Common Equity (Tables)

12 Months Ended

Dec. 31, 2022

Stockholders' Equity Note [Abstract]

Schedule of stock-based compensation expense and related tax benefit recognized in income

The following table summarizes our pre-tax stock-based compensation expense and the related tax benefit recognized in income for the years ended December 31:

(in millions)	2022		2021		2020
Stock options	$	6.5	$	6.5	$	6.0
Restricted stock	7.0		6.1		7.4
Performance units	21.3		3.1		22.3
Stock-based compensation expense	$	34.8	$	15.7	$	35.7
Related tax benefit	$	9.6	$	4.3	$	9.8

Schedule of stock option activity

The following is a summary of our stock option activity during 2022:

Stock Options	Number of Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in millions)
Outstanding as of January 1, 2022	3,111,907	$	69.84
Granted	437,269	$	96.04
Exercised	(622,459)	$	54.05
Forfeited	(16,778)	$	92.16
Outstanding as of December 31, 2022	2,909,939	$	77.03	6.2	$	49.7
Exercisable as of December 31, 2022	1,807,644	$	67.40	5.0	$	47.8

Schedule of restricted stock activity

The following restricted stock activity occurred during 2022:

Restricted Shares	Number of Shares	Weighted-Average Grant Date Fair Value
Outstanding and unvested as of January 1, 2022	99,061	$	88.89
Granted	72,211	$	96.04
Released	(76,109)	$	88.51
Forfeited	(5,278)	$	92.80
Outstanding and unvested as of December 31, 2022	89,885	$	94.73

Schedule of shares purchased to fulfill exercised stock options and restricted stock awards

The following is a summary of shares purchased to fulfill exercised stock options and restricted stock awards during the years ended December 31:

(in millions)	2022		2021		2020
Shares purchased	0.7		0.4		1.0
Cost of shares purchased	$	69.2	$	33.1	$	99.2

Schedule of common stock dividends declared

During the year ended December 31, 2022, our Board of Directors declared common stock dividends which are summarized below:

Date Declared	Date Payable	Per Share	Period
January 20, 2022	March 1, 2022	$0.7275	First quarter
April 21, 2022	June 1, 2022	$0.7275	Second quarter
July 21, 2022	September 1, 2022	$0.7275	Third quarter
October 20, 2022	December 1, 2022	$0.7275	Fourth quarter