Earnings per Share (Notes)

12 Months Ended

Dec. 31, 2014

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Earnings Per Share

The numerator for both basic and diluted earnings per share is net income. The denominator for basic earnings per share is the weighted-average number of common shares outstanding during the period. The 2013 denominator was impacted by the common shares issued during both the IPO and the underwriters' exercise in full of the overallotment option granted to them in connection with the IPO. Because such common shares were issued on July 2, 2013 and July 31, 2013, respectively, they are only partially reflected in the 2013 denominator. Such shares are fully reflected in the 2014 denominator. See Note 9 for additional discussion of the IPO.

The dilutive effect of outstanding restricted stock, restricted stock units, stock options, Coworker Stock Purchase Plan units and MPK Plan units is reflected in the denominator for diluted earnings per share using the treasury stock method.

The following is a reconciliation of basic shares to diluted shares:

	Years Ended December 31,
(in millions)	2014	2013	2012
Weighted-average shares - basic	170.6	156.6	145.1
Effect of dilutive securities	2.2	2.1	0.7
Weighted-average shares - diluted	172.8	158.7	145.8

There was an insignificant amount of potential common shares excluded from diluted earnings per share for the years ended December 31, 2014, 2013 and 2012, as their inclusion would have had an anti-dilutive effect.