Retirement and Employee Benefit Plans (Amounts Recognized in Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Total change in value of pension and postretirement liabilities	$ (9.0)	$ 31.0	$ 13.0
Other postretirement benefit, tax effects	1.0
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain arising during the year	0.0	30.0
Amortization of prior service cost	0.0	(2.0)
Tax valuation allowance release impact on pension settlements	(14.0)	0.0
Settlements	(2.0)	(1.0)
Less: Tax effect (1)	0.0	0.0
Total change in value of pension and postretirement liabilities	(16.0)	27.0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain arising during the year	7.0	4.0
Amortization of prior service cost	0.0	0.0
Tax valuation allowance release impact on pension settlements	0.0	0.0
Settlements	0.0	0.0
Less: Tax effect (1)	0.0	0.0
Total change in value of pension and postretirement liabilities	$ 7.0	$ 4.0