Earnings Per Share

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Earnings Per Share

The following table reconciles the numerators and denominators used in the calculation of basic and diluted earnings per share (EPS):

	Three months ended March 31,
	2013		2012
Numerators:
Numerator for both basic and diluted EPS, net income	$	45,430,567	$	46,344,584
Denominators:
Denominator for basic EPS, weighted-average shares outstanding	142,534,655		143,502,772
Potentially dilutive shares resulting from stock plans	540,810		1,485,229
Denominator for diluted EPS	143,075,465		144,988,001
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	5,034,165		2,233,907