Securities (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Securities available-for-sale [Abstract]
Amortized Cost	$ 1,088,739,000	$ 930,708,000
Gross Unrealized Gains	23,449,000	13,642,000
Gross Unrealized Losses	2,967,000	9,285,000
Fair Value	1,109,221,784	935,064,745
Available-for-sale Securities	1,109,221,784	935,064,745
Securities pledged as collateral to secure public funds and other deposits or securities sold under agreements to repurchase	825,200,000
Securities held-to-maturity [Abstract]
Amortized Cost	28,512,000	31,377,000
Gross Unrealized Gains	581,000	257,000
Gross Unrealized Losses	0	48,000
Fair Value	29,092,450	31,585,303
Available-for-sale, Amortized Cost [Abstract]
Due in one year or less	3,295,000
Due in one year to five years	30,553,000
Due in five years to ten years	164,910,000
Due after ten years	62,863,000
Mortgage-backed securities	758,714,000
Asset-backed securities	68,404,000
Amortized Cost	1,088,739,000
Available-for-sale, Fair Value [Abstract]
Due in one year or less	3,311,000
Due in one year to five years	32,539,000
Due in five years to ten years	170,595,000
Due after ten years	63,482,000
Mortgage-backed securities	771,950,000
Asset-backed securities	67,344,000
Held-to-maturity, Amortized Cost [Abstract]
Due in one year or less	1,237,000
Due in one year to five years	9,522,000
Due in five years to ten years	11,296,000
Due after ten years	6,457,000
Mortgage-backed securities	0
Asset-backed securities	0
Amortized Cost	28,511,599	31,376,840
Held-to-maturity, Fair Value [Abstract]
Due in one year or less	1,239,000
Due in one year to five years	9,624,000
Due in five years to ten years	11,621,000
Due after ten years	6,609,000
Mortgage-backed securities	0
Asset-backed securities	0
Fair Value	29,092,450	31,585,303
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
Available-for-sale Securities	0	0
U.S. Government Agency Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	97,458,000	131,499,000
Gross Unrealized Gains	69,000	3,000
Gross Unrealized Losses	1,080,000	3,309,000
Fair Value	96,447,000	128,193,000
Available-for-sale Securities	96,447,000	128,193,000
Mortgage-backed Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	758,714,000	581,998,000
Gross Unrealized Gains	14,042,000	5,948,000
Gross Unrealized Losses	806,000	5,030,000
Fair Value	771,950,000	582,916,000
Available-for-sale Securities	771,950,000	582,916,000
State and Municipal Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	159,890,000	158,072,000
Gross Unrealized Gains	9,200,000	7,094,000
Gross Unrealized Losses	13,000	124,000
Fair Value	169,077,000	165,042,000
Available-for-sale Securities	169,077,000	165,042,000
Asset-backed Securities [Member]
Securities available-for-sale [Abstract]
Amortized Cost	68,404,000	49,598,000
Gross Unrealized Gains	2,000	8,000
Gross Unrealized Losses	1,062,000	805,000
Fair Value	67,344,000	48,801,000
Available-for-sale Securities	67,344,000	48,801,000
Corporate Notes and Other [Member]
Securities available-for-sale [Abstract]
Amortized Cost	4,273,000	9,541,000
Gross Unrealized Gains	136,000	589,000
Gross Unrealized Losses	6,000	17,000
Fair Value	4,403,000	10,113,000
Available-for-sale Securities	4,403,000	10,113,000
State and Municipal Securities [Member]
Securities held-to-maturity [Abstract]
Amortized Cost	28,512,000	31,377,000
Gross Unrealized Gains	581,000	257,000
Gross Unrealized Losses	0	48,000
Fair Value	29,092,450	31,585,303
Held-to-maturity, Fair Value [Abstract]
Fair Value	$ 29,092,450	$ 31,585,303