Note 10. Employee Retirement Plans Net Retirement Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Service cost	$ 0.0	$ 0.1	$ 0.1
Interest	14.8	19.7	18.3
Expected return on plan assets	(20.9)	(23.0)	(27.4)
Amortization of actuarial loss	6.0	4.6	4.8
Amortization of prior service cost	(1.2)	0.0	0.0
Settlement loss	151.5	0.0	0.0
Other	0.0	0.0	0.6
Net periodic benefit cost	152.6	1.4	(3.6)
Profit sharing	9.0	11.0	11.1
Pension Cost (Reversal of Cost)	$ 161.6	$ 12.4	$ 7.5