Common Shares

We calculate basic earnings per common share based upon the weighted average number of common shares outstanding. We calculate diluted earnings per share based upon the weighted average number of common shares outstanding plus the dilutive effect of common share equivalents calculated using the treasury stock method. The following is a summary of common shares and common share equivalents outstanding used in the calculations of basic and diluted earnings per share:



	Three Months Ended June 30,
	2012	2011
Denominator (shares in thousands):
Weighted average common shares outstanding—basic	57,911	59,255
Dilutive effect of common share equivalents	401	848
Weighted average common shares outstanding and common share equivalents—diluted	58,312	60,103

Options to purchase the following number of common shares were outstanding but excluded from the computation of diluted earnings per share because the combined exercise prices, unamortized fair values, and assumed tax benefits upon exercise were greater than the average market price for the common shares during the periods, so including these options would be anti-dilutive:

Three Months Ended June 30,

(shares in thousands)

Number of common share options