Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

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:

	2018			2017			2016
Beginning of year	$	4,435,000		$	3,408,000		$	5,375,000
Additions based on tax positions related to the current year	1,677,000			941,000			756,000
Additions for tax positions in prior years	283,000			289,000			487,000
Reductions for tax positions in prior years	(163,000		)	(63,000		)	(2,949,000		)
Reductions as a result of completed audit examinations	(1,554,000		)	—			—
Reductions as a result of a lapse of the applicable statute of limitations	—			(140,000		)	(261,000		)
End of year	$	4,678,000		$	4,435,000		$	3,408,000

Schedule of Components of Provision For Income Taxes

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

	2018			2017			2016
Currently payable:
Federal	$	83,010,387		$	133,166,194		$	136,124,497
State	3,743,781			3,984,000			3,805,000
Foreign	1,776,837			2,440,000			540,000
Total	88,531,005			139,590,194			140,469,497
Deferred income tax (benefit) expense:
Primarily federal	(4,367,155		)	(14,585,412		)	22,500,000
Provision for income taxes	$	84,163,850		$	125,004,782		$	162,969,497

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:

	2018		2017		2016
Statutory federal income tax rate	21.0	%	35.0	%	35.0	%
State income taxes, net of federal income tax benefit	0.6		0.5		0.5
Domestic production exclusion	—		(2.8	)	(2.7	)
Research tax credit	(0.8	)	(0.8	)	(0.8	)
Increase (reduction) in reserve for uncertain tax provisions	0.1		0.1		(0.2	)
Change in tax rate on deferred taxes	0.5		(7.2	)	—
Foreign tax credit	(0.1	)	(0.8	)	—
Foreign derived intangible income deduction	(4.6	)	—		—
Stock compensation	(1.0	)	(1.0	)	—
Other	0.4		0.5		0.1
Effective income tax rate	16.1	%	23.5	%	31.9	%

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, 2018 and 2017, are as follows: 

	December 31,
	2018			2017
Assets:
Accruals not currently deductible	$	5,111,242		$	4,546,767
Stock based compensation	9,586,372			8,594,640
Other	356,039			3,679,680
Total deferred income tax assets	$	15,053,653		$	16,821,087
Liabilities:
Excess tax over book depreciation	(39,835,025		)	(46,123,681		)
Goodwill	(23,341,226		)	(18,972,334		)
Intangible assets	(5,089,042		)	(4,172,726		)
Other	(1,309,849		)	(6,440,990		)
Total deferred income tax liability	$	(69,575,142	)	$	(75,709,731	)
Net deferred income taxes	$	(54,521,489	)	$	(58,888,644	)