Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

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:

	2017			2016			2015
Beginning of year	$	3,408,000		$	5,375,000		$	8,288,000
Additions based on tax positions related to the current year	941,000			756,000			1,765,000
Additions for tax positions in prior years	289,000			487,000			428,000
Reductions for tax positions in prior years	(63,000		)	(2,949,000		)	(336,000		)
Reductions as a result of completed audit examinations	—			—			(4,162,000		)
Reductions as a result of a lapse of the applicable statute of limitations	(140,000		)	(261,000		)	(608,000		)
End of year	$	4,435,000		$	3,408,000		$	5,375,000

Schedule of Components of Provision For Income Taxes

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

	2017			2016		2015
Currently payable:
Federal	$	133,166,194		$	136,124,497	$	129,379,597
State	3,984,000			3,805,000		2,908,000
Foreign	2,440,000			540,000		276,000
Total	139,590,194			140,469,497		132,563,597
Deferred income tax (benefit) expense:
Primarily federal	(14,585,412		)	22,500,000		12,558,000
Provision for income taxes	$	125,004,782		$	162,969,497	$	145,121,597

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:

	2017		2016		2015
Statutory federal income tax rate	35.00	%	35.00	%	35.00	%
State income taxes, net of federal income tax benefit	0.50		0.50		0.40
Domestic production exclusion	(2.80	)	(2.70	)	(2.80	)
Research tax credit	(0.80	)	(0.80	)	(0.80	)
Increase (Reduction) in Reserve for Uncertain Tax Provisions	0.10		(0.20	)	(0.60	)
Change in Tax Rate on Deferred Taxes	(7.20	)	—		—
Foreign Tax Credit	(0.80	)	—		—
Other	(0.50	)	0.10		0.10
Effective income tax rate	23.50	%	31.90	%	31.30	%

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, 2017 and 2016, are as follows:

	December 31,
	2017			2016
Assets:
Accruals not currently deductible	$	4,546,767		$	4,282,470
Stock based compensation	8,594,640			18,701,361
Other	3,679,680			3,924,945
Total deferred income tax assets	16,821,087			26,908,776
Liabilities:
Excess tax over book depreciation	(46,123,681		)	(65,642,206		)
Goodwill	(18,972,334		)	(23,225,969		)
Unrealized gain on investments	(2,093,105		)	(1,435,322		)
Intangible assets	(4,172,726		)	(5,368,886		)
Other	(4,347,885		)	(2,449,012		)
Net deferred income taxes	$	(58,888,644	)	$	(71,212,619	)

Net current and non-current tax assets and liabilities are included in the consolidated balance sheets as follows:

	December 31,
	2017			2016
Long-term assets	16,821,087			26,908,776
Long-term liabilities	(75,709,731		)	(98,121,395		)
Total deferred tax liability	$	(58,888,644	)	$	(71,212,619	)