CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income (loss)	$ 95,509,402	$ 70,471,167	$ 57,726,201
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization/accretion of premium/discount on securities	5,231,583	4,526,497	4,438,303
Depreciation and amortization	10,268,576	9,282,197	9,245,876
Provision for loan losses	9,188,497	3,634,660	7,856,522
Investment gains (losses) on sales and impairments, net	(552,063)	(29,221)	1,466,475
Gain on mortgage loans sold, net	(7,668,960)	(5,630,371)	(6,243,411)
Stock-based compensation expense	7,341,603	5,308,167	4,082,132
Deferred tax expense (benefit)	5,819,463	394,452	1,841,044
Losses on disposition of other real estate and other investments	(433,911)	(74,807)	3,103,008
Gains from equity method investment	(20,591,484)	0	0
Excess tax benefit from stock compensation	(4,116,120)	(1,698,521)	(389,415)
Mortgage loans held for sale:
Loans originated	(524,679,767)	(331,135,205)	(385,173,288)
Loans sold	519,134,000	335,577,000	419,761,000
Decrease in other assets	(3,229,986)	4,014,267	11,567,952
(Decrease) increase in other liabilities	(7,487,499)	417,873	(2,847,047)
Net cash provided by operating activities	83,733,334	95,058,155	126,435,352
Activities in available-for-sale securities:
Purchases	(342,192,699)	(149,051,923)	(233,887,505)
Sales	189,029,458	2,360,478	23,439,144
Maturities, prepayments and calls	146,441,236	123,949,792	143,322,733
Activities in held-to-maturity securities:
Purchases	(1,550,995)	(923,652)	(3,496,186)
Sales	0	0	0
Maturities, prepayments and calls	8,185,000	1,229,874	3,623,800
Increase in loans, net	(668,297,036)	(455,357,214)	(447,907,395)
Purchases of premises and equipment and software	(10,870,851)	(5,878,562)	(5,293,919)
Proceeds from sales of software, premises and equipment	782,482	0	0
Purchase of bank owned life insurance	0	0	(38,352,344)
Acquisitions of CapitalMark and Magna, net of cash acquired	5,876,592	0	0
Increase in equity-method investment, net of dividends received	(68,288,530)	0	0
Increase in other investments	(1,712,685)	(4,208,447)	(6,141,232)
Net cash used in investing activities	(742,598,028)	(487,879,654)	(564,692,904)
Financing activities:
Net increase in deposits	783,352,902	249,132,187	518,284,740
Net (decrease) increase in repurchase agreements	(32,784,245)	23,529,404	(44,202,149)
Advances from Federal Home Loan Bank:
Issuances	1,135,000,000	790,000,000	600,000,000
Payments	(1,092,781,984)	(685,093,244)	(585,144,603)
Net (decrease) increase in subordinated debt and other borrowings	9,709,994	(2,500,000)	(7,500,000)
Exercise of common stock options, stock appreciation rights and restricted shares, net of shares surrendered for taxes	3,602,805	6,421,689	2,894,908
Excess tax benefit from stock compensation	4,116,120	1,698,521	389,415
Common stock dividends paid	(18,307,075)	(11,398,285)	(2,814,691)
Net cash provided by financing activities	791,908,517	371,790,272	481,907,620
Net increase (decrease) in cash and cash equivalents	133,043,823	(21,031,227)	43,650,068
Cash and cash equivalents, beginning of year	187,907,510	208,938,737	165,288,669
Cash and cash equivalents, end of year	$ 320,951,333	$ 187,907,510	$ 208,938,737