Earnings (Loss) Per Share

We calculate basic earnings (loss) per share by dividing our net earnings (loss) available to common shareholders by our weighted-average shares outstanding at the end of the period. The calculation for diluted earnings (loss) per share adjusts the weighted average shares outstanding for our dilutive unvested shares and stock units using the treasury stock method. Our calculations for basic and dilutive earnings (loss) per share for three and nine months ended September 30, 2019 and 2018 are as follows:



	Three Months					Nine Months
(dollars in millions, except per share data; shares and stock units in thousands)	2019			2018		2019			2018
Basic and dilutive net income (loss) available to common shareholders	$	(16.0	)	$	2.9	$	(88.7	)	$	2.7

Basic weighted average shares outstanding	33,259			33,051		33,098			32,827
Effect of dilutive securities:
Unvested shares and stock units^(a)	—			944		—			928
Dilutive weighted average shares outstanding	33,259			33,995		33,098			33,755

Basic earnings (loss) per share^(b)	$	(0.48	)	$	0.09	$	(2.68	)	$	0.08
Diluted earnings (loss) per share^(b)	$	(0.48	)	$	0.09	$	(2.68	)	$	0.08


(a)	Includes unvested shares of Common Stock, unvested stock units and vested stock units for which the underlying Common Stock has not been distributed.


(b)	Earnings (loss) per share is based on unrounded figures and not the rounded figures presented.

At September 30, 2019 and 2018, our anti-dilutive unvested shares, options, and stock units were approximately 319,000 and 54,000, respectively.