Securities (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Securities available-for-sale [Abstract]
Amortized Cost	$ 960,405,000	$ 718,685,000
Gross Unrealized Gains	17,015,000	19,530,000
Gross Unrealized Losses	5,125,000	6,161,000
Fair Value	972,295,754	732,054,785
Available-for-sale Securities	972,295,754	732,054,785
Securities pledged as collateral to secure public funds and other deposits or securities sold under agreements to repurchase	757,200,000
Available-for-sale Securities, Sold at a gain	125,000,000
Securities held-to-maturity [Abstract]
Amortized Cost	31,698,000	38,676,000
Gross Unrealized Gains	227,000	205,000
Gross Unrealized Losses	75,000	92,000
Fair Value	31,850,119	38,788,870
Available-for-sale, Amortized Cost [Abstract]
Due in one year or less	17,623,000
Due in one year to five years	38,088,000
Due in five years to ten years	180,128,000
Due after ten years	89,152,000
Mortgage-backed securities	584,066,000
Asset-backed securities	51,348,000
Amortized Cost	960,405,000
Available-for-sale, Fair Value [Abstract]
Due in one year or less	17,670,000
Due in one year to five years	39,631,000
Due in five years to ten years	184,465,000
Due after ten years	88,667,000
Mortgage-backed securities	590,971,000
Asset-backed securities	50,891,000
Held-to-maturity, Amortized Cost [Abstract]
Due in one year or less	962,000
Due in one year to five years	8,990,000
Due in five years to ten years	12,863,000
Due after ten years	8,883,000
Mortgage-backed securities	0
Asset-backed securities	0
Amortized Cost	31,698,000	38,675,527
Held-to-maturity, Fair Value [Abstract]
Due in one year or less	963,000
Due in one year to five years	9,058,000
Due in five years to ten years	12,964,000
Due after ten years	8,865,000
Mortgage-backed securities	0
Asset-backed securities	0
Fair Value	31,850,119	38,788,870
US Treasury Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	9,996,000	0
Gross Unrealized Gains	3,000	0
Gross Unrealized Losses	0	0
Fair Value	9,999,000	0
Available-for-sale Securities	9,999,000	0
U.S. Government Agency Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	147,268,000	117,098,000
Gross Unrealized Gains	83,000	12,000
Gross Unrealized Losses	2,548,000	3,654,000
Fair Value	144,803,000	113,456,000
Available-for-sale Securities	144,803,000	113,456,000
Mortgage-backed Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	584,066,000	447,757,000
Gross Unrealized Gains	8,797,000	10,322,000
Gross Unrealized Losses	1,892,000	2,240,000
Fair Value	590,971,000	455,839,000
Available-for-sale Securities	590,971,000	455,839,000
State and Municipal Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	156,469,000	130,545,000
Gross Unrealized Gains	7,200,000	8,213,000
Gross Unrealized Losses	175,000	180,000
Fair Value	163,494,000	138,578,000
Available-for-sale Securities	163,494,000	138,578,000
Asset-backed Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	51,348,000	13,089,000
Gross Unrealized Gains	52,000	14,000
Gross Unrealized Losses	509,000	85,000
Fair Value	50,891,000	13,018,000
Available-for-sale Securities	50,891,000	13,018,000
Corporate Notes and Other [Member]
Securities available-for-sale [Abstract]
Amortized Cost	11,258,000	10,196,000
Gross Unrealized Gains	880,000	969,000
Gross Unrealized Losses	1,000	2,000
Fair Value	12,137,000	11,163,000
Available-for-sale Securities	12,137,000	11,163,000
State and Municipal Securities [Member]
Securities held-to-maturity [Abstract]
Amortized Cost	31,698,000	38,676,000
Gross Unrealized Gains	227,000	205,000
Gross Unrealized Losses	75,000	92,000
Fair Value	31,850,119	38,788,870
Held-to-maturity, Fair Value [Abstract]
Fair Value	$ 31,850,119	$ 38,788,870