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Earnings Per Share
12 Months Ended
Dec. 31, 2015
Earnings Per Share [Abstract]  
Earnings Per Share
Earnings Per Share
Diluted weighted average shares is calculated as basic weighted average shares plus the effect, calculated using the treasury stock method, of assuming that dilutive stock options have been exercised and that performance, restricted, and purchase share units have vested. All outstanding stock options, performance, restricted, and purchase share units had a dilutive effect for the years ended December 31, 2015, 2014 and 2013.