Note 11. Employee Retirement Plans Employee Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Schedule of Costs of Retirement Plans [Table Text Block]

Components of Net Periodic Benefit Cost and Other Retirement Expenses

	Year Ended December 31,
	2023		2022		2021
	(in millions)
Defined contribution expense	$	10.1	$	9.1	$	8.6
Net periodic benefit cost – Supplemental Executive Retirement Plan (1)	$	0.7	$	0.7	$	0.7

(1) The non-service cost components of net periodic benefit cost are included in other, net (income) expense in our Consolidated Statements of Operations.