Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Compensation Expense

Stock-based compensation cost by award type follows:

(in millions)	Three Months Ended March 31,
	2020		2019
Stock option awards	$	3.2	$	3.1
Restricted stock awards	2.1		2.0
Performance share awards	2.1		1.6
Restricted stock units	1.4		1.3
Stock appreciation rights	(3.6)		0.8
Total stock-based compensation cost incurred	5.2		8.8
Capitalized credit (cost) during the period	3.3		(1.2)
Amortization of capitalized cost during the period	4.2		0.6
Total stock-based compensation expense	$	12.7	$	8.2