Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 0	$ (96,000)	$ 140,000
Current tax expense (benefit) [Abstract]
Federal	49,769,000	41,721,000	34,068,000
State	0	48,000	719,000
Total current tax expense (benefit)	49,769,000	41,769,000	34,787,000
Deferred tax expense (benefit) [Abstract]
Federal	12,776,000	4,963,000	(1,260,000)
State	1,614,000	857,000	1,655,000
Total deferred tax expense (benefit)	14,390,035	5,819,463	394,452
Income tax expense (benefit)	$ 64,159,167	47,588,528	35,181,517
Federal income tax statutory rate	35.00%
Reconciliation of the differences in income tax (benefit) expense [Abstract]
Income tax expense (benefit) at statutory rate	$ 66,984,000	50,084,000	36,978,000
State excise tax expense (benefit), net of federal tax effect	1,049,000	588,000	1,827,000
Tax-exempt securities	(2,510,000)	(2,543,000)	(2,675,000)
Federal tax credits	(282,000)	0	0
Bank owned life insurance	(1,242,000)	(892,000)	(849,000)
Insurance premiums	(159,000)	(306,000)	(401,000)
Changes in uncertain tax positions	0	0	392,000
Other items	319,000	658,000	(90,000)
Deferred tax valuation allowance	0	0	0
Income tax expense (benefit)	64,159,167	47,588,528	35,181,517
Deferred tax assets [Abstract]
Loan loss allowance	22,308,000	24,959,000
Loans	15,534,000	11,568,000
Insurance	869,000	823,000
Accrued liability for supplemental retirement agreements	5,587,000	2,476,000
Restricted stock and stock options	8,643,000	4,824,000
Deferred Tax Assets, Investments	4,275,000	0
Cash flow hedge	1,520,000	949,000
Net operating loss carryforward	0	0
Other real estate owned	149,000	587,000
Other deferred tax assets	7,897,000	2,905,000
Total deferred tax assets	66,782,000	49,091,000
Deferred tax liabilities [Abstract]
Depreciation and amortization	5,823,000	6,273,000
Core deposit intangible asset	5,621,000	3,786,000
Securities	0	2,337,000
Cash flow hedge	0	0
REIT dividends	4,602,000	1,772,000
FHLB related liabilities	285,000	1,385,000
Mortgage Servicing Rights	0	2,468,000
Other deferred tax liabilities	679,000	473,000
Total deferred tax liabilities	17,010,000	18,494,000
Net deferred tax assets	$ 49,772,000	30,597,000
Cumulative pre-tax loss position period	3 years
Unrecognized tax benefits, beginning of period	$ 134,000	391,000	0
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	694,000	(257,000)	0
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0	0	391,000
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	0	0	0
Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities	0	0	0
Unrecognized tax benefits, end of period	$ 828,000	$ 134,000	$ 391,000