Capital Stock - Schedule of Common Stock Outstanding (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 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