Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Tax Disclosure [Abstract]

Schedule Of Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits

	2012		2011			2010
Beginning of year	$	2,476,000	$	2,483,000		$	2,411,000
Additions based on tax positions related to the current year	785,000		1,105,000			900,000
Additions for tax positions in prior years	907,000		208,000			76,000
Reductions for tax positions in prior years	—		(78,000		)	(35,000		)
Reductions as a result of completed audit examinations	—		(1,242,000		)	—
Reductions as a result of a lapse of the applicable statute of limitations	—		—			(869,000		)
End of year	$	4,168,000	$	2,476,000		$	2,483,000

Schedule Of Components Of Provision For Income Taxes

	2012		2011		2010
Currently payable:
Federal	$	76,507,760	$	63,307,583	$	54,032,045
State	2,450,000		1,663,000		789,000
Foreign	1,238,000		850,000		494,000
Total	80,195,760		65,820,583		55,315,045
Net deferred:
Primarily federal	843,000		13,943,000		10,391,000
Provision for income taxes	$	81,038,760	$	79,763,583	$	65,706,045

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

	2012		2011		2010
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net of federal income tax benefit	0.6		0.1		0.2
Domestic production exclusion	(2.9	)	(2.3	)	(2.5	)
Other	(0.2	)	(0.2	)	(0.4	)
Effective income tax rate	32.5	%	32.6	%	32.3	%

Schedule Of Deferred Income Tax Assets And Liabilities

	2012						2011
	Current			Non-Current			Current			Non-Current
Assets:
Accruals not currently deductible	$	3,721,183		$	186,997		$	2,465,349		$	152,716
Stock based compensation	12,044,953			1,696,966			8,730,729			1,473,236
Impairment loss on available-for-sale securities	—			327,308			—			471,401
Other	5,690,130			3,609			4,874,704			3,809
Total deferred income tax assets	21,456,266			2,214,880			16,070,782			2,101,162
Liabilities:
Excess tax over book depreciation	—			(47,704,521		)	—			(41,681,342		)
Patent costs	—			(8,137,111		)	—			(5,606,595		)
Unrealized gain on investments	—			(3,146,585		)	—			(3,027,206		)
Other	(527,417		)	—			(327,490		)	—
Net deferred income taxes	$	20,928,849		$	(56,773,337	)	$	15,743,292		$	(48,213,981	)