10. Earnings Per Share

Basic earnings (loss) per share is computed as net earnings (loss) divided by the basic weighted average common shares outstanding of 140.5 million and 140.4 million shares for the three and nine months ended September 30, 2017, respectively, and 138.4 million and 137.4 million shares for the three and nine months ended September 30, 2016, respectively. The calculation of diluted earnings (loss) per share includes the effect of any dilutive equity incentive instruments. The Company uses the treasury stock method to calculate the effect of outstanding dilutive equity incentive instruments, which requires the Company to compute total proceeds as the sum of the amount the employee must pay upon exercise of the award and the amount of unearned stock-based compensation costs attributable to future services.

Equity incentive instruments for which the total employee proceeds from exercise exceed the average fair value of the same equity incentive instrument over the period have an anti-dilutive effect on earnings per share during periods with net earnings, and accordingly, the Company excludes them from the calculation. Anti-dilutive equity instruments of 0.3 million common shares were excluded from the computation of diluted net earnings per share for the three months ended September 30, 2017. Due to the net loss incurred during the nine months ended September 30, 2017 and the three and nine months ended September 30, 2016, the assumed exercise of all equity incentive instruments was anti-dilutive and, therefore, not included in the diluted loss per share calculation for those periods.

The following is a reconciliation of the average shares outstanding used to compute basic and diluted earnings per share:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Basic weighted average common shares outstanding		140,531,426		138,422,953		140,351,927		137,390,809
Effect of dilutive securities		2,805,751		—		—		—
Diluted weighted average common shares outstanding		143,337,177		138,422,953		140,351,927		137,390,809

No cash dividends were paid during any of the three and nine months ended September 30, 2017 and September 30, 2016.