Capital Stock (Tables)

12 Months Ended

Dec. 31, 2015

Stockholders Equity Note [Abstract]

Schedule of Common Stock Outstanding

Common stock outstanding as of December 31, 2015, 2014 and 2013 was as follows:

(Number of shares in millions)	2015		2014		2013
Common stock:
Balance, beginning of year		104.8		104.0		102.4
Activity under stock plans		1.2		0.8		1.6
Balance, end of year		106.0		104.8		104.0
Treasury stock:
Balance, beginning of year		9.3		5.1		2.5
Repurchased		3.2		4.2		2.6
Balance, end of year		12.5		9.3		5.1
Common stock outstanding		93.5		95.5		98.9