Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2012

Earnings Per Share [Abstract]

Schedule Of Earnings Per Share Basic And Diluted

	Three Months Ended September 30,				Nine Months Ended September 30,
Numerators:	2012		2011		2012		2011
Numerator for both basic and diluted EPS, net income	$	41,877,083	$	43,397,064	$	128,988,206	$	124,202,115
Denominators:
Denominator for basic EPS, weighted-average shares outstanding		143,027,693		142,681,780		143,415,077		142,276,965
Potentially dilutive shares resulting from stock plans		556,682		1,633,240		1,002,142		1,859,434
Denominator for diluted EPS		143,584,375		144,315,020		144,417,219		144,136,399
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive		5,332,661		1,716,832		3,289,832		1,097,397