Earnings Per Share

The following table sets forth the computation of basic and diluted earnings (loss) per share (EPS):



	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018			2017
	(in thousands, except per share data)
Net income (loss) available to common shareholders	$	2,657	$	14,097	$	(143,009	)	$	29,942

Weighted average common shares outstanding - Basic	39,243		38,683		39,095			38,579
Dilutive effect of stock-based awards	546		649		—			695
Weighted average common shares outstanding - Diluted	39,789		39,332		39,095			39,274
Earnings (loss) per common share - Basic	$	0.07	$	0.36	$	(3.66	)	$	0.78
Earnings (loss) per common share - Diluted	$	0.07	$	0.36	$	(3.66	)	$	0.76

Stock-based Awards

For stock-based awards, the dilutive effect is calculated using the treasury stock method. Under this method, the dilutive effect is computed as if the awards were exercised at the beginning of the period (or at time of issuance, if later) and assumes the related proceeds were used to repurchase common stock at the average market price during the period. Related proceeds include the amount the employee must pay upon exercise and the future compensation cost associated with the stock award. Approximately 0.7 million and 1.1 million stock-based awards were excluded from the calculation of diluted EPS for the three and six months ended June 30, 2018, respectively, because they were anti-dilutive. Approximately 0.2 million stock-based awards were excluded from the calculation of diluted EPS for both the three and six months ended June 30, 2017 because they were anti-dilutive. These stock-based awards could be dilutive in future periods.