Earnings (Loss) Per Share

We calculate basic earnings (loss) per share by dividing our net earnings (loss) by our weighted-average shares outstanding at the end of the period. The calculation for diluted earnings 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 the three and nine months ended September 30, 2017 and 2016 are as follows:



	Three Months				Nine Months
(dollars in millions, except per share data, shares and stock units in thousands)	2017		2016		2017			2016
Basic and dilutive net income (loss) available to common shareholders	$	3.0	$	13.9	$	(3.3	)	$	29.0

Basic weighted average shares outstanding	32,723		32,466		32,550			32,398
Effect of dilutive securities:
Unvested shares and stock units	869		728		—			517
Dilutive weighted average shares outstanding	33,592		33,194		32,550			32,915

Basic earnings (loss) per share^(a)	$	0.09	$	0.43	$	(0.10	)	$	0.89
Diluted earnings (loss) per share^(a)	$	0.09	$	0.42	$	(0.10	)	$	0.88


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

At September 30, 2017 and 2016, our anti-dilutive unvested shares, options, and stock units were approximately 80,000 and 213,000, respectively.