Earnings Per Share

12 Months Ended

Dec. 31, 2015

Earnings per Share

The denominator for basic and diluted earnings per share at December 31 is as follows:



	2015	2014	2013
Denominator for basic earnings per share—weighted-average shares	263.0	275.9	298.5
Effect of dilutive securities—employee stock options, non-vested restricted stock awards and convertible debentures	9.9	10.0	5.3
Denominator for diluted earnings per share	272.9	285.9	303.8

During the years ended December 31, 2015, 2014 and 2013, weighted-average shares related to certain stock options of 1.0, 0.5 and 4.2, respectively, were excluded from the denominator for diluted earnings per share because the stock options were anti-dilutive.

During the years ended December 31, 2015, 2014 and 2013, we issued approximately 0.4, 0.7 and 0.9 restricted stock units, respectively, of which vesting was contingent upon meeting certain earnings targets. Contingent restricted stock units are excluded from the denominator for diluted earnings per share and are included only if and when the contingency is met. The 2015 contingent restricted stock units are being measured over the three year period of 2015 through 2017, and remain contingent as of December 31, 2015. The 2014 and 2013 contingent restricted stock units were based on annual targets and were subsequently included in the denominator for diluted earnings per share for the years ended December 31, 2015 and 2014, respectively.

The Equity Units are potentially dilutive securities but were excluded from the denominator for diluted earnings per share for each of the years presented as the dilutive stock price threshold was not met.