Earnings Per Common Share

Basic and diluted earnings per common share are computed by dividing net income by the weighted-average number of basic and diluted common shares outstanding, respectively. The weighted-average number of diluted common shares includes the impact of dilutive securities, including outstanding stock options and unvested restricted stock and restricted stock units. The table below reconciles the weighted-average basic and diluted common shares outstanding:



	Three Months Ended June 30,		Six Months Ended June 30,
	2017	2016	2017	2016
	(in thousands)
Weighted average number of common shares outstanding - basic	73,276	72,568	73,176	72,466
Effect of dilutive securities⁽¹⁾	993	748	932	699
Weighted average number of common shares outstanding - diluted	74,269	73,316	74,108	73,165

⁽¹⁾

Certain outstanding stock option awards are anti-dilutive and were therefore excluded from the calculation of the weighted average number of diluted common shares outstanding. During the three and six months ended June 30, 2017, options to purchase 0.5 million shares having a weighted average exercise price of $39.38 per share were excluded. During the three and six months ended June 30, 2016, options to purchase 0.6 million shares having a weighted average exercise price of $34.14 per share were excluded.