Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Restricted Stock Unit Activity

The following table summarizes information about vested and nonvested RSUs for 2021:

	RSUs
	Shares (in actual number of shares)	Weighted-Average Grant Date Fair Value
Nonvested at January 1	1,868,440	$	41.36
Granted	536,645	$	85.45
Vested	(671,926)	$	43.75
Forfeited	(76,713)	$	45.92
Nonvested at December 31	1,656,446	$	54.31

Weighted Average Grant-Date Fair Value of Restricted Stock Units Granted and Total Fair Value of Restricted Stock Units Vested

The weighted average grant-date fair value of RSUs and total fair value of RSUs vested are summarized in the following table:

	2021		2020		2019
Weighted average grant-date fair value of RSUs granted	$	85.45	$	44.28	$	35.51
Total fair value of RSUs vested (in millions)	$	51.8	$	23.2	$	9.0

Stock Option Activity

The following table summarizes stock option activity during 2021:

	Stock Options
	Shares (in actual number of shares)	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in millions)
Options outstanding at January 1	1,155,693	$	52.78
Granted	—	$	—
Exercised	(1,025,673)	$	53.13
Forfeited	—	$	—
Expired	—	$	—
Options outstanding and exercisable as of December 31	130,020	$	50.01	1.97	$	8.7
Options available for future grants at December 31	2,667,548

Total Stock-Based Compensation Expense

The following table summarizes the total stock-based compensation expense recognized in Selling, General, and Administrative Expenses in the Consolidated Statements of Income and the total recognized tax benefit related thereto:

	2021		2020		2019
RSUs	$	35.0	$	30.0	$	29.4
Stock options	—		0.1		0.9
Restricted stock	—		0.1		0.8
Total stock-based compensation expense	$	35.0	$	30.2	$	31.1
Tax benefit related to stock-based compensation expense	$	2.4	$	2.6	$	2.5