Note 10. Employee Retirement Plans Employee Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2021

Retirement Benefits [Abstract]

Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]

Amounts recognized in other comprehensive income (loss)

	Year Ended December 31,
	2021		2020		2019
	(in millions)
Settlement of pension plan	$	—	$	151.5	$	—
Actuarial gain (loss)	0.4		10.4		(37.7)
Amortization of actuarial loss	0.3		6.0		4.6
Amortization of prior service cost	—		1.2		—
New prior service cost base	—		—		(1.5)
Total before income taxes	0.7		169.1		(34.6)
Income tax (benefit) expense	0.2		39.2		(7.9)
Net amount recognized in other comprehensive income (loss)	$	0.5	$	129.9	$	(26.7)

Defined Benefit Plan, Assumptions [Table Text Block]

Actuarial assumptions

	Year Ended December 31,
	2021	2020		2019
Assumptions used to determine benefit obligations at the annual measurement date were:
Obligation discount rate (1)	N/A	N/A		2.73	%
Assumptions used to determine net periodic benefit costs were:
Obligation discount rate (1)	N/A	2.71	%	4.45	%
Long-term rate of return on plan assets	N/A	3.90	%	4.90	%

Schedule of Costs of Retirement Plans [Table Text Block]

Components of Net Periodic Benefit Cost and Other Retirement Expenses

	Year Ended December 31,
	2021		2020		2019
	(in millions)
Expense Components
Service cost	$	—	$	—	$	0.1
Interest	0.4		14.8		19.7
Expected return on plan assets	—		(20.9)		(23.0)
Amortization of actuarial loss	0.3		6.0		4.6
Amortization of prior service cost	—		1.2		—
Settlement loss	—		151.5		—
Net periodic benefit cost	0.7		152.6		1.4
Defined contribution expense	8.6		7.5		9.6
Net expense	$	9.3	$	160.1	$	11.0

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]

Obligations and funded status

Information regarding the terminated Pension Plan and the SERP based upon a December 31 measurement date is as follows:

	Year Ended December 31,
	2021		2020
	(in millions)
Accumulated Benefit Obligations	$	14.5	$	15.5
Projected Benefit Obligations:
Beginning of year	$	15.5	$	557.9
Interest	0.4		14.8
Benefits paid	(1.0)		(23.0)
Actuarial (gain) loss	(0.4)		18.0
Settlements	—		(552.2)
End of year	$	14.5	$	15.5
Plans' Assets:
Beginning of year	$	23.6	$	548.5
Actual return on assets	—		49.3
Employer contributions	1.0		1.0
Benefits paid	(1.0)		(23.0)
Settlements	—		(552.2)
401(k) funding	(10.9)		—
Final annuity contract true-up, net of administrative expenses	3.9		—
Reversion of excess plan assets	(16.0)		—
End of year	$	0.6	$	23.6
Consolidated Balance Sheet Components:
Pension Plan:
Other assets	$	0.6	$	23.6
Accrued liabilities	—		—
Net funded status	$	0.6	$	23.6
SERP:
Other assets	$	—	$	—
Accrued liabilities	(14.5)		(15.5)
Net funded status	$	(14.5)	$	(15.5)