CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income:
Loans, including fees	$ 184,648,800	$ 169,252,739	$ 160,036,709
Securities:
Taxable	14,227,172	14,504,464	16,931,417
Tax-exempt	6,167,264	6,378,345	6,576,701
Federal funds sold and other	1,126,726	1,146,867	1,876,731
Total interest income	206,169,962	191,282,415	185,421,558
Interest expense:
Deposits	9,953,930	11,721,387	16,842,852
Securities sold under agreements to repurchase	140,623	238,775	455,499
Federal Home Loan Bank advances and other borrowings	3,090,860	3,423,617	5,258,749
Total interest expense	13,185,413	15,383,779	22,557,100
Net interest income	192,984,549	175,898,636	162,864,458
Provision for loan losses	3,634,660	7,856,522	5,568,830
Net interest income after provision for loan losses	189,349,889	168,042,114	157,295,628
Noninterest income:
Service charges on deposit accounts	11,707,274	10,557,528	9,917,754
Investment services	9,382,670	8,038,425	6,984,970
Insurance sales commissions	4,612,583	4,537,150	4,461,404
Trust fees	4,601,036	3,747,241	3,195,950
Gains on mortgage loans sold, net	5,630,371	6,243,411	6,698,618
Gain on sale of investment securities, net	29,221	(1,466,475)	2,150,605
Other noninterest income	16,639,323	15,446,298	9,987,335
Total noninterest income	52,602,478	47,103,578	43,396,636
Noninterest expense:
Salaries and employee benefits	88,319,567	82,646,967	78,056,564
Equipment and occupancy	24,087,335	21,273,454	20,420,333
Other real estate expense	664,289	3,113,046	11,544,067
Marketing and other business development	4,127,949	3,638,941	3,635,810
Postage and supplies	2,391,838	2,249,950	2,379,730
Amortization of intangibles	947,678	1,262,524	2,738,994
Other noninterest expense	15,761,027	15,076,332	19,389,368
Total noninterest expense	136,299,683	129,261,214	138,164,866
Income (loss) before income taxes	105,652,684	85,884,478	62,527,398
Income tax expense (benefit)	35,181,517	28,158,277.000	20,643,517
Net income (loss)	70,471,167	57,726,201	41,883,881
Preferred stock dividends	0	0	1,660,868
Accretion on preferred stock discount	0	0	2,153,172
Net income (loss) available to common stockholders	$ 70,471,167	$ 57,726,201	$ 38,069,841
Per share information:
Basic net income (loss) per common share available to common stockholders (in dollars per share)	$ 2.03	$ 1.69	$ 1.12
Diluted net income (loss) per common share available to common stockholders (in dollars per share)	$ 2.01	$ 1.67	$ 1.10
Weighted average common shares outstanding:
Basic (in shares)	34,723,335	34,200,770	33,899,667
Diluted (in shares)	35,126,890	34,509,261	34,487,808