Earnings Per Share (Notes)

12 Months Ended

Dec. 31, 2018

Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]

Basic earnings per share are based on the weighted-average number of shares of common stock outstanding. Diluted earnings per share are based upon the weighted-average number of shares of common stock outstanding plus all potentially dilutive securities that were assumed to be converted into common shares at the beginning of the period under the treasury stock method. This method requires that the effect of potentially dilutive common stock equivalents (stock options, stock settled stock appreciation rights (SSARs), restricted stock or units, performance shares and warrants) be excluded from the calculation of diluted earnings per share for the periods in which losses from continuing operations are reported because the effect is anti-dilutive. The following table sets forth the computation of basic and diluted earnings per share:



	Year ended December 31,
Share amounts in millions	2018	2017	2016
Denominator for basic earnings per share:
Weighted average common shares outstanding	143.0	144.4	143.4
Effect of dilutive securities:
Dilutive effect of employee stock plans	1.4	2.0	1.7
Dilutive effect of stock warrants	—	—	0.2
Dilutive potential common shares	1.4	2.0	1.9
Denominator for diluted earnings per share:
Adjusted weighted average shares	144.4	146.4	145.3

For the year ended December 31, 2018, there were no SSARs that were considered not in-the-money for purposes of our earnings per share calculation.

For the years ended December 31, 2017 and 2016, SSARS relating to approximately 0.2 million and 2.6 million common shares were considered not in-the-money for purposes of our earnings per share calculation.