Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) - shares shares in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stockholders' Equity [Roll Forward]
Exercise of employee stock options (in shares)	0.1	0.0	0.6	0.3

Number of share options (or share units) exercised during the current period.

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