The Company calculates its basic income (loss) per share by dividing net income (loss) allocated to common shares outstanding by the weighted average number of common shares outstanding. Unvested shares of restricted stock participate in dividends on the same basis as common shares. As a result, these share-based awards meet the definition of participating securities and the Company applies the two-class method to compute earnings per share. The two-class method is an earnings allocation formula that treats participating securities as having rights to earnings that would otherwise have been available to common stockholders. In periods in which the Company has net losses, the losses are not allocated to participating securities because the participating security holders are not obligated to share in such losses.

The following table presents the number of participating securities and earnings allocated to those securities (in millions).

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
Earnings allocated to participating shareholders	$	—	$	—	$	—	$	—
Number of participating securities		1.1		0.9		1.1		1.0

The diluted earnings per share calculations include the effect of assumed exercise using the treasury stock method for unvested restricted stock units, except when the effect would be anti-dilutive. The following table presents the number of common shares used in the calculation of net income (loss) per share from continuing operations (in millions):

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
Weighted-average number of common shares-basic		25.5		25.1		25.4		25.1
Dilutive potential common shares		0.1		—		—		—
Weighted-average number of common shares-dilutive		25.6		25.1		25.4		25.1