Earnings Per Share (Schedule of Earnings Per Share, Basic And Diluted) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerators [Abstract]
Numerator for both basic and diluted EPS, net income	$ 80,279,994	$ 77,183,441
Denominators [Abstract]
Denominator for basic EPS, weighted-average shares outstanding	289,210,621	295,031,431
Potentially dilutive shares resulting from stock plans	2,105,732	3,562,712
Denominator for diluted EPS	291,316,353	298,594,143
Shares related to stock plans not included in diluted average common shares outstanding because their effect would be anti-dilutive	7,866,330	1,184,635