,654,000
Asset-backed securities	13,766,000
Fair Value	714,920,906
Held-to-maturity, Amortized Cost [Abstract]
Due in one year or less	1,770,000
Due in one year to five years	16,485,000
Due in five years to ten years	13,323,000
Due after ten years	6,529,000
Mortgage-backed securities	0
Asset-backed securities	0
Amortized Cost	38,106,986	39,795,649
Held-to-maturity, Fair Value [Abstract]
Due in one year or less	1,776,000
Due in one year to five years	16,562,000
Due in five years to ten years	13,263,000
Due after ten years	6,511,000
Mortgage-backed securities	0
Asset-backed securities	0
Fair Value	38,112,282	38,817,467
State and Municipal Securities [Member]
Securities held-to-maturity [Abstract]
Amortized Cost	38,107,000	39,796,000
Gross Unrealized Gains	186,000	72,000
Gross Unrealized Losses	181,000	1,051,000
Fair Value	38,112,282	38,817,467
Held-to-maturity, Fair Value [Abstract]
Fair Value	38,112,282	38,817,467
US Treasury Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	0
U.S. Government Agency Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	117,053,000	117,282,000
Gross Unrealized Gains	14,000	13,000
Gross Unrealized Losses	5,969,000	13,422,000
Fair Value	111,098,000	103,873,000
Mortgage-backed Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	429,834,000	411,967,000
Gross Unrealized Gains	10,086,000	9,771,000
Gross Unrealized Losses	4,266,000	8,802,000
Fair Value	435,654,000	412,936,000
State and Municipal Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	135,043,000	143,763,000
Gross Unrealized Gains	8,407,000	5,504,000
Gross Unrealized Losses	255,000	856,000
Fair Value	143,195,000	148,411,000
Asset-backed Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	13,891,000	17,262,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	125,000	255,000
Fair Value	13,766,000	17,007,000
Corporate Notes and Other [Member]
Securities available-for-sale [Abstract]
Amortized Cost	10,202,000	10,218,000
Gross Unrealized Gains	1,007,000	1,018,000
Gross Unrealized Losses	1,000	7,000
Fair Value	$ 11,208,000	$ 11,229,000