Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Compensation Expense

Stock-based compensation cost by award type follows:

(in millions)	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Stock option awards	$	2.3	$	2.3	$	5.4	$	5.9
Restricted stock awards	1.7		1.7		5.0		3.9
Performance share awards	2.2		1.8		5.4		4.3
Stock appreciation rights	—		5.9		—		9.0
Total stock-based compensation cost incurred	6.2		11.7		15.8		23.1
Capitalized cost during the period	—		(5.9)		—		(9.3)
Amortization of capitalized cost during the period	—		8.8		—		14.3
Total stock-based compensation expense	$	6.2	$	14.6	$	15.8	$	28.1