Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Components of Provision For Income Taxes

The components of the provision for income taxes are as follows:

	2019			2018			2017
Currently payable:
Federal	$	73,563,685		$	83,010,387		$	133,166,194
State	3,765,929			3,743,781			3,984,000
Foreign	1,468,018			1,776,837			2,440,000
Total	78,797,632			88,531,005			139,590,194
Deferred income tax (benefit) expense:
Primarily federal	(3,066,237		)	(4,367,155		)	(14,585,412		)
Provision for income taxes	$	75,731,395		$	84,163,850		$	125,004,782

Schedule of Effective Income Tax Rates Different From Statutory Federal Income Tax Rates

The effective income tax rates are different from the statutory federal income tax rates for the following reasons:

	2019		2018		2017
Statutory federal income tax rate	21.0	%	21.0	%	35.0	%
State income taxes, net of federal income tax benefit	0.6		0.6		0.5
Domestic production exclusion	—		—		(2.8	)
Research tax credit	(1.1	)	(0.8	)	(0.8	)
Increase in reserve for uncertain tax provisions	0.3		0.1		0.1
Change in tax rate on deferred taxes	—		0.5		(7.2	)
Foreign tax credit	(0.1	)	(0.1	)	(0.8	)
Foreign derived intangible income deduction	(4.8	)	(4.6	)	—
Stock compensation	(1.1	)	(1.0	)	(1.0	)
Other	0.3		0.4		0.5
Effective income tax rate	15.1	%	16.1	%	23.5	%

Schedule of Deferred Income Tax Assets And Liabilities

The tax effect of temporary differences which give rise to deferred income tax assets and liabilities at    December 31, 2019 and 2018, are as follows: 

	December 31,
	2019			2018
Assets:
Accruals not currently deductible	$	6,478,146		$	5,111,242
Stock based compensation	9,100,745			9,586,372
Other	66,830			356,039
Total deferred income tax assets	$	15,645,721		$	15,053,653
Liabilities:
Excess tax over book depreciation	(30,725,471		)	(39,835,025		)
Goodwill	(27,799,640		)	(23,341,226		)
Intangible assets	(6,171,628		)	(5,089,042		)
Other	(2,403,131		)	(1,309,849		)
Total deferred income tax liability	$	(67,099,870	)	$	(69,575,142	)
Net deferred income taxes	$	(51,454,149	)	$	(54,521,489	)

Schedule of Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

	2019			2018			2017
Beginning of year	$	4,678,000		$	4,435,000		$	3,408,000
Additions based on tax positions related to the current year	1,695,000			1,677,000			941,000
Additions for tax positions in prior years	657,000			283,000			289,000
Reductions for tax positions in prior years	(38,000		)	(163,000		)	(63,000		)
Reductions as a result of completed audit examinations	—			(1,554,000		)	—
Reductions as a result of a lapse of the applicable statute of limitations	(600,000		)	—			(140,000		)
End of year	$	6,392,000		$	4,678,000		$	4,435,000