The Company computes earnings per share in accordance with ASC Topic 260, Earnings per Share ("ASC 260"), which requires earnings per share for each class of stock to be calculated using the two-class method. The two-class method is an allocation of income between the holders of common stock and the Company's participating security holders. Under the two-class method, income for the reporting period is allocated between common shareholders and other security holders based on their respective participation rights in undistributed income. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents are participating securities and, therefore, are included in computing earnings per share pursuant to the two-class method.

Basic net income per common share is computed by dividing net income allocated to common shareholders by the weighted-average number of shares of common stock outstanding for the period excluding unvested restricted stock units and performance units. Net income allocated to the holders of the Company's unvested restricted stock awards is calculated based on the shareholder’s proportionate share of weighted average shares of common stock outstanding on an if-converted basis.

For purposes of determining diluted net income per common share, basic net income per share is further adjusted to include the effect of potential dilutive common shares outstanding, including stock options, restricted stock units and performance units, and the impact of shares to be issued under the ESPP.

The following table is a reconciliation of net income and the shares used in calculating basic and diluted net income per common share for the three and nine months ended September 30, 2019 and 2018 (in thousands, except share and per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Numerator:
Net income	$	36,962		$	22,818		$	111,876		$	39,591
Adjustment for Basic EPS:
Earnings allocated to unvested shareholders		(260	)		(242	)		(922	)		(481	)
Adjusted net income	$	36,702		$	22,576		$	110,954		$	39,110
Denominator:
Weighted average common shares outstanding – Basic		46,980,439			46,869,998			46,947,109			46,841,036
Effect of dilutive shares:
Common stock equivalents arising from stock options and ESPP		249			754			1,142			1,682
Restricted stock awards and units and performance units		33,231			43,801			35,650			51,050
Weighted average common shares outstanding – Diluted		47,013,919			46,914,553			46,983,901			46,893,768
Net income per common share:
Basic	$	0.78		$	0.48		$	2.36		$	0.83
Diluted	$	0.78		$	0.48		$	2.36		$	0.83

For the three months ended September 30, 2019 and 2018, the combined effects of unvested restricted stock awards, restricted stock units, performance unit awards and stock options of none and 5,464, respectively, were excluded from the calculation of diluted EPS as their impact would have been antidilutive. For the nine months ended September 30, 2019 and 2018, the combined effects of unvested restricted stock awards, restricted stock units, performance unit awards and stock options of none and 4,143, respectively, were excluded from the calculation of diluted EPS as their impact would have been antidilutive. The impact of shares to be issued under the ESPP, which was not significant, was excluded from the calculation of diluted EPS as their impact would have been antidilutive.