CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income	$ 127,224,695	$ 95,509,402	$ 70,471,167
Adjustments to reconcile net income to net cash provided by operating activities:
Net amortization/accretion of premium/discount on securities	8,630,048	5,231,583	4,526,497
Depreciation and amortization	16,995,490	10,268,576	9,282,197
Provision for loan losses	18,328,058	9,188,497	3,634,660
Investment gains on sales and impairments, net	(395,186)	(552,063)	(29,221)
Gain on mortgage loans sold, net	(15,754,473)	(7,668,960)	(5,630,371)
Stock-based compensation expense	10,970,849	7,341,603	5,308,167
Deferred tax expense	14,390,035	5,819,463	394,452
Losses (gains) on disposition of other real estate and other investments	140,992	(433,911)	(74,807)
Gains from equity method investment	(31,402,923)	(20,591,484)	0
Excess tax benefit from stock compensation	(4,604,007)	(4,116,120)	(1,698,521)
Gain on other loans sold, net	(885,320)	0	0
Other loans held for sale:
Loans originated	(112,669,589)	0	0
Loans sold	90,966,938	0	0
Mortgage loans held for sale:
Loans originated	(784,213,817)	(524,679,767)	(331,135,205)
Loans sold	803,498,453	519,134,000	335,577,000
Decrease (increase) in other assets	(17,411,223)	(2,359,490)	4,014,267
Decrease (increase) in other liabilities	2,829,656	(7,487,499)	417,873
Net cash provided by operating activities	126,638,676	84,603,830	95,058,155
Activities in securities available-for-sale:
Purchases	(583,330,035)	(342,192,699)	(149,051,923)
Sales	72,829,440	189,029,458	2,360,478
Maturities, prepayments and calls	280,805,769	146,441,236	123,949,792
Activities in securities held-to-maturity:
Purchases	(560,000)	(1,550,995)	(923,652)
Sales	0	0	0
Maturities, prepayments and calls	6,200,000	8,185,000	1,229,874
Increase in loans, net	(966,207,993)	(668,297,036)	(455,357,214)
Purchases of premises and equipment and software	(17,058,292)	(10,870,851)	(5,878,562)
Proceeds from sales of software, premises and equipment	2,187,381	782,482	0
Proceeds from sale of mortgage servicing rights	6,747,626	0	0
Acquisitions, net of cash acquired	17,608,471	5,876,592	0
Increase in equity method investment	(74,100,000)	(75,440,530)	0
Dividends received from equity method investment	28,982,009	7,152,000	0
Increase in other investments	(27,508,882)	(1,712,685)	(4,208,447)
Net cash used in investing activities	(1,253,404,506)	(742,598,028)	(487,879,654)
Financing activities:
Net increase in deposits	822,306,826	783,352,902	249,132,187
Net increase (decrease) in repurchase agreements	6,622,260	(32,784,245)	23,529,404
Advances from Federal Home Loan Bank:
Issuances	1,934,000,000	1,135,000,000	790,000,000
Payments	(1,934,093,153)	(1,092,781,984)	(685,093,244)
Proceeds from subordinated debt and other borrowings, net of issuance costs	243,226,783	59,129,504	0
Repayment of other borrowings	(74,000,302)	(50,290,006)	(2,500,000)
Principal payments of capital lease obligation	(70,401)	0	0
Exercise of common stock options and stock appreciation rights, net of shares surrendered for taxes	11,589,495	3,602,805	6,421,689
Excess tax benefit from stock compensation	4,604,007	4,116,120	1,698,521
Common dividends paid	(24,725,598)	(18,307,075)	(11,398,285)
Net cash provided by financing activities	989,459,917	791,038,021	371,790,272
Net increase (decrease) in cash and cash equivalents	(137,305,913)	133,043,823	(21,031,227)
Cash and cash equivalents, beginning of year	320,951,333	187,907,510	208,938,737
Cash and cash equivalents, end of year	$ 183,645,420	$ 320,951,333	$ 187,907,510