CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 173,979,487	$ 127,224,695	$ 95,509,402
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization/accretion of premium/discount on securities	12,846,572	8,630,048	5,231,583
Depreciation, amortization and accretion	(23,618,474)	16,995,490	10,268,576
Provision for loan losses	23,663,944	18,328,058	9,188,497
Gains on mortgage loans sold, net	(18,624,621)	(15,754,473)	(7,668,960)
Gain (Loss) on Sale of Investments	8,264,639	(395,186)	(552,063)
Stock-based compensation expense	19,538,083	10,970,849	7,341,603
Deferred tax expense excluding expense associated with revaluation of deferred tax assets/liabilities	28,164,871	14,390,035	5,819,463
Deferred tax asset/liability revaluation	31,485,672	0	0
Losses (gains) on disposition of other real estate and other investments	(202,980)	140,992	(433,911)
Income from equity method investment	(37,957,692)	(31,402,923)	(20,591,484)
Excess tax benefit from stock compensation	(5,365,493)	(4,604,007)	(4,116,120)
Gains on other loans sold, net	(1,488,140)	(885,320)	0
Other loans held for sale:
Other loans held for sale originated	(177,433,682)	(112,669,589)	0
Other loans held for sale sold	176,062,619	90,966,938	0
Mortgage loans held for sale:
Mortgage loans held for sale originated	(1,100,866,370)	(784,213,817)	(524,679,767)
Mortgage loans held for sale sold	1,090,489,558	803,498,453	519,134,000
Increase in other assets	(33,297,361)	(17,411,223)	(2,359,490)
(Decrease) increase in other liabilities	(17,699,526)	2,829,656	(7,487,499)
Net cash provided by operating activities	147,941,106	126,638,676	84,603,830
Activities in securities available-for-sale:
Purchases	(1,290,716,532)	(583,330,035)	(342,192,699)
Sales	363,898,141	72,829,440	189,029,458
Maturities, prepayments and calls	323,235,144	280,805,769	146,441,236
Activities in securities held-to-maturity:
Purchases	0	(560,000)	(1,550,995)
Maturities, prepayments and calls	4,115,000	6,200,000	8,185,000
Increase in loans, net	(1,558,646,425)	(966,207,993)	(668,297,036)
Purchases of premises and equipment and software	(53,498,776)	(17,058,292)	(10,870,851)
Payments to Acquire Life Insurance Policies	(55,000,000)	0	0
Proceeds from sales of software, premises, and equipment	23,038	2,187,381	782,482
Proceeds from sale of mortgage servicing rights	0	6,747,626	0
Acquisitions, net of cash acquired	155,141,674	17,608,471	5,876,592
Increase in equity method investment	0	(74,100,000)	(75,440,530)
Dividends received from equity method investment	21,650,046	28,982,009	7,152,000
Increase in other investments	(7,804,237)	(27,508,882)	(1,712,685)
Net cash used in investing activities	(2,097,602,927)	(1,253,404,506)	(742,598,028)
Financing activities:
Net increase in deposits	1,488,273,894	822,306,826	783,352,902
Net increase (decrease) in repurchase agreements	(12,754,500)	6,622,260	(32,784,245)
Advances from Federal Home Loan Bank:
Issuances	1,964,750,001	1,934,000,000	1,135,000,000
Payments	(1,051,066,604)	(1,934,093,153)	(1,092,781,984)
Proceeds from subordinated debt and other borrowings, net of issuance costs	0	243,226,783	59,129,504
Repayment of other borrowings	(220,100)	(74,000,302)	(50,290,006)
Principal payments of capital lease obligation	(148,641)	(70,401)	0
Proceeds from Issuance of Common Stock	192,193,750	0	0
Exercise of common stock options and stock appreciation rights, net of shares surrendered for taxes	493,347	11,589,495	3,602,805
Excess tax benefit from stock compensation	0	4,604,007	4,116,120
Common dividends paid	(35,907,449)	(24,725,598)	(18,307,075)
Net cash provided by financing activities	2,545,613,698	989,459,917	791,038,021
Net increase (decrease) in cash and cash equivalents	595,951,877	(137,305,913)	133,043,823
Cash and cash equivalents, beginning of year	183,645,420	320,951,333	187,907,510
Cash and cash equivalents, end of year	$ 779,597,297	$ 183,645,420	$ 320,951,333