Employee Benefit Plans All Other Relevant Defined Benefit Pension and Other Postretirement Benefit Disclosures (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components			$ 1.7
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation			37.5
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components			1.5
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation			31.2
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months			55.5
Defined Benefit Plan, Expected Future Benefit Payments, Year Two			55.1
Defined Benefit Plan, Expected Future Benefit Payments, Year Three			55.5
Defined Benefit Plan, Expected Future Benefit Payments, Year Four			55.8
Defined Benefit Plan, Expected Future Benefit Payments, Year Five			56.5
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter			295.5
Lump Sum Distribution from Pension Trust				$ 104.2
Defined Benefit Plan, Settlements, Benefit Obligation				131.1
Defined Benefit Plan, Acceleration of Prior Service Cost due to remeasurement					$ 4.7
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Settlements, Benefit Obligation			0.0	131.1
Defined Benefit Plan, Recognized Net Gain Due to Settlements			0.0	35.5	0.0
Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Settlements, Benefit Obligation			0.0	0.0
Defined Benefit Plan, Recognized Net Gain Due to Settlements			0.0	$ 0.0	$ 0.0
UNITED KINGDOM | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and Other Postretirement Benefit Contributions			$ 18.3
Scenario, Forecast [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year		6.75%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2023
Scenario, Forecast [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Future Amortization of Gain (Loss)		$ 5.4
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)		0.1
Scenario, Forecast [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Future Amortization of Gain (Loss)		0.5
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)		2.7
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year		$ 16.0