Capital Stock (Tables)

12 Months Ended

Dec. 31, 2021

Stockholders' Equity Note [Abstract]

Schedule of Common Stock Outstanding

Common stock outstanding as of December 31, 2021, 2020 and 2019 was as follows:

(Number of shares in millions)	2021		2020		2019
Common stock:
Balance, beginning of year	109.7		109.3		108.5
Activity under stock plans		0.4		0.4		0.8
Balance, end of year	110.1		109.7		109.3
Treasury stock:
Balance, beginning of year	26.1		25.7		23.7
Repurchased		—		0.4		2.0
Balance, end of year	26.1		26.1		25.7
Common stock outstanding		84.0	83.6		83.6